JP5331309B2 - Photoelectric conversion device and solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element optimum for a solid-state imag sensor which can pick up infrared images, based on infrared light reflected from a phtographic subject. <P>SOLUTION: The photoelectric conversion element is equipped with a pair of electrodes, and a photoelectric conversion portion containing a photoelectric conversion film provided between the pair of electrodes. The photoelectric conversion film is constituted by containing an organic photoelectric conversion material. The organic photoelectric conversion material contains a compound, represented by the general formula (SQ-1), wherein A and B are independently a substituent whose bonding position is sp<SP>2</SP>carbon. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and an infrared organic photoelectric conversion film provided between the pair of electrodes.

  Conventional visible light sensors are generally formed by forming a photoelectric conversion element by forming a PN junction in a semiconductor such as Si, and as a solid-state imaging element, a photoelectric conversion element is formed in a semiconductor. 2. Description of the Related Art Planar light receiving elements that are two-dimensionally arranged and read out signals generated by photoelectric conversion in each photoelectric conversion element in a CCD or CMOS format are widely used. As a method for realizing a color solid-state imaging device, a structure in which a color filter that transmits only light of a specific wavelength for color separation is generally provided on the light incident surface side of the planar light receiving device, in particular, Currently, a single-plate sensor that regularly arranges color filters that transmit blue light, green light, and red light on each two-dimensionally arranged photoelectric conversion element is often used as a method widely used in digital cameras and the like. Are known.

  In addition, as a sensor that senses infrared light, a thermal type sensor (thermoelectromotive force type, pyroelectric effect, thermocouple effect, etc.) or a quantum type sensor (photovoltaic effect, photoconductive effect, photoelectron emission effect) is used. Is common. Most of these are composed of inorganic semiconductors, and inorganic semiconductors have the property of broadly absorbing short waves from a certain wavelength, so they absorb light in the entire region from infrared to visible light. It has the characteristic to end.

  When trying to obtain images of visible light and infrared light at the same time, the incident light is separated into infrared light and visible light and detected by separate devices, or visible light and infrared light are detected on one device. A method of arranging two-dimensionally transmissive color filters can be considered. In this case, it is possible to obtain an image by visible light and infrared light at the same time, but the device and the apparatus become large and the cost is increased. The processing is difficult, and since the color filter transmits only light of a limited wavelength, the light that has not been transmitted is not used and the light utilization efficiency is poor.

  In order to solve these drawbacks, a method of stacking photoelectric conversion units that can detect different light wavelengths can be considered. As such a system, when limited to visible light, for example, a layered structure is formed vertically in a silicon substrate by utilizing the fact that the absorption coefficient of Si has wavelength dependence, and each depth is A sensor that separates colors according to a difference is disclosed in Patent Document 1, and a sensor having a structure in which an organic photoelectric conversion film is stacked above a silicon substrate is disclosed in Patent Document 2.

  In a method in which a photoelectric conversion unit that detects infrared light and a photoelectric conversion unit that detects visible light are stacked in the vertical direction, when Si is used, photoelectric conversion that further detects infrared light with respect to the sensor described in Patent Document 1. It is necessary to place the part on the bottom layer of the silicon substrate, but originally, in the depth direction of the silicon substrate, the absorption range overlaps in each part and the spectral characteristics are poor, so there is a disadvantage that color separation is inferior Since the upper layer absorbs infrared light, the infrared light reaching the lowermost layer in the silicon substrate is reduced, resulting in a drawback that sensitivity is lowered.

As described above, when an inorganic semiconductor is used, it is difficult to absorb only infrared light by itself. However, since an organic film can be designed to absorb only a specific wavelength region, only infrared light is used. It can be used as a layer that absorbs.
The organic film can be formed by spin coating or other methods, or by evaporation under vacuum to evaporate the material and deposit it on the substrate. It is desirable to use a vapor deposition method in order to be able to perform the multilayering with more flexibility. In that case, croconium and merocyanine dyes, which are representative dyes that absorb in the infrared, have a low decomposition temperature and are easily decomposed by heating during vapor deposition, making it difficult to form a film. . A phthalocyanine dye is reported in Patent Document 3 as a known material that has absorption in the infrared region, can be deposited, and exhibits high photoelectric conversion performance in electrophotography, organic thin film solar cells, and the like. However, as a result of investigations by the inventors, when a phthalocyanine-based material is used, when a voltage is applied in order to obtain high photoelectric conversion performance, in general, a dark current that causes noise in an imaging device is used. There is a tendency that (dark current) tends to increase, and it is difficult to obtain high S / N.
In addition to the above, squarylium dye is known in Non-Patent Document 1 as a material that can be deposited and exhibits significant photoelectric conversion performance. In general, squarylium-based dyes are often easily decomposed during vapor deposition, and Non-Patent Document 2 reports a structure that improves the vapor deposition properties by increasing the decomposition temperature and lowering the vapor deposition temperature. In the above-mentioned document 2, the compound 5 described later is disclosed. By adding a bulky and difficult-to-decompose substituent, it is easy to deposit by suppressing intermolecular interaction, and by suppressing decomposition, it is deposited. Improves sex. However, as a result of the inventors examining the photoelectric conversion performance of these materials, the photoelectric conversion performance was remarkably low. As described above, when the deposition property is improved by providing a substituent that causes steric hindrance, the intermolecular interaction is low, so that the signal charge transportability tends to be low.
US Pat. No. 5,965,875 JP 2003-332551 A JP-A-63-186251 Applid Physics Letters, 29,414 (1975) J. Phys. Chem. B, 106, 4370 (2002)

  The present invention has been made in view of the above circumstances, and provides a squarylium dye having excellent vapor deposition properties, which is used in a photoelectric conversion element suitable for photographing an infrared image based on infrared light, and the squarylium. To provide a photoelectric conversion element that is optimal for a solid-state imaging device capable of simultaneously capturing a visible image based on visible light reflected from a subject and capturing an infrared image based on infrared light using a system dye. Objective.

  The photoelectric conversion element of the present invention is a photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, and the photoelectric conversion film has excellent vapor deposition properties. Contains squarylium pigments. The photoelectric conversion film further includes an organic photoelectric conversion material that has an absorption peak of an absorption spectrum in a range including a visible region and an infrared region in the infrared region, and generates an electric charge according to the absorbed light. The photoelectric conversion material contains a squarylium dye. Specifically, the present invention has been achieved by the following means.

（式中、Ｒ^１〜Ｒ^８は、それぞれ独立に水素原子または置換基を表す。複数のＲ^１〜Ｒ^８は連結して環を形成してもよい。Ｂは、キノリン核、ピリリウム核、チオピリリウム核、アズレン核またはジヒドロペリミジン核が結合した無置換メチン基を表し、該メチン基は該キノリン核、ピリリウム核、チオピリリウム核、アズレン核またはジヒドロペリミジン核の炭素原子と結合している。）
＜２＞
前記一般式（ＳＱ−２）が下記の一般式（ＳＱ−３）で表されることを特徴とする＜１＞に記載の光電変換素子。
一般式（ＳＱ−３）

（式中、Ｂは一般式（ＳＱ−２）と同義である。）
＜３＞
一対の電極と、前記一対の電極間に設けられた光電変換膜とを含む光電変換部を備える光電変換素子であって、前記光電変換膜が、可視域と赤外域を併せた範囲における吸収スペクトルの吸収極大を赤外域に持ち、吸収した光に応じた電荷を発生する有機光電変換材料を含んで構成され、該有機光電変換材料の少なくとも１つが＜１＞又は＜２＞に記載の一般式（ＳＱ−２）または（ＳＱ−３）で示される化合物であり、
前記一対の電極がＴＣＯを含んでなることを特徴とする＜１＞又は＜２＞に記載の光電変換素子。
＜４＞
前記ＴＣＯがＩＴＯであることを特徴とする＜３＞に記載の光電変換素子。
＜５＞
前記光電変換部が上方に積層された半導体基板を備え、
可視域と赤外域を併せた範囲における吸収スペクトルの吸収極大を可視域に持ち、吸収した光に応じた電荷を発生する可視光光電変換部を前記半導体基板と前記光電変換部の間に少なくとも１つ備えることを特徴とする＜３＞又は＜４＞に記載の光電変換素子。
＜６＞
前記半導体基板が、前記光電変換部及び前記可視光光電変換部の各々で発生した電荷を蓄積する蓄積部と、前記蓄積部に蓄積された電荷に応じた信号を読み出す信号読み出し部とを備えることを特徴とする＜５＞に記載の光電変換素子。
＜７＞
前記光電変換部が上方に積層された半導体基板を備え、
可視域と赤外域を併せた範囲における吸収スペクトルの吸収ピークを可視域に持ち、吸収した光に応じた電荷を発生する可視光光電変換部を前記半導体基板内に少なくとも１つ備えることを特徴とする＜３＞〜＜６＞のいずれか一項に記載の光電変換素子。
＜８＞
前記半導体基板が、前記光電変換部で発生した電荷を蓄積する蓄積部と、前記蓄積部に蓄積された電荷に応じた信号を読み出す信号読み出し部とを備えることを特徴とする＜７＞に記載の光電変換素子。
＜９＞
前記可視光光電変換部を複数備え、
前記複数の可視光光電変換部が、それぞれ異なる波長に吸収ピークを持つことを特徴とする＜５＞〜＜８＞のいずれか一項に記載の光電変換素子。
＜１０＞
前記複数の可視光光電変換部が、前記光電変換部への光入射方向に積層されていることを特徴とする＜９＞に記載の光電変換素子。
＜１１＞
前記可視光光電変換部を複数備え、
前記複数の可視光光電変換部が、それぞれ異なる波長に吸収ピークを持ち、且つ、前記光電変換部への光入射方向に対して垂直方向に配列されていることを特徴とする＜８＞に記載の光電変換素子。
＜１２＞
前記可視光光電変換部を３つ備え、
前記３つの可視光光電変換部が、赤色の波長域の光を吸収するＲ光電変換部と、緑色の波長域の光を吸収するＧ光電変換部と、青色の波長域の光を吸収するＢ光電変換部であることを特徴とする＜１０＞又は＜１１＞に記載の光電変換素子。
＜１３＞
前記光電変換部を透過した光が前記可視光光電変換部に入射するように、前記光電変換部と前記可視光光電変換部が平面視において重なっていることを特徴とする＜１＞〜＜１２＞のいずれか一項に記載の光電変換素子。
＜１４＞
前記光電変換膜が、正孔ブロッキング層、および電子ブロッキング層を含んでなることを特徴とする＜１＞〜＜１３＞のいずれか一項に記載の光電変換素子。
＜１５＞
少なくとも一方の光電変換部が同一平面上にアレイ状に配置された＜１＞〜＜１４＞のいずれか一項に記載の光電変換素子を備えることを特徴とする固体撮像素子。
なお、本発明は上記＜１＞〜＜１５＞に関するものであるが、以下、その他の事項についても参考のために記載した。
（１）一対の電極と、前記一対の電極間に設けられた光電変換膜とを含む光電変換部を備える光電変換素子であって、前記光電変換膜が、有機光電変換材料を含んで構成され、該有機光電変換材料が下記の一般式（ＳＱ−１）で示される化合物を含むことを特徴とする光電変換素子。
一般式（ＳＱ−１） <1>
A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film includes an organic photoelectric conversion material, A photoelectric conversion element, wherein the photoelectric conversion material contains a compound represented by the following general formula (SQ-2).
General formula (SQ-2)

(Wherein R ^{1 to} R ⁸ each independently represents a hydrogen atom or a substituent. A plurality of R ^{1 to} R ⁸ may be linked to form a ring. B represents a quinoline nucleus, a pyrylium nucleus, It represents an unsubstituted methine group to which a thiopyrylium nucleus, an azulene nucleus or a dihydroperimidine nucleus is bonded, and the methine group is bonded to a carbon atom of the quinoline nucleus, pyrylium nucleus, thiopyrylium nucleus, azulene nucleus or dihydroperimidine nucleus . )
<2>
Said general formula (SQ-2) is represented by the following general formula (SQ-3), The photoelectric conversion element as described in <1> characterized by the above-mentioned.
General formula (SQ-3)

(In the formula, B has the same meaning as the general formula (SQ-2).)
< 3 >
A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film has an absorption spectrum in a range in which a visible region and an infrared region are combined. And an organic photoelectric conversion material that generates an electric charge according to the absorbed light, and at least one of the organic photoelectric conversion materials is represented by the general formula according to <1> or <2> A compound represented by (SQ-2) or (SQ-3),
The photoelectric conversion element according to <1> or <2> , wherein the pair of electrodes includes TCO.
< 4 >
Said TCO is ITO, The photoelectric conversion element as described in < 3 > characterized by the above-mentioned.
< 5 >
The photoelectric conversion part comprises a semiconductor substrate laminated above,
A visible light photoelectric conversion unit that has an absorption maximum of an absorption spectrum in a range including a visible region and an infrared region in the visible region and generates a charge according to absorbed light is at least 1 between the semiconductor substrate and the photoelectric conversion unit. The photoelectric conversion element as described in <3> or <4> characterized by comprising.
< 6 >
The semiconductor substrate includes an accumulation unit that accumulates charges generated in each of the photoelectric conversion unit and the visible light photoelectric conversion unit, and a signal reading unit that reads a signal corresponding to the charge accumulated in the accumulation unit. < 5 > characterized by these. The photoelectric conversion element as described in < 5 >.
< 7 >
The photoelectric conversion part comprises a semiconductor substrate laminated above,
The semiconductor substrate has at least one visible light photoelectric conversion portion that has an absorption peak of an absorption spectrum in a visible region and an infrared region in the visible region and generates a charge corresponding to the absorbed light. The photoelectric conversion element according to any one of <3> to <6> .
< 8 >
< 7 >, wherein the semiconductor substrate includes an accumulation unit that accumulates charges generated in the photoelectric conversion unit, and a signal readout unit that reads a signal corresponding to the charges accumulated in the accumulation unit. Photoelectric conversion element.
< 9 >
A plurality of the visible light photoelectric conversion units,
The photoelectric conversion element according to any one of <5> to <8> , wherein the plurality of visible light photoelectric conversion units have absorption peaks at different wavelengths.
< 10 >
The photoelectric conversion element according to < 9 >, wherein the plurality of visible light photoelectric conversion units are stacked in a light incident direction to the photoelectric conversion unit.
< 11 >
A plurality of the visible light photoelectric conversion units,
< 8 >, wherein the plurality of visible light photoelectric conversion units have absorption peaks at different wavelengths, respectively, and are arranged in a direction perpendicular to a light incident direction to the photoelectric conversion unit. Photoelectric conversion element.
< 12 >
Three visible light photoelectric conversion units are provided,
The three visible light photoelectric conversion units absorb an R photoelectric conversion unit that absorbs light in the red wavelength range, a G photoelectric conversion unit that absorbs light in the green wavelength range, and B that absorbs light in the blue wavelength range. The photoelectric conversion element according to <10> or <11> , which is a photoelectric conversion unit.
< 13 >
<1> to < 12 , wherein the photoelectric conversion unit and the visible light photoelectric conversion unit overlap each other in plan view so that light transmitted through the photoelectric conversion unit is incident on the visible light photoelectric conversion unit. > The photoelectric conversion element as described in any one of.
< 14 >
The photoelectric conversion element according to any one of <1> to < 13 >, wherein the photoelectric conversion film includes a hole blocking layer and an electron blocking layer.
< 15 >
A solid-state imaging device comprising the photoelectric conversion device according to any one of <1> to < 14 >, wherein at least one photoelectric conversion unit is arranged in an array on the same plane .
In addition, although this invention is related to said <1>-< 15 >, below, other matters were also described for reference.
(1) A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film includes an organic photoelectric conversion material. The organic photoelectric conversion material contains a compound represented by the following general formula (SQ-1).
General formula (SQ-1)

(In the formula, A and B each independently represent a substituent whose bonding position is sp ² carbon.)
(2) The photoelectric conversion element according to (1), wherein the general formula (SQ-1) is represented by the following general formula (SQ-2).
General formula (SQ-2)

(In the formula, R ^{1 to} R ⁸ each independently represents a hydrogen atom or a substituent. A plurality of R ^{1 to} R ⁸ may be linked to form a ring. B in the general formula (SQ-1) Is synonymous with.)
(3) The photoelectric conversion element according to (1) or (2), wherein the general formula (SQ-2) is represented by the following general formula (SQ-3).
General formula (SQ-3)

(In the formula, B has the same meaning as in the general formula (SQ-2).)
(4) The photoelectric according to any one of claims 1 to 3, wherein the B is represented by the same structure as the A and the portion corresponding to the A, and the decomposition temperature of the compound is 200 ° C or higher. Conversion element.
(5) A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film combines a visible region and an infrared region. An organic photoelectric conversion material having an absorption maximum in the infrared region in the infrared region and generating an electric charge according to the absorbed light is formed, and at least one of the organic photoelectric conversion materials is any one of claims 1 to 4 A photoelectric conversion element, wherein the photoelectric conversion unit transmits 50% or more of light in a visible range of 400 to 600 nm as a whole, wherein the photoelectric conversion unit is a compound represented by the general formula (SQ-1).
(6) The absorption maximum wavelength of the photoelectric conversion film containing the compound represented by the general formula (SQ-1) is 650 nm or more (preferably 700 nm or more), and the photoelectric conversion unit is visible light as a whole. The photoelectric conversion element according to (5), wherein 75% or more is transmitted.
(7) The photoelectric conversion element according to (5) or (6), wherein the photoelectric conversion film has an absorption rate at an absorption maximum wavelength of 50% or more.

(8) The visible light and infrared light transmittance of the light incident side electrode of the pair of electrodes is 95% or more, and any one of (5) to (7) Photoelectric conversion element.
(9) The transmittance of light in the visible region of the electrode on the opposite side to the light incident side of the pair of electrodes is 95% or more, wherein any one of (5) to (8) Photoelectric conversion element.
(10) The photoelectric conversion element according to any one of (5) to (9), wherein the pair of electrodes is TCO.

(11) The photoelectric conversion element according to any one of (5) to (10), wherein the TCO is ITO.
(12) The photoelectric conversion unit includes a semiconductor substrate stacked above, has an absorption maximum of an absorption spectrum in a range including a visible region and an infrared region in the visible region, and generates a charge corresponding to the absorbed light. The photoelectric conversion element according to claim 5, wherein at least one visible light photoelectric conversion unit is provided between the semiconductor substrate and the photoelectric conversion unit.
(13) An accumulation unit that accumulates charges generated in each of the photoelectric conversion unit and the visible light photoelectric conversion unit, and a signal reading unit that reads out a signal corresponding to the charges accumulated in the accumulation unit. The photoelectric conversion element according to (12), comprising:

(14) The photoelectric conversion unit includes a semiconductor substrate stacked above, has an absorption peak of an absorption spectrum in a range including a visible region and an infrared region in the visible region, and generates a charge corresponding to the absorbed light. At least one visible light photoelectric conversion part is provided in the semiconductor substrate, The photoelectric conversion element according to any one of (5) to (13),
(15) The semiconductor substrate includes an accumulation unit that accumulates charges generated in the photoelectric conversion unit, and a signal readout unit that reads out a signal corresponding to the charges accumulated in the accumulation unit. The photoelectric conversion element as described in 14).
(16) A plurality of the visible light photoelectric conversion units are provided, and the plurality of visible light photoelectric conversion units have absorption peaks at different wavelengths, respectively, according to any one of (12) to (15) Photoelectric conversion element.

(17) The photoelectric conversion element according to (16), wherein the plurality of visible light photoelectric conversion units are stacked in a light incident direction to the photoelectric conversion unit.
(18) The device includes a plurality of visible light photoelectric conversion units, the plurality of visible light photoelectric conversion units each having an absorption peak at a different wavelength, and in a direction perpendicular to a light incident direction to the photoelectric conversion unit. The photoelectric conversion element according to (15), which is arranged.

(19) Three visible light photoelectric conversion units are provided, and the three visible light photoelectric conversion units absorb an R photoelectric conversion unit that absorbs light in a red wavelength region, and G absorbs light in a green wavelength region. The photoelectric conversion device according to (17) or (18), wherein the photoelectric conversion unit is a photoelectric conversion unit and a B photoelectric conversion unit that absorbs light in a blue wavelength range.
(20) The photoelectric conversion unit and the visible light photoelectric conversion unit overlap each other in plan view so that light transmitted through the photoelectric conversion unit is incident on the visible light photoelectric conversion unit (1). )-(19) The photoelectric conversion element in any one of.

(21) The photoelectric conversion element according to any one of (1) to (20), wherein the photoelectric conversion film comprises a hole blocking layer and an electron blocking layer.

(22) A solid-state imaging device comprising the photoelectric conversion device according to any one of (1) to (21), wherein at least one photoelectric conversion unit is arranged in an array on the same plane.

(23) In the general formula (SQ-3) described in (3), B comprises any one of a quinoline nucleus, a pyrylium nucleus, a thiopyrylium nucleus, an azulene nucleus, and a dihydroperimidine nucleus. A squarylium compound.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the photoelectric conversion element which shows high photoelectric conversion efficiency, is low noise, has good vapor deposition property, and contains a squarylium type pigment | dye, and imaging | photography of the visible image based on the visible light reflected from the structure subject And a photoelectric conversion element optimal for a solid-state imaging device capable of simultaneously taking an infrared image based on infrared light.

The squarylium compound (squarylium dye) used in the present invention will be described. These dyes are useful as the organic photoelectric conversion material, and a squarylium dye suitable for the vapor deposition method will be described in detail.
The squarylium dye is an organic substance that can absorb long-wave light with a simpler structure due to the structure of the substituent, and should be a material that makes it easy to obtain a low-noise photoelectric conversion element in the study of the inventors. There was found. Therefore, it is considered that a photoelectric conversion element having a high visible light transmission property having a high S / N sensitivity in the infrared region can be realized by improving the vapor deposition property and appropriately constructing a laminated structure of photoelectric conversion films.
In the vapor deposition method, a temperature distribution is generated in the material disposed in the vapor deposition source during the vapor deposition depending on the shape of the vapor deposition source, the way of raising the temperature, and the like. If the temperature distribution is within the range of the maximum temperature T1 and the minimum temperature T2, the decomposition temperature Tdecom, the temperature required for vapor deposition (material vaporization) (= vapor deposition temperature) Tdepo, decomposition occurs in a temperature range higher than Tdecom. Similarly, since the material is vaporized in a temperature range higher than Tdepo, if Tdecom>T2>T1> Tdepo, decomposition does not occur and only vapor deposition is possible. At this time, if the difference between the deposition temperature and the decomposition temperature is small and T2>Tdecom>T1> Tdepo, or T2>T1>Tdecom> Tdepo, decomposition occurs in a temperature range larger than the decomposition temperature, The material is being decomposed along with the vapor deposition. When the decomposition temperature is low and the vapor deposition temperature or lower, decomposition occurs before vaporization of the material.

Therefore, in order to improve the vapor deposition properties (= vapor deposition without decomposition as much as possible)
A. Increase the difference between the decomposition temperature and the deposition temperature (ΔTd) = Tdecom-Tdepo (> 0).
(The width of ΔTd is made larger than the temperature range of the vapor deposition material.)
B. Make the temperature distribution in the material to be deposited uniform (decrease T2-T1).
(The temperature range of the vapor deposition material should be within the range of ΔTd.)
It is desirable to improve at least one of the above, and preferably both.

  Measures related to A are “increasing the decomposition temperature” and “decreasing the deposition temperature”. As a measure for increasing the decomposition temperature, it is important to select a substituent that is difficult to decompose in the squarylium compound. In the sense of strengthening the bond between the substituent and the central squaric acid structure (referred to herein as the “2-cyclobutene-1,3-dione nucleus”), the central squaric acid structure (2-cyclobutene-1 , 3-dione nucleus) can be contrived such as providing a group that forms a hydrogen bond with the oxygen atom in the substituent. In addition, the decomposability within the substituent is considered to be preferably a condensed ring structure. When a long alkyl group or the like is added, it tends to be easily decomposed. About the ease of decomposition | disassembly of each substituent, when both ends of general formula (SQ-1) are made into the same substituent (A = B), it becomes a standard when measuring decomposition temperature.

  As a method for lowering the deposition temperature, first, a device for weakening the intermolecular interaction can be considered. That is, by adding bulky and sterically hindering groups such as tertiary butyl groups in the structure, the distance between molecules is increased, the interaction between molecules is weakened, and vaporization is performed at a low temperature. It is a device to do. In this case, even if the decomposition temperature is low, it is possible to improve the vapor deposition property by lowering the vapor deposition temperature further. However, in this case, if the intermolecular distance is increased and the interaction is weakened, the charge transport capability in the organic film is also reduced, leading to a decrease in photoelectric conversion efficiency. Therefore, the introduction of excessive steric hindrance is an object of the present invention. Is not appropriate. In addition, introduction of a bulky group may lead to a decrease in decomposition temperature, and as a result, ΔTd may become small, which may be undesirable. In general, the larger the molecular weight, the heavier the molecules, so that vaporization becomes difficult and the deposition temperature rises. Even when the molecules are planar, the overlap between the molecules is large, the intermolecular distance tends to be small, and the intermolecular interaction is large, so that the deposition temperature tends to be large. From the above, the substituent has a structure that weakens the interaction between molecules to such an extent that does not impair the photoelectric conversion (having a group that reduces the planarity of the molecule and effectively sterically hinders), and has a molecular weight. Small, preferable long-wave absorption characteristics and low degradability are preferred.

  As a result of intensive studies, the inventors have found the following squarylium compounds that satisfy the above-described requirements, exhibit high photoelectric conversion efficiency, have low noise, and have good vapor deposition properties.

Hereinafter, the squarylium compound represented by the general formula (SQ-1) will be described.
General formula (SQ-1)

The substituent represented by A and B in the general formula (SQ-1) may be any substituent as long as the bonding position is sp ² carbon. Examples of the substituent include a group comprising an aryl group or a heterocyclic group. Examples of the substituent are preferably an aryl group, a heterocyclic group (which may be referred to as a heterocyclic group), or a methine group to which an aryl group or a heterocyclic group is bonded, and the heterocyclic carbon atom of the heterocyclic group and The case where the methine group is couple | bonded is preferable. The aryl group is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and examples thereof include phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl, and ferrocenyl. Can do. The heterocyclic group is preferably a monovalent group obtained by removing one hydrogen atom from a 5- or 6-membered, substituted or unsubstituted, aromatic or non-aromatic heterocyclic compound, and more preferably carbon. It is a 5- or 6-membered aromatic heterocyclic group of formula 3 to 30. For example, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl and the like can be mentioned. A cationic heterocyclic group such as 1-methyl-2-pyridinio and 1-methyl-2-quinolinio may also be used. In the case of a methine group to which an aryl group or a heterocyclic group is bonded, the above-mentioned ones are preferably used as the aryl group or the heterocyclic group, and the heterocyclic group includes a 2-cyclobutene-1,3-dione nucleus. An example thereof is a 2-cyclobutene-1,3-dione nucleus bonded to a methine group to which a heterocyclic group (for example, an indolenine nucleus) is bonded. The methine group is a substituted or unsubstituted methine group, and examples of the substituent of the methine group include W described below, and an alkyl group (preferably a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, for example, Methyl, ethyl, propyl, butyl, benzyl, phenethyl), an aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as phenyl, p-tolyl, naphthyl) and the like are preferable. In the case of a methine group bonded to a heterocyclic group, a methine group bonded to a carbon atom in the heterocyclic ring is preferred.
When the compound represented by the general formula (SQ-1) is used for infrared absorption, one of A and B is a methine group to which an indolenine nucleus (preferably bonded at the 2-position of the indolenine nucleus) is bound. A compound in which the other is a methine group to which a quinoline nucleus (preferably bonded at the 2-position or 4-position of the quinoline nucleus, more preferably at the 2-position) is bonded is preferable.

In the present invention, when a specific moiety is referred to as a “group”, the moiety may be unsubstituted or substituted with one or more (up to the maximum possible) substituents. Means good. For example, “alkyl group” means a substituted or unsubstituted alkyl group. In addition, the substituent that can be used in the compound in the present invention may be any substituent.

When such a substituent is W, the substituent represented by W is not particularly limited, and examples thereof include halogen atoms, alkyl groups (cycloalkyl groups, bicycloalkyl groups, tricycloalkyl groups). ), Alkenyl groups (including cycloalkenyl groups and bicycloalkenyl groups), alkynyl groups, aryl groups, heterocyclic groups (also referred to as heterocyclic groups), cyano groups, hydroxyl groups, nitro groups, carboxyl groups, Alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonyl Amino group, alkoxycarbonylamino group, Oxycarbonylamino group, sulfamoylamino group, alkylarylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group , Acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, Examples include a hydrazino group, a ureido group, a boronic acid group (—B (OH) ₂ ), a phosphato group (—OPO (OH) ₂ ), a sulfato group (—OSO ₃ H), and other known substituents.

Specifically, W represents a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group [a linear, branched, or cyclic substituted or unsubstituted alkyl group. They are alkyl groups (preferably alkyl groups having 1 to 30 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, t-butyl, n-octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, 2-ethylhexyl). A cycloalkyl group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, such as cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl), a bicycloalkyl group (preferably having 5 to 30 carbon atoms). A substituted or unsubstituted bicycloalkyl group, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo [1,2,2] heptan-2-yl, bicyclo [2,2,2] octane-3-yl), a tricyclo structure with more ring structures It is intended to encompass such. An alkyl group (for example, an alkyl group of an alkylthio group) in a substituent described below represents an alkyl group having such a concept, but also includes an alkenyl group and an alkynyl group. ], An alkenyl group [represents a linear, branched or cyclic substituted or unsubstituted alkenyl group. They are alkenyl groups (preferably substituted or unsubstituted alkenyl groups having 2 to 30 carbon atoms, such as vinyl, allyl, prenyl, geranyl, oleyl), cycloalkenyl groups (preferably substituted or substituted groups having 3 to 30 carbon atoms). An unsubstituted cycloalkenyl group, that is, a monovalent group obtained by removing one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms (for example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl), Bicycloalkenyl group (a substituted or unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom of a bicycloalkene having one double bond. For example, bicyclo [2,2,1] hept-2-en-1-yl, bicyclo 2,2,2] oct-2-en-4-yl). An alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, such as ethynyl, propargyl, trimethylsilylethynyl group), an aryl group (preferably a substituted or unsubstituted aryl having 6 to 30 carbon atoms) Groups such as phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl, ferrocenyl), heterocyclic groups (preferably 5- or 6-membered substituted or unsubstituted, aromatic or non-aromatic A monovalent group obtained by removing one hydrogen atom from a heterocyclic compound, and more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms, such as 2-furyl, 2- Examples include thienyl, 2-pyrimidinyl, 2-benzothiazolyl, etc. In addition, 1-methyl-2-pyridinio, 1- A cationic heterocyclic group such as til-2-quinolinio), a cyano group, a hydroxyl group, a nitro group, a carboxyl group, an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms) For example, methoxy, ethoxy, isopropoxy, t-butoxy, n-octyloxy, 2-methoxyethoxy), an aryloxy group (preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as phenoxy 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy, 2-tetradecanoylaminophenoxy), a silyloxy group (preferably a silyloxy group having 3 to 20 carbon atoms, for example, trimethylsilyloxy, t-butyl Dimethylsilyloxy), heterocyclic oxy group (preferably A substituted or unsubstituted heterocyclic oxy group having 2 to 30 carbon atoms, 1-phenyltetrazol-5-oxy, 2-tetrahydropyranyloxy), an acyloxy group (preferably a formyloxy group, a substitution having 2 to 30 carbon atoms) Or an unsubstituted alkylcarbonyloxy group, a substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms, such as formyloxy, acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, p-methoxyphenylcarbonyloxy), carbamoyl An oxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms such as N, N-dimethylcarbamoyloxy, N, N-diethylcarbamoyloxy, morpholinocarbonyloxy, N, N-di-n -Oct Ruaminocarbonyloxy, Nn-octylcarbamoyloxy), alkoxycarbonyloxy groups (preferably substituted or unsubstituted alkoxycarbonyloxy groups having 2 to 30 carbon atoms, such as methoxycarbonyloxy, ethoxycarbonyloxy, t-butoxycarbonyl Oxy, n-octylcarbonyloxy), aryloxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, such as phenoxycarbonyloxy, p-methoxyphenoxycarbonyloxy, p- n-hexadecyloxyphenoxycarbonyloxy), amino group (preferably amino group, substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, substituted or unsubstituted group having 6 to 30 carbon atoms) Arylamino groups such as amino, methylamino, dimethylamino, anilino, N-methyl-anilino, diphenylamino), ammonio groups (preferably ammonio groups, substituted or unsubstituted alkyls having 1 to 30 carbon atoms, aryl, hetero Ring-substituted ammonio groups such as trimethylammonio, triethylammonio, diphenylmethylammonio), acylamino groups (preferably formylamino groups, substituted or unsubstituted alkylcarbonylamino groups having 1 to 30 carbon atoms, carbon A substituted or unsubstituted arylcarbonylamino group of formula 6 to 30, for example, formylamino, acetylamino, pivaloylamino, lauroylamino, benzoylamino, 3,4,5-tri-n-octyloxyphenylcarbonylamino), A nocarbonylamino group (preferably a substituted or unsubstituted aminocarbonylamino having 1 to 30 carbon atoms, such as carbamoylamino, N, N-dimethylaminocarbonylamino, N, N-diethylaminocarbonylamino, morpholinocarbonylamino), An alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, such as methoxycarbonylamino, ethoxycarbonylamino, t-butoxycarbonylamino, n-octadecyloxycarbonylamino, N-methyl-methoxy; Carbonylamino), aryloxycarbonylamino group (preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms, such as phenoxycarbonylamino, p -Chlorophenoxycarbonylamino, mn-octyloxyphenoxycarbonylamino), a sulfamoylamino group (preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms, such as sulfamoylamino, N, N-dimethylaminosulfonylamino, Nn-octylaminosulfonylamino), alkyl and arylsulfonylamino groups (preferably a substituted or unsubstituted alkylsulfonylamino group having 1 to 30 carbon atoms, 6 to 30 carbon atoms) A substituted or unsubstituted arylsulfonylamino group such as methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, 2,3,5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino), mercapto group, a Kirthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms such as methylthio, ethylthio, n-hexadecylthio), arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms such as , Phenylthio, p-chlorophenylthio, m-methoxyphenylthio), a heterocyclic thio group (preferably a substituted or unsubstituted heterocyclic thio group having 2 to 30 carbon atoms, such as 2-benzothiazolylthio, 1-phenyl Tetrazol-5-ylthio), a sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms, such as N-ethylsulfamoyl, N- (3-dodecyloxypropyl) sulfamoyl, N, N- Dimethylsulfamoyl, N-acetylsulfamoy N-benzoylsulfamoyl, N- (N′-phenylcarbamoyl) sulfamoyl), sulfo group, alkyl and arylsulfinyl group (preferably substituted or unsubstituted alkylsulfinyl group having 1 to 30 carbon atoms, 6 to 30 Substituted or unsubstituted arylsulfinyl groups such as methylsulfinyl, ethylsulfinyl, phenylsulfinyl, p-methylphenylsulfinyl), alkyl and arylsulfonyl groups (preferably substituted or unsubstituted alkylsulfonyl having 1 to 30 carbon atoms) A group, a substituted or unsubstituted arylsulfonyl group of 6 to 30, for example, methylsulfonyl, ethylsulfonyl, phenylsulfonyl, p-methylphenylsulfonyl), an acyl group (preferably a formyl group, 2 to 3 carbon atoms) Substituted or unsubstituted alkylcarbonyl groups, substituted or unsubstituted arylcarbonyl groups having 7 to 30 carbon atoms, or heterocyclic carbonyl groups bonded to carbonyl groups at substituted or unsubstituted carbon atoms having 4 to 30 carbon atoms For example, acetyl, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyloxyphenylcarbonyl, 2-pyridylcarbonyl, 2-furylcarbonyl), an aryloxycarbonyl group (preferably having 7 to 30 carbon atoms) A substituted or unsubstituted aryloxycarbonyl group, for example, phenoxycarbonyl, o-chlorophenoxycarbonyl, m-nitrophenoxycarbonyl, pt-butylphenoxycarbonyl), an alkoxycarbonyl group (preferably a substituent having 2 to 30 carbon atoms) if Or an unsubstituted alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, n-octadecyloxycarbonyl), a carbamoyl group (preferably a substituted or unsubstituted carbamoyl having 1 to 30 carbon atoms such as carbamoyl N-methylcarbamoyl, N, N-dimethylcarbamoyl, N, N-di-n-octylcarbamoyl, N- (methylsulfonyl) carbamoyl), aryl and heterocyclic azo groups (preferably having 6 to 30 carbon atoms substituted or Unsubstituted arylazo group, substituted or unsubstituted heterocyclic azo group having 3 to 30 carbon atoms, such as phenylazo, p-chlorophenylazo, 5-ethylthio-1,3,4-thiadiazol-2-ylazo), imide group (Preferably, N-succiny N-phthalimide), phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, such as dimethylphosphino, diphenylphosphino, methylphenoxyphosphino), phosphinyl group (preferably carbon A substituted or unsubstituted phosphinyl group having 2 to 30 carbon atoms, such as phosphinyl, dioctyloxyphosphinyl, diethoxyphosphinyl), a phosphinyloxy group (preferably a substituted or unsubstituted carbon atom having 2 to 30 carbon atoms) A phosphinyloxy group such as diphenoxyphosphinyloxy, dioctyloxyphosphinyloxy), a phosphinylamino group (preferably a substituted or unsubstituted phosphinylamino group having 2 to 30 carbon atoms such as Dimethoxyphosphinylamino, dimethylaminophos Ynylamino), phosphor group, silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, such as trimethylsilyl, triethylsilyl, triisopropylsilyl, t-butyldimethylsilyl, phenyldimethylsilyl), hydrazino group (Preferably a substituted or unsubstituted hydrazino group having 0 to 30 carbon atoms, such as trimethylhydrazino), or a ureido group (preferably a substituted or unsubstituted ureido group having 0 to 30 carbon atoms such as N, N-dimethyl) Urei

D).

  In addition, two Ws can be combined to form a ring (aromatic or non-aromatic hydrocarbon ring or heterocyclic ring. These can be further combined to form a polycyclic fused ring. For example, a benzene ring or naphthalene. Ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, Indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, Phenanthroline ring, thian Ren ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, or a phenazine ring.) May also be formed.

Among the above substituents W, those having a hydrogen atom may be substituted with the above groups by removing this. Examples of such substituents include a —CONHSO ₂ — group (sulfonylcarbamoyl group, carbonylsulfamoyl group), —CONHCO— group (carbonylcarbamoyl group), —SO ₂ NHSO ₂ — group (sulfonylsulfamoyl group). ). More specifically, an alkylcarbonylaminosulfonyl group (eg, acetylaminosulfonyl), an arylcarbonylaminosulfonyl group (eg, benzoylaminosulfonyl group), an alkylsulfonylaminocarbonyl group (eg, methylsulfonylaminocarbonyl), or arylsulfonyl An aminocarbonyl group (for example, p-methylphenylsulfonylaminocarbonyl) is mentioned.

In the present invention, the compound represented by General Formula (SQ-1) is preferably a compound selected from General Formula (SQ-2).
General formula (SQ-2)

The substituent represented by R ^{1 to} R ⁸ in the general formula (SQ-2) may be any substituent, and examples thereof include the aforementioned W. R ¹ is preferably a hydrogen atom, a methyl group, or a phenyl group, more preferably a hydrogen atom or a methyl group. R ² is preferably an alkyl group (methyl, ethyl, etc.) or a phenyl group, more preferably a methyl group. R ³ and R ⁴ are preferably each independently an alkyl group (methyl, ethyl, propyl, butyl, etc.) or a phenyl group, and more preferably both are methyl groups. R ^{5 to} R ⁸ are preferably all hydrogen atoms, or R ⁵ and R ⁶ , R ⁶ and R ⁷ , R ⁷ and R ⁸ are benzo-fused, and the rest is a hydrogen atom. More preferably, all are hydrogen atoms. B has the same meaning as in the general formula SQ-1, but for infrared absorption, it may be an unsubstituted methine group to which a quinoline nucleus, a pyrylium nucleus, a thiopyrylium nucleus, an azulene nucleus, and a dihydroperimidine nucleus are bonded. Preferably, it is an unsubstituted methine group to which a quinoline nucleus is bonded, and a preferable bonding position is the same as in the case of the general formula (SQ-1).

In the present invention, the compound represented by General Formula (SQ-2) is preferably a compound selected from General Formula (SQ-3).
General formula (SQ-3)

In General Formula (SQ-3), B has the same meaning as in General Formula SQ-1, and the preferred range is also the same.
In particular, the indolenine nucleus structure bonded to the methine group in the general formula (SQ-3) is important, and this structure is considered to have the effect of improving the photoelectric conversion efficiency, lowering the deposition temperature, and raising the decomposition temperature. . From the viewpoint of vapor deposition properties, a simple indolenine structure such as the general formula (SQ-3) is preferred which has a low molecular weight for reducing the vapor deposition temperature and does not introduce a group for increasing the decomposability.
In order to increase the absorption wavelength for infrared absorption, the structure of the substituent B is important. However, even those that exhibit long-wave absorption are inappropriate because of high decomposability because the vapor deposition performance is reduced. About the ease of decomposition | disassembly of each substituent, when the both ends of general formula (SQ-1) are made into the same substituent (A = B), it is preferable that it is 200 degreeC or more.
Examples of the compounds represented by the general formulas (SQ-1), (SQ-2), and (SQ-3) used in the present invention are shown below. However, the present invention is not limited to the following examples.

The compounds represented by the above general formulas (SQ-1), (SQ-2) and (SQ-3) and the specific example compounds are represented by one chemical formula. Therefore, it is needless to say that those represented by other indications are also included in the present invention.
The compounds shown in the above specific examples can be synthesized with reference to known literature (Dyes and Pigments, 21 (1993), 227-234, etc.).
A photoelectric conversion element including a photoelectric conversion part including a photoelectric conversion film containing the compounds represented by the general formulas (SQ-1), (SQ-2), and (SQ-3) as an organic photoelectric conversion material will be described.
Hereinafter, embodiments of the photoelectric conversion element of the present invention will be described with reference to the drawings. In the following description, light in the red (R) wavelength region (R light) generally indicates light in the wavelength range of 550 to 650 nm, and light in the green (G) wavelength region (G light) Generally indicates light in the wavelength range of 450 to 610 nm, blue (B) wavelength light (B light) generally indicates light in the wavelength range of 400 to 520 nm, and in the infrared range Light in the wavelength range (infrared light) generally indicates light in the wavelength range of 680 to 10000 nm, and light in the visible wavelength range (visible light) generally has a wavelength in the range of 400 to 650 nm. Show light.

(First embodiment of photoelectric conversion element)
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of the photoelectric conversion element according to the first embodiment of the present invention.
1 includes a lower electrode 11, an upper electrode 13 facing the lower electrode 11, and a photoelectric conversion film 12 provided between the lower electrode 11 and the upper electrode 13. At least. The photoelectric conversion element shown in FIG. 1 is used with light incident from above the upper electrode 13.

The upper electrode 13 is a transparent electrode made of a conductive material that is transparent to light (visible light and infrared light) in a range that combines the visible region and the infrared region (wavelength of 400 nm or more). In this specification, “transparent to light of a certain wavelength” means that 70% or more of light of that wavelength is transmitted. A bias voltage is applied to the upper electrode 13 by a wiring (not shown). The polarity of the bias voltage is determined so that, of the charges generated in the photoelectric conversion film 12, electrons move to the upper electrode 13 and holes move to the lower electrode 11. Of course, the bias voltage may be set so that, of the charges generated in the photoelectric conversion film 12, holes move to the upper electrode 13 and electrons move to the lower electrode 11. Further, the bias voltage is obtained by dividing the value by the distance between the lower electrode 11 and the upper electrode 13 so as to be between 1.0 × 10 ⁵ V / cm and 1.0 × 10 ⁷ V / cm. Preferably, it is between 1.0 × 10 ⁴ V / cm and 1.0 × 10 ⁶ V / cm. With this bias voltage, it is possible to efficiently move charges to the upper electrode 13 and to extract a signal corresponding to the charges to the outside.

  Since the lower electrode 11 is applied to a solid-state imaging device (hereinafter referred to as a visible / infrared imaging device) capable of simultaneously capturing a visible image and capturing an infrared image, the lower electrode 11 also includes a portion of incident light below it. Since it is necessary to transmit visible light, it is desirable to use a transparent electrode like the upper electrode 11. However, the lower electrode 11 does not have to be transparent to light in the infrared region, and may be transparent to at least light in the visible region.

  The photoelectric conversion film 12 has an absorption peak of an absorption spectrum in a range including a visible region and an infrared region (light having a wavelength of 400 nm or more) in the infrared region, and generates an electric charge corresponding to the absorbed infrared light. It is the film | membrane comprised including.

  As such an organic photoelectric conversion material, the squalium dye is preferably used.

In order to apply the photoelectric conversion element including the photoelectric conversion part A configured as described above to the visible / infrared imaging element, the photoelectric conversion part A has the photoelectric conversion film 12 to obtain information other than human visibility. The wavelength of the absorption peak in the infrared region of the organic photoelectric conversion material contained is preferably 650 nm or more (preferably 700 nm or more), and the absorptance at that wavelength is preferably 50% or more, more preferably 80% or more. is there. Further, in order to sufficiently obtain a visible light signal below the photoelectric conversion unit A, the photoelectric conversion unit A preferably transmits 50% or more of visible light as a whole, and more preferably 75% or more. The visible light transmittance of the photoelectric conversion part A can be adjusted by appropriately selecting the constituent materials and the thicknesses of the upper electrode 13, the lower electrode 11, and the photoelectric conversion film 12.
In the present invention, “absorptivity and transmittance in a certain wavelength region α to β nm” means “integration in the wavelength region α to β nm when the absorptivity and transmittance are 100% for the wavelength region α to β nm”. It can be expressed as Y / X × 100, where X is the value of X, the absorptance of each wavelength, and the integral value of transmittance in the wavelength range α to β nm.

  The light transmittance of the lower electrode 11 and the upper electrode 13 greatly influences the infrared light absorption rate and the visible light absorption rate of the lower layer. When incident light is absorbed and reflected by the lower electrode 11 and the upper electrode 13, the absolute amount of light reaching the lower layer is reduced, which directly leads to a reduction in sensitivity. In order to transmit more light to the lower layer and increase the sensitivity in the photoelectric conversion film 12, the transmittance of visible light and infrared light of the upper electrode 13 is preferably 90% or more, more preferably 95% or more. It is. Moreover, in order to transmit more visible light to the lower layer and increase the sensitivity of the visible light detection element provided below the photoelectric conversion element, the visible light transmittance of the lower electrode 11 is preferably 90% or more. Preferably it is 95% or more.

As a material of the lower electrode 11 and the upper electrode 13 satisfying such conditions, a transparent conductive oxide (TCO) having a high transmittance for visible light and infrared light and a small resistance value is preferably used. Can do. A metal thin film such as Au can also be used. However, if an attempt is made to obtain a transmittance of 90% or more, the resistance value increases drastically, so TCO is preferable. In particular, ITO, IZO, AZO, FTO, SnO ₂ , TiO ₂ , ZnO _{2 and the} like can be preferably used as TCO.

  When a transparent conductive material such as TCO is formed on the photoelectric conversion film 12 to form the upper electrode 13, a DC short circuit or an increase in leakage current may occur. One reason for this is considered to be that fine cracks introduced into the photoelectric conversion film 12 are covered by a dense film such as TCO, and conduction between the transparent conductive material film on the opposite side is increased. Therefore, in the case of an electrode having a poor film quality such as Al, an increase in leakage current is unlikely to occur. By controlling the film thickness of the transparent conductive material film with respect to the thickness of the photoelectric conversion film 12 (that is, the depth of cracks), an increase in leakage current can be largely suppressed. The thickness of the transparent conductive material film, that is, the thickness of the upper electrode 13 is desirably 1/5 or less, preferably 1/10 or less of the thickness of the photoelectric conversion film 12.

  Usually, when the transparent conductive material film is made thinner than a certain range, the resistance value increases rapidly. However, in the photoelectric conversion element of the present invention, the sheet resistance is preferably 100 to 10,000 Ω / □ and can be thinned. The degree of freedom in the film thickness range is large. In addition, the thinner the transparent conductive material film is, the less light is absorbed, and the light transmittance is generally increased. The increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion film 12 and increases the photoelectric conversion performance. In consideration of suppression of leakage current, increase in resistance value of thin film, and increase in transmittance accompanying thinning of the transparent conductive material film, the thickness of the transparent conductive material film is preferably 5 to 100 nm, More preferably, it is 5 to 20 nm.

  When the surface of the lower electrode 11 has irregularities, or when dust adheres to the surface of the lower electrode 11, a low molecular organic photoelectric conversion material is deposited thereon to form the photoelectric conversion film 12. The conversion film 12 is likely to have a fine crack or a portion where the photoelectric conversion film 12 is only formed thin. At this time, if the upper electrode 13 is further formed thereon, the crack is covered by the transparent conductive material film, and the photoelectric conversion film 12 and the upper electrode 13 are partially close to each other. Prone to occur. In particular, when TCO is used as the upper electrode 13, the tendency is remarkable. As one method for preventing such an increase in leakage current, it is preferable to form an undercoat film on the lower electrode 11 to relieve unevenness. As the undercoat film, a method of forming a polymer material such as polyaniline, polythiophene, polypyrrole, polycarbazole, PTPDES, or PTPDK by a spin coating method is highly effective. When the photoelectric conversion film 12 is to be formed in a vacuum by vapor deposition or the like in order to prevent impurities from being mixed and to make a more evenly uniform laminated film, an amorphous film is used as the undercoat layer. It is preferable.

In addition, as a combination of the lower electrode 11, the organic photoelectric conversion material, and the upper electrode 13 capable of setting the visible light transmittance of the photoelectric conversion portion A to 50% or more, the lower electrode is used as described in Examples described later. 11 and the upper electrode 13 may be ITO, and the organic photoelectric conversion material may be tin phthalocyanine. In addition to this, the lower electrode 11 and the upper electrode 13 are respectively IZO, AZO, FTO, SnO ₂ , TiO ₂ , or ZnO ₂ , and the organic photoelectric conversion material is any one of the above-described dyes, so that the photoelectric conversion unit A The visible light transmittance of 50% or more can be realized.

(Second Embodiment of Photoelectric Conversion Element)
FIG. 2 is a schematic cross-sectional view showing a schematic configuration of the photoelectric conversion element according to the second embodiment of the present invention.
The photoelectric conversion element shown in FIG. 2A is a semiconductor substrate K such as silicon, a visible light photoelectric conversion unit B stacked above the semiconductor substrate K, and a layer stacked above the visible light photoelectric conversion unit B in FIG. The photoelectric conversion part A shown is provided.

  The visible light photoelectric conversion unit B has substantially the same configuration as that of the photoelectric conversion unit A. As an organic photoelectric conversion material constituting the photoelectric conversion film 12 of the photoelectric conversion unit A, a range that combines the visible region and the infrared region (wavelength of 400 nm or more). The material having an absorption peak of the absorption spectrum in the visible range in the visible region and generating a charge according to the absorbed light is used.

  In the semiconductor substrate K, there is formed a storage unit 3 for storing charges generated in the photoelectric conversion film 12 of the photoelectric conversion unit A and transferred to the upper electrode 13, and the storage unit 3 and the upper electrode 13 are connected to each other. The parts 6 are electrically connected. Further, in the semiconductor substrate K, there is formed a storage portion 4 for storing charges generated in the photoelectric conversion film of the photoelectric conversion portion B and transferred to the upper electrode, and the storage portion 4 and the upper electrode are connected to each other. 7 is electrically connected.

  The photoelectric conversion element illustrated in FIG. 2B includes a semiconductor substrate K such as silicon and the photoelectric conversion unit A illustrated in FIG. 1 stacked above the semiconductor substrate K. In the semiconductor substrate K below the photoelectric conversion part A, the absorption peak of the absorption spectrum in the range including the visible region and the infrared region (wavelength of 400 nm or more) is in the visible region, and a charge corresponding to the absorbed light is generated. A visible light photoelectric conversion unit C is formed. In addition, in the semiconductor substrate K, a storage unit 3 ′ for storing charges generated in the photoelectric conversion film 12 of the photoelectric conversion unit A and transferred to the upper electrode 13 is formed. The storage unit 3 ′ and the upper electrode are formed. 13 is electrically connected by a connecting portion 6 '. The visible light photoelectric conversion unit C is configured by, for example, a known pn junction photodiode.

  2A and 2B, a signal corresponding to the infrared light is acquired by the electric charge generated in the photoelectric conversion unit A installed in the upper layer, and the signal is installed below the photoelectric conversion unit A. It is possible to realize a photoelectric conversion element that can acquire a signal corresponding to visible light by the electric charges generated in the photoelectric conversion unit B and the photoelectric conversion unit C.

  In the case of the configuration of FIG. 2A, for example, a signal corresponding to infrared light and a signal corresponding to G light are configured by configuring the photoelectric conversion film of the photoelectric conversion unit B with a quinacridone-based organic material (for example, quinacridone). Can be obtained at the same time. For this reason, a number of photoelectric conversion elements in FIG. 2A are two-dimensionally arranged on the same plane, and a signal readout circuit such as a CCD or CMOS circuit that reads out a signal corresponding to the charge generated in each photoelectric conversion element is used as a semiconductor. By providing the substrate K, it is possible to realize an infrared / visible imaging element capable of simultaneously capturing an infrared image corresponding to infrared light and a monochrome image corresponding to G light.

  In addition, a photoelectric conversion element in which the photoelectric conversion film of the photoelectric conversion part B is a quinacridone-based organic material (for example, quinacridone), and a photoelectric conversion element in which the photoelectric conversion film of the photoelectric conversion part B is a phthalocyanine-based organic material (for example, zinc phthalocyanine) CCD or CMOS which reads a signal corresponding to the electric charge generated in each photoelectric conversion element by arranging a large number of photoelectric conversion elements in which the photoelectric conversion film of the photoelectric conversion part B is a porphyrin organic compound two-dimensionally on the same plane By providing a signal readout circuit such as a circuit on the semiconductor substrate K, it is possible to simultaneously capture an infrared image corresponding to infrared light and a color image corresponding to R, G, B light by known signal processing. An infrared / visible imaging device can be realized.

  In FIG. 2A, two more photoelectric conversion units B are provided between the photoelectric conversion unit A and the photoelectric conversion unit B, or between the semiconductor substrate K and the photoelectric conversion unit B. By making the material of the photoelectric conversion film of the photoelectric conversion part B into quinacridone, zinc phthalocyanine, and a porphyrin-based organic compound, the photoelectric conversion part A generates signals corresponding to infrared light from the three photoelectric conversion parts B. A signal corresponding to the R, G, B light can be obtained. For this reason, a number of photoelectric conversion elements in FIG. 2A are two-dimensionally arranged on the same plane, and a signal readout circuit such as a CCD or CMOS circuit that reads out a signal corresponding to the charge generated in each photoelectric conversion element is used as a semiconductor. By providing the substrate K, it is possible to realize an infrared / visible imaging element capable of simultaneously capturing an infrared image corresponding to infrared light and a color image corresponding to R, G, B light. . Of course, a configuration in which one or more photoelectric conversion units B are provided between the photoelectric conversion unit A and the photoelectric conversion unit B or between the semiconductor substrate K and the photoelectric conversion unit B is also possible depending on the use application. It is.

  In the case of the configuration of FIG. 2B, the photoelectric conversion unit C itself is a pn junction photodiode and basically has sensitivity to light having a wavelength of 1100 nm or less, and therefore the infrared light absorbed by the photoelectric conversion unit A is absorbed. It has sensitivity for light other than light. When there is nothing other than the photoelectric conversion unit A that absorbs light, the light incident on the photoelectric conversion unit C is the entire light having a wavelength transmitted through the photoelectric conversion unit A, and a signal corresponding to infrared light and visible light. Can be obtained simultaneously. For this reason, a large number of photoelectric conversion elements in FIG. 2B are two-dimensionally arranged on the same plane, and a signal readout circuit such as a CCD or CMOS circuit that reads out a signal corresponding to the charge generated in each photoelectric conversion element is used as a semiconductor. By providing the substrate K, it is possible to realize an infrared / visible imaging element capable of simultaneously capturing an infrared image corresponding to infrared light and a monochrome image corresponding to visible light.

  For the photoelectric conversion portion C, as described in Japanese Patent No. 5965875, a pn junction surface is formed at each of a depth that absorbs R light, a depth that absorbs G light, and a depth that absorbs B light. If the photoelectric conversion unit C is formed by stacking three photoelectric conversion units C in the depth direction so as to obtain the signals corresponding to the respective absorption wavelengths, the visible light transmitted through the photoelectric conversion unit A can be obtained. A color signal can be acquired from light, and a signal corresponding to infrared light and a signal corresponding to R, G, B light can be acquired simultaneously. Of course, a configuration in which two or four or more photoelectric conversion units C are stacked in the depth direction in the semiconductor substrate K below the photoelectric conversion unit A is also possible depending on the intended use.

  If a spectral filter that transmits light in a specific wavelength region is installed above the photoelectric conversion unit A, the light incident on the photoelectric conversion unit C can be dispersed. As the spectral filter, it is possible to use a primary color system or a complementary color system color filter used in a normal CCD or CMOS color image sensor. A color filter used in a CCD or CMOS color image sensor generally has a characteristic of transmitting a part of infrared light. Therefore, even when the color filter is arranged above the photoelectric conversion unit A, infrared light is transmitted to the photoelectric conversion unit A. Can be incident.

  For example, a photoelectric conversion element provided with an R color filter that transmits a part of R light and infrared light above the photoelectric conversion unit A in FIG. 2B, and a G conversion above the photoelectric conversion unit A in FIG. A photoelectric conversion element provided with a G color filter that transmits part of light and infrared light, and a B color filter that transmits part of B light and infrared light above the photoelectric conversion part A in FIG. A large number of the photoelectric conversion elements provided are arranged on the same plane, and a signal reading circuit such as a CCD or a CMOS circuit for reading a signal corresponding to the electric charge generated in each photoelectric conversion element is provided on the semiconductor substrate K. By the signal processing, an infrared / visible imaging element capable of capturing an infrared image and a color image can be realized.

  According to the photoelectric conversion elements shown in FIGS. 2 (a) and 2 (b), the photoelectric conversion units for detecting different lights are stacked in the vertical direction. Almost all can be taken out as a signal, and since there is no loss of light quantity, high sensitivity can be realized. Furthermore, in a normal Si photoelectric conversion device, an infrared cut filter is provided to cut a signal due to infrared light, but the uppermost photoelectric conversion unit A can play a part or all of the role. Therefore, when applied to an image sensor, an effect of eliminating part of the infrared cut filter is obtained.

2 (a) and 2 (b), one or more photoelectric conversion elements B or photoelectric conversion units C are stacked below the photoelectric conversion unit A, but as shown in FIG. 2 (c). In the semiconductor substrate K below the photoelectric conversion unit A, a plurality of photoelectric conversion units C are arranged in a direction perpendicular to the incident direction of light incident on the semiconductor substrate K (a direction parallel to the surface of the semiconductor substrate K). The structure which was made can also be considered. For example, three pn junction photodiodes are arranged in the vertical direction as the photoelectric conversion unit C in the semiconductor substrate K below the photoelectric conversion unit A, and an R color filter and a G color filter are disposed above each of the three pn junction photodiodes. , B color filter is arranged. Then, by arranging a large number of such photoelectric conversion elements on the same plane and providing a signal reading circuit such as a CCD or CMOS circuit on the semiconductor substrate K for reading a signal corresponding to the charge generated in each photoelectric conversion element, It is possible to realize an infrared / visible imaging element capable of simultaneously capturing an infrared image and a color image in which each photoelectric conversion element and pixel have a one-to-one correspondence.
The pixel sizes of the photoelectric conversion unit A and the photoelectric conversion units B and C can be assigned to different sizes.

  In FIG. 2C, a plurality of photoelectric conversion units C correspond to one photoelectric conversion unit A, but the incident side is a plurality of conversion units and the substrate side is one conversion unit. In addition, as shown in FIG. 2D, a configuration in which one photoelectric conversion unit C corresponds to two photoelectric conversion units A can be used depending on usage.

  In the configuration example illustrated in FIG. 2, the photoelectric conversion unit A and the photoelectric conversion unit B are configured such that light transmitted through the photoelectric conversion unit A enters the photoelectric conversion unit B. Needless to say, and are overlapped in plan view. Similarly, in the photoelectric conversion unit A and the photoelectric conversion unit C, the photoelectric conversion unit A and the photoelectric conversion unit C overlap in plan view so that light transmitted through the photoelectric conversion unit A enters the photoelectric conversion unit C. Needless to say.

  Next, a more preferable form of the photoelectric conversion unit A shown in FIG. 1 will be described. The photoelectric conversion unit A described below has a configuration as shown in FIG. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals.

  In the photoelectric conversion part A, the voltage application method and the element material configuration were performed so as to collect the signal charges having a smaller hole and electron transportability in the organic film from the upper electrode 13 side on the light incident side. This is preferable because the photoelectric conversion efficiency is large and the spectral sensitivity becomes sharp. In the photoelectric conversion film 12 of the photoelectric conversion part A, light absorption mainly occurs on the light incident side. Therefore, by collecting charges having low transportability from the upper electrode 13 closer to the light incident side, the charge transport distance. Therefore, charge deactivation during transportation is reduced and efficiency is increased. If the charge is collected in the direction opposite to the above, the longer the absorption rate, the longer the transport distance because the charge generation part is closer to the upper electrode 13 side. At wavelengths where the absorption rate of light reaching the back of the film is low and the absorption rate is low, the charge generation site is at the back of the film, which shortens the transport distance and increases the collection efficiency. Spectral sensitivity becomes broad. In an organic film, there are many materials having a large hole transport ability. In this case, a voltage is applied so as to collect electrons from the upper electrode 13, and holes are collected from the lower electrode 11 to generate a signal. A format for storing, transferring and reading is desirable.

  Hereinafter, a case where electrons are collected from the upper electrode 13 will be described. When collecting holes from the upper electrode 13, it is only necessary to reverse the order of film formation except for the undercoat film 121 and the work function adjusting film 126. The work function adjusting film 126 may be changed so as to select a work function having a large work function.

  As shown in FIG. 3, an undercoat film 121 and an electron blocking film 122 are provided between the photoelectric conversion film 12 and the lower electrode 11 of the photoelectric conversion unit A, and between the photoelectric conversion film 12 and the upper electrode 13. Is preferably provided with a hole blocking film 124, a hole blocking / buffer film 125, and a work function adjusting film 126.

  The organic photoelectric conversion material constituting the photoelectric conversion film 12 preferably contains at least one of an organic p-type semiconductor and an organic n-type semiconductor.

  The organic p-type semiconductor (compound) is a donor-type organic semiconductor (compound), which is mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound. For example, triarylamine compound, benzidine compound, pyrazoline compound, styrylamine compound, hydrazone compound, triphenylmethane compound, carbazole compound, polysilane compound, thiophene compound, phthalocyanine compound, cyanine compound, merocyanine compound, oxonol compound, polyamine compound, indole Compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), nitrogen-containing heterocyclic compounds The metal complex etc. which it has as can be used. Not limited to this, as described above, any organic compound having an ionization potential smaller than that of the organic compound used as the n-type (acceptor property) compound may be used as the donor organic semiconductor.

  Organic n-type semiconductors (compounds) are acceptor organic semiconductors (compounds), which are mainly represented by electron-transporting organic compounds and refer to organic compounds that easily accept electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound. For example, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), 5- to 7-membered heterocyclic compounds containing nitrogen atoms, oxygen atoms, and sulfur atoms (E.g. pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, Benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, o Metal complexes having ligands such as saziazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and nitrogen-containing heterocyclic compounds. Etc. Note that the present invention is not limited thereto, and as described above, any organic compound having an electron affinity higher than that of the organic compound used as the donor organic compound may be used as the acceptor organic semiconductor.

  Next, the metal complex compound will be described. The metal complex compound is a metal complex having a ligand having at least one nitrogen atom or oxygen atom or sulfur atom coordinated to the metal, and the metal ion in the metal complex is not particularly limited, but preferably beryllium ion, magnesium Ion, aluminum ion, gallium ion, zinc ion, indium ion, or tin ion, more preferably beryllium ion, aluminum ion, gallium ion, or zinc ion, and still more preferably aluminum ion or zinc ion. As the ligand contained in the metal complex, there are various known ligands. For example, “Photochemistry and Photophysics of Coordination Compounds” published by Springer-Verlag H. Yersin in 1987, “Organometallic Chemistry— Examples of the ligands described in “Basics and Applications—” published by Akio Yamamoto, 1982, etc.

  The ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Or a bidentate or higher ligand, preferably a bidentate ligand such as a pyridine ligand, a bipyridyl ligand, a quinolinol ligand, a hydroxyphenylazole ligand (hydroxyphenyl) Benzimidazole, hydroxyphenylbenzoxazole ligand, hydroxyphenylimidazole ligand)), alkoxy ligand (preferably 1-30 carbon atoms, more preferably 1-20 carbon atoms, particularly preferably carbon 1-10, for example, methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), aryloxy ligands Preferably it has 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl Oxy, 4-biphenyloxy, etc.), heteroaryloxy ligands (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyl. Oxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, etc.), alkylthio ligands (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio, etc.), arylthio ligands (preferably having 6 to 30 carbon atoms, more preferred) Has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, etc.), a heterocyclic substituted thio ligand (preferably 1 to 30 carbon atoms, more preferably 1 to carbon atoms). 20, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio and the like, or siloxy ligand (preferably Has 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group. More preferably a nitrogen-containing heterocyclic ligand, an aryloxy ligand, a heteroaryloxy group, or a siloxy ligand, Preferably, a nitrogen-containing heterocyclic ligand, an aryloxy ligand, or a siloxy ligand is used.

  The photoelectric conversion film 12 includes a p-type semiconductor layer and an n-type semiconductor layer, at least one of the p-type semiconductor and the n-type semiconductor is an organic semiconductor, and the p-type semiconductor layer is interposed between the semiconductor layers. It is preferable to have a bulk heterojunction structure layer including an n-type semiconductor and an n-type semiconductor as an intermediate layer. In such a case, by including a bulk heterojunction structure in the photoelectric conversion film 12, it is possible to compensate for the shortcoming of the short carrier diffusion length of the photoelectric conversion film 12 and to improve the photoelectric conversion efficiency. The bulk heterojunction structure is described in detail in Japanese Patent Application No. 2004-080639.

  Further, the photoelectric conversion film 12 preferably has a structure having two or more repeating structures (tandem structures) of a pn junction layer formed of a p-type semiconductor layer and an n-type semiconductor layer, and more preferably, In this case, a thin layer of conductive material is inserted between the repeated structures. The number of repeating structures (tandem structures) of the pn junction layer may be any number, but is preferably 2 to 50, more preferably 2 to 30, particularly preferably 2 or 10 in order to increase the photoelectric conversion efficiency. It is. Silver or gold is preferable as the conductive material, and silver is most preferable. The tandem structure is described in detail in Japanese Patent Application No. 2004-079930.

  The photoelectric conversion film 12 has a p-type semiconductor layer, an n-type semiconductor layer (preferably a mixed / dispersed (bulk heterojunction structure) layer), and is formed on at least one of the p-type semiconductor and the n-type semiconductor. The case where an organic compound whose orientation is controlled is preferable, and the case where an organic compound whose orientation is controlled (possible) is included in both the p-type semiconductor and the n-type semiconductor is more preferable. As this organic compound, those having π-conjugated electrons are preferably used, and it is more preferable that the π-electron plane is oriented at an angle close to parallel rather than perpendicular to the substrate (electrode substrate). The angle with respect to the substrate is preferably 0 ° or more and 80 ° or less, more preferably 0 ° or more and 60 ° or less, further preferably 0 ° or more and 40 ° or less, and further preferably 0 ° or more and 20 ° or less. Particularly preferably, it is 0 ° or more and 10 ° or less, and most preferably 0 ° (that is, parallel to the substrate). As described above, the organic compound layer whose orientation is controlled may be partially included in the entire photoelectric conversion film 12, but preferably, the ratio of the portion whose orientation is controlled with respect to the entire photoelectric conversion film 12 is 10% or more, more preferably 30% or more, more preferably 50% or more, further preferably 70% or more, particularly preferably 90% or more, and most preferably 100%. Such a state compensates for the short carrier diffusion length of the photoelectric conversion film 12 by controlling the orientation of the organic compound contained in the photoelectric conversion film 12, and improves the photoelectric conversion efficiency.

  In the case where the orientation of the organic compound is controlled, it is more preferable that the heterojunction plane (for example, the pn junction plane) is not parallel to the substrate. It is more preferable that the heterojunction plane is oriented not at a parallel to the substrate (electrode substrate) but at an angle close to the vertical. The angle with respect to the substrate is preferably 10 ° or more and 90 ° or less, more preferably 30 ° or more and 90 ° or less, further preferably 50 ° or more and 90 ° or less, and further preferably 70 ° or more and 90 ° or less. Particularly preferably, it is 80 ° or more and 90 ° or less, and most preferably 90 ° (that is, perpendicular to the substrate). The organic compound layer whose heterojunction surface is controlled as described above may be partially included in the entire photoelectric conversion film 12. Preferably, the ratio of the portion whose orientation is controlled with respect to the entire photoelectric conversion film 12 is 10% or more, more preferably 30% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably. 90% or more, most preferably 100%. In such a case, the area of the heterojunction surface in the photoelectric conversion film 12 is increased, the amount of carriers such as electrons, holes, and electron-hole pairs generated at the interface is increased, and the photoelectric conversion efficiency can be improved. In the above-described photoelectric conversion film in which the orientation of both the heterojunction plane and the π-electron plane of the organic compound is controlled, the photoelectric conversion efficiency can be particularly improved. These states are described in detail in Japanese Patent Application No. 2004-079931. In terms of light absorption, the thickness of the organic dye layer is preferably as large as possible, but considering the ratio that does not contribute to charge separation, the thickness of the organic dye layer is preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, Especially preferably, it is 80 nm or more and 200 nm or less.

In the case where a polymer compound is used as at least one of the p-type semiconductor (compound) and the n-type semiconductor (compound), it is preferable to form the film by a wet film forming method that is easy to prepare. When a dry film formation method such as vapor deposition is used, it is difficult to use a polymer because it may be decomposed, and an oligomer thereof can be preferably used instead. On the other hand, when a low molecule is used, a dry film forming method is preferably used, and a vacuum deposition method is particularly preferably used. The vacuum deposition method is basically based on the method of heating compounds such as resistance heating deposition method and electron beam heating deposition method, shape of deposition source such as crucible and boat, degree of vacuum, deposition temperature, base temperature, deposition rate, etc. It is a parameter. In order to make uniform deposition possible, it is preferable to perform deposition by rotating the substrate. The degree of vacuum is preferably higher, and vacuum deposition is performed at 10 ⁻⁴ Torr or less, preferably 10 ⁻⁶ Torr or less, particularly preferably 10 ⁻⁸ Torr or less. It is preferable that all steps during the vapor deposition are performed in a vacuum, and basically the compound is not directly in contact with oxygen and moisture in the outside air. The above-described conditions for vacuum deposition need to be strictly controlled because they affect the crystallinity, amorphousness, density, density, etc. of the organic film. It is preferable to use PI or PID control of the deposition rate using a film thickness monitor such as a quartz crystal resonator or an interferometer. When two or more kinds of compounds are vapor-deposited simultaneously, a co-evaporation method, a flash vapor deposition method, or the like can be preferably used.

  As described above, the undercoat film 121 is for suppressing a DC short circuit and an increase in leakage current due to the unevenness of the surface of the lower electrode 11.

  The electron blocking film 122 is provided in order to reduce dark current due to injection of electrons from the lower electrode 11, and blocks injection of electrons from the lower electrode 11 into the photoelectric conversion film 12. The charge blocking film 122 can also be used as the undercoat film 121.

  The hole blocking film 124 is provided in order to reduce dark current due to injection of holes from the upper electrode 13, and prevents holes from the upper electrode 13 from being injected into the photoelectric conversion film 12. To do.

  The hole blocking / buffer film 125 has the function of the hole blocking film 124 and the function of reducing damage to the photoelectric conversion film 12 when the upper electrode 13 is formed. When the upper electrode 13 is formed on the photoelectric conversion film 12, high energy particles existing in the apparatus used for forming the upper electrode 13, for example, sputtering, sputter particles, secondary electrons, Ar particles, oxygen When negative ions or the like collide with the photoelectric conversion film 12, the photoelectric conversion film 12 may be altered and performance degradation may occur, such as an increase in leakage current or a decrease in sensitivity. As one method for preventing this, it is preferable to provide the buffer film 125 on the photoelectric conversion film 12.

  The material of the hole blocking / buffer film 125 is preferably an organic substance such as copper phthalocyanine, PTCDA, acetylacetonate complex, or BCP, an organic-metal compound, or an inorganic substance such as MgAg or MgO. Further, the hole blocking and buffer film 125 preferably has a high visible light transmittance so as not to prevent light absorption of the photoelectric conversion film 12, and a material that does not absorb in the visible region is selected. It is preferable to use an extremely thin film thickness. The film thickness of the hole blocking / buffer film 125 varies depending on the structure of the photoelectric conversion film 12, the film thickness of the upper electrode 13, and the like, but it is particularly preferable to use a film thickness of 2 to 50 nm.

The work function adjustment film 126 is for adjusting the work function of the upper electrode 13 and suppressing dark current. When the upper electrode 13 is made of a material having a relatively large work function (for example, 4.5 eV or more) (for example, any one of ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , and FTO), the work function is adjusted. As a material of the film 126, a dark current can be effectively suppressed by using a material containing a metal having a work function of 4.5 eV or less (for example, In). The description of the advantages and the like by providing such a work function adjusting film 126 will be described later.

  The lower electrode 11 is selected in consideration of adhesion to an adjacent film, electron affinity, ionization potential, stability, and the like in order to take out holes from the photoelectric conversion film 12 and collect them. Since the upper electrode 13 takes out electrons from the photoelectric conversion film 12 and discharges the electrons, the upper electrode 13 is selected in consideration of adhesion to an adjacent film, electron affinity, ionization potential, stability, and the like.

  Various methods are used for producing the electrode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.), a coating of a dispersion of indium tin oxide, etc. A film is formed by this method. In the case of ITO, UV-ozone treatment, plasma treatment, etc. can be performed.

  The conditions for forming a transparent electrode film (transparent electrode film) will be described. The silicon substrate temperature at the time of forming the transparent electrode film is preferably 500 ° C. or lower, more preferably 300 ° C. or lower, further preferably 200 ° C. or lower, and further preferably 150 ° C. or lower. Further, a gas may be introduced during the formation of the transparent electrode film, and basically the gas species is not limited, but Ar, He, oxygen, nitrogen and the like can be used. Further, a mixed gas of these gases may be used. In particular, in the case of an oxide material, oxygen defects are often introduced, so that oxygen is preferably used.

  Further, the preferred range of the surface resistance of the transparent electrode film varies depending on whether it is the lower electrode 11 or the upper electrode 13. When the signal readout part has a CMOS structure, the surface resistance of the transparent conductive film is preferably 10000Ω / □ or less, more preferably 1000Ω / □ or less. If the signal reading unit has a CCD structure, the surface resistance is preferably 1000Ω / □ or less, and more preferably 100Ω / □ or less. When used for the upper electrode 13, it is preferably 1000000 Ω / □ or less, more preferably 100000 Ω / □ or less.

  The upper electrode 13 is preferably made plasma-free. By creating the upper electrode 13 in a plasma-free manner, the influence of plasma on the substrate can be reduced, and the photoelectric conversion characteristics can be improved. Here, plasma free means that no plasma is generated during the deposition of the upper electrode 13 or that the distance from the plasma generation source to the substrate is 2 cm or more, preferably 10 cm or more, more preferably 20 cm or more. It means a state in which the plasma that reaches is reduced.

  Examples of an apparatus that does not generate plasma during the formation of the upper electrode 13 include an electron beam vapor deposition apparatus (EB vapor deposition apparatus) and a pulse laser vapor deposition apparatus. Regarding EB deposition equipment or pulse laser deposition equipment, “Surveillance of Transparent Conductive Films” supervised by Yutaka Sawada (published by CMC, 1999); ), "Transparent conductive film technology" by the Japan Society for the Promotion of Science (Ohm Co., 1999), and the references attached thereto, etc. can be used. Hereinafter, a method of forming a transparent electrode film using an EB vapor deposition apparatus is referred to as an EB vapor deposition method, and a method of forming a transparent electrode film using a pulse laser vapor deposition apparatus is referred to as a pulse laser vapor deposition method.

  For an apparatus that can realize a state in which the distance from the plasma generation source to the substrate is 2 cm or more and the arrival of plasma to the substrate is reduced (hereinafter referred to as a plasma-free film forming apparatus), for example, an opposed target sputtering Equipment, arc plasma deposition, etc. are considered, and these are supervised by Yutaka Sawada "New development of transparent conductive film" (published by CMC, 1999), and supervised by Yutaka Sawada "New development of transparent conductive film II" (published by CMC) 2002), “Transparent conductive film technology” (Ohm Co., 1999) by the Japan Society for the Promotion of Science, and references and the like attached thereto can be used.

  The material of the transparent electrode film is preferably one that can be formed by a plasma-free film forming apparatus, an EB vapor deposition apparatus, and a pulse laser vapor deposition apparatus. For example, a metal, an alloy, a metal oxide, a metal nitride, a metal boride, an organic conductive compound, a mixture thereof, and the like are preferable. Specific examples include tin oxide, zinc oxide, indium oxide, and indium zinc oxide. (IZO), indium tin oxide (ITO), conductive metal oxides such as indium tungsten oxide (IWO), metal nitrides such as titanium nitride, metals such as gold, platinum, silver, chromium, nickel, aluminum, and these A mixture or laminate of a metal and a conductive metal oxide, an inorganic conductive material such as copper iodide or copper sulfide, an organic conductive material such as polyaniline, polythiophene or polypyrrole, a laminate of these and ITO, Etc. Also, supervised by Yutaka Sawada “New Development of Transparent Conductive Film” (published by CMC, 1999), supervised by Yutaka Sawada “New Development of Transparent Conductive Film II” (published by CMC, 2002), “Transparency by Japan Society for the Promotion of Science” Those described in detail in “Technology of Conductive Film” (Ohm Co., 1999) may be used.

Next, advantages of providing the work function adjusting film 126 will be described.
When the upper electrode 13 is made of a material having high work function such as ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , and FTO and having high transparency, the dark current when the bias is applied to the upper electrode 13 is 1 V At the time of application, it becomes considerably large as about 10 μA / cm ² . As one of the causes of the dark current, a current flowing from the upper electrode 13 to the photoelectric conversion film 12 when a bias is applied can be considered. When a highly transparent electrode such as ITO, IZO, ZnO ₂ , SnO ₂ , TiO ₂ , or FTO is used as the upper electrode 13, its work function is relatively large (4.5 eV or more), so that It was thought that the barrier when moving to the photoelectric conversion film 12 was lowered, and hole injection into the photoelectric conversion film 12 was likely to occur. Actually, when examining the work function of a highly transparent metal oxide based transparent electrode such as ITO, IZO, SnO ₂ , TiO ₂ , and FTO, for example, the work function of the ITO electrode is about 4.8 eV. The work function of the (aluminum) electrode is considerably higher than that of about 4.3 eV, and other metal oxide-based transparent electrodes other than ITO also have the smallest AZO (Al-doped zinc oxide). Except for about 4.5 eV, it is known that its work function is relatively large, about 4.6 to 5.4 (for example, J. Vac. Sci. Technol. A17 (4), Jul. / See Fig. 12 of Aug 1999 p. 1765-1772).

  When the work function of the upper electrode 13 is relatively large (4.8 eV), the barrier when holes move to the photoelectric conversion film 12 when a bias is applied is lowered, and holes from the upper electrode 13 to the photoelectric conversion film 12 are reduced. Implantation is likely to occur, and as a result, the dark current is considered to increase. In this embodiment, since the hole blocking film 124 is provided, dark current is suppressed. However, if the work function of the upper electrode 13 is large, it is difficult to suppress dark current even if the hole blocking film 124 is present. .

  Therefore, in this embodiment, a film having a work function of 4.5 eV or less is provided between the upper electrode 13 and the photoelectric conversion film 12.

  In the following, metals having a work function of 4.5 eV or less are listed together with their characteristics.

(Third embodiment of photoelectric conversion element)
In the present embodiment, a configuration in which a solid-state imaging device is realized using the photoelectric conversion device having the configuration shown in FIG.
FIG. 4 is a partial surface schematic diagram of an image sensor for explaining an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view taken along the line AA of the image sensor shown in FIG. In FIG. 4, the microlens 14 is not shown. In FIG. 5, the same reference numerals are given to the same components as those in FIG.

  A p-well layer 2 is formed on the n-type silicon substrate 1. Hereinafter, the n-type silicon substrate 1 and the p-well layer 2 are collectively referred to as a semiconductor substrate. A color filter 13r that mainly transmits R light, a color filter 13g that mainly transmits G light, and a color filter that mainly transmits B light in a row direction on the same plane above the semiconductor substrate and in a column direction perpendicular thereto. A number of three types of color filters 13b are arranged.

  A known material can be used for the color filter 13r, but such a material transmits part of infrared light in addition to R light. A known material can be used for the color filter 13g, but such a material transmits part of infrared light in addition to G light. A known material can be used for the color filter 13b, but such a material transmits part of infrared light in addition to B light.

  As the arrangement of the color filters 13r, 13g, 13b, a color filter arrangement (Bayer arrangement, vertical stripe, horizontal stripe, etc.) used in a known single-plate solid-state imaging device can be adopted.

  In the p well layer 2 below the color filter 13r, an n-type impurity region (hereinafter referred to as n region) 3r is formed corresponding to the color filter 13r, and a pn junction between the n region 3r and the p well layer 2 is formed. Thus, an R photoelectric conversion element (corresponding to the photoelectric conversion unit C in FIG. 2B) corresponding to the color filter 13r is configured.

  An n region 3g is formed in the p well layer 2 below the color filter 13g so as to correspond to the color filter 13g, and the G region corresponding to the color filter 13g is formed by a pn junction between the n region 3g and the p well layer 2. A photoelectric conversion element (corresponding to the photoelectric conversion unit C in FIG. 2B) is configured.

  An n region 3b is formed in the p well layer 2 below the color filter 13b so as to correspond to the color filter 13b, and B corresponding to the color filter 13b is formed by a pn junction between the n region 3b and the p well layer 2. A photoelectric conversion element (corresponding to the photoelectric conversion unit C in FIG. 2B) is configured.

  A transparent electrode 11r is formed above the n region 3r, a transparent electrode 11g is formed above the n region 3g, and a transparent electrode 11b is formed above the n region 3b. The transparent electrodes 11r, 11g, and 11b are divided corresponding to the color filters 13r, 13g, and 13b, respectively. The transparent electrodes 11r, 11g, and 11b have the same functions as the lower electrode 11 in FIG.

  On each of the transparent electrodes 11r, 11g, and 11b, a photoelectric conversion film 12 having a single configuration common to each of the color filters 13r, 13g, and 13b is formed.

  On the photoelectric conversion film 12, an upper electrode 13 having a single configuration common to each of the color filters 13r, 13g, and 13b is formed.

  A photoelectric conversion element corresponding to the color filter 13r (corresponding to the photoelectric conversion portion A in FIG. 2B) is formed by the transparent electrode 11r, the upper electrode 13 opposed to the transparent electrode 11r, and a part of the photoelectric conversion film 12 sandwiched therebetween. Is formed. Hereinafter, since this photoelectric conversion element is formed on a semiconductor substrate, it is referred to as an R-substrate photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 13g (corresponding to the photoelectric conversion part A in FIG. 2B) is formed by the transparent electrode 11g, the upper electrode 13 opposed to the transparent electrode 11g, and a part of the photoelectric conversion film 12 sandwiched therebetween. Is formed. Hereinafter, this photoelectric conversion element is referred to as a G-substrate photoelectric conversion element.

  A photoelectric conversion element corresponding to the color filter 13b (corresponding to the photoelectric conversion portion A in FIG. 2B) is formed by the transparent electrode 11b, the upper electrode 13 facing the transparent electrode 11b, and a part of the photoelectric conversion film 12 sandwiched therebetween. Is formed. Hereinafter, this photoelectric conversion element is referred to as a B-substrate photoelectric conversion element.

  Next to the n region 3r in the p-well layer 2 is a high-concentration n-type impurity region (hereinafter referred to as an n + region) 4r for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the R substrate. Is formed. In order to prevent light from entering the n + region 4r, it is preferable to provide a light shielding film on the n + region 4r.

  Next to the n region 3g in the p-well layer 2, an n + region 4g for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the G substrate is formed. In order to prevent light from entering the n + region 4g, it is preferable to provide a light shielding film on the n + region 4g.

  Next to the n region 3b in the p well layer 2, an n + region 4b for accumulating charges generated in the photoelectric conversion film 12 of the photoelectric conversion element on the B substrate is formed. In order to prevent light from entering the n + region 4b, it is preferable to provide a light shielding film on the n + region 4b.

  A contact portion 6r made of a metal such as aluminum is formed on the n + region 4r, and a transparent electrode 11r is formed on the contact portion 6r. The n + region 4r and the transparent electrode 11r are electrically connected by the contact portion 6r. ing. The contact portion 6r is embedded in the insulating layer 5 that is transparent to visible light and infrared light.

  A contact portion 6g made of a metal such as aluminum is formed on the n + region 4g, and a transparent electrode 11g is formed on the contact portion 6g. The n + region 4g and the transparent electrode 11g are electrically connected by the contact portion 6g. ing. The contact portion 6g is embedded in the insulating layer 5.

  A contact portion 6b made of a metal such as aluminum is formed on the n + region 4b, and a transparent electrode 11b is formed on the contact portion 6b. The n + region 4b and the transparent electrode 11b are electrically connected by the contact portion 6b. ing. The contact portion 6 b is embedded in the insulating layer 5.

  In regions other than where the n regions 3r, 3g, 3b and n + regions 4r, 4g, 4b are formed in the p-well layer 2, depending on the charges generated in the R photoelectric conversion element and accumulated in the n region 3r. A signal reading unit 5r for reading out the corresponding signal and a signal corresponding to the charge accumulated in the n + region 4r, and a signal corresponding to the charge generated in the G photoelectric conversion element and accumulated in the n region 3g and the n + region 4g. A signal reading unit 5g for reading a signal corresponding to the charge accumulated in the signal, a signal corresponding to the charge generated in the B photoelectric conversion element and accumulated in the n region 3b, and a charge accumulated in the n + region 4b. A signal reading unit 5b for reading the corresponding signals is formed. Each of the signal reading units 5r, 5g, and 5b can adopt a known configuration using a CCD or a MOS circuit. In order to prevent light from entering the signal readout units 5r, 5g, 5b, it is preferable to provide a light shielding film on the signal readout units 5r, 5g, 5b.

  FIG. 6 is a diagram illustrating a specific configuration example of the signal reading unit 5r illustrated in FIG. In FIG. 6, the same components as those in FIGS. Note that the signal readout units 5r, 5g, and 5b have the same configuration, and thus the description of the signal readout units 5g and 5b is omitted.

  The signal readout section 5r has a reset transistor 43 whose drain is connected to the n + region 4r, its source connected to the power supply Vn, and an output transistor 42 whose gate is connected to the drain of the reset transistor 43 and whose source is connected to the power supply Vcc. A row selection transistor 41 whose source is connected to the drain of the output transistor 42 and whose drain is connected to the signal output line 45; a reset transistor 46 whose drain is connected to the n region 3r and whose source is connected to the power supply Vn; The output transistor 47 whose gate is connected to the drain of the reset transistor 46, the source is connected to the power supply Vcc, and the row selection transistor 48 whose source is connected to the drain of the output transistor 47 and whose drain is connected to the signal output line 49. With.

  By applying a bias voltage between the transparent electrode 11r and the upper electrode 13, a charge is generated according to the light incident on the photoelectric conversion film 12, and the charge moves to the n + region 4r through the transparent electrode 11r. The charge accumulated in the n + region 4r is converted into a signal corresponding to the amount of charge by the output transistor. Then, a signal is output to the signal output line 45 by turning on the row selection transistor 41. After the signal is output, the charge in the n + region 4r is reset by the reset transistor 43.

  The charge generated in the R photoelectric conversion element and accumulated in the n region 3r is converted into a signal corresponding to the charge amount by the output transistor 47. Then, a signal is output to the signal output line 49 by turning on the row selection transistor 48. After the signal is output, the charge in the n region 3r is reset by the reset transistor 46.

  Thus, the signal reading unit 5r can be configured by a known MOS circuit including three transistors.

  Returning to FIG. 5, two-layer protective layers 15 and 16 for protecting the photoelectric conversion element on the substrate are formed on the photoelectric conversion film 12, and color filters 13 r, 13 g, and 13 b are formed on the protective layer 16. On each of the color filters 13r, 13g, 13b, a microlens 14 for condensing light is formed on the corresponding n regions 3r, 3g, 3b.

  The image pickup device 100 is manufactured by forming the color filters 13r, 13g, 13b, the microlens 14 and the like after forming the photoelectric conversion film 12, but the color filters 13r, 13g, 13b and the microlens 14 are formed by photo When an organic material is used as the photoelectric conversion film 12 because it includes a lithography process and a baking process, the characteristics of the photoelectric conversion film 12 are deteriorated when the photolithography process and the baking process are performed with the photoelectric conversion film 12 exposed. Resulting in. In the imaging device 100, protective layers 15 and 16 are provided in order to prevent the deterioration of the characteristics of the photoelectric conversion film 12 due to such a manufacturing process.

The protective layer 15 is preferably an inorganic layer made of an inorganic material formed by the ALCVD method. The ALCVD method is an atomic layer CVD method, can form a dense inorganic layer, and can be an effective protective layer for the photoelectric conversion layer 9. The ALCVD method is also known as the ALE method or ALD method. The inorganic layer formed by the ALCVD method is preferably made of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , MgO, HfO ₂ , Ta ₂ O ₅ , more preferably made of Al ₂ O ₃ , SiO ₂ , Most preferably, it consists of Al ₂ O ₃ .

  The protective layer 16 is formed on the protective layer 15 in order to further improve the protective performance of the photoelectric conversion film 12, and is preferably an organic layer made of an organic polymer. Parylene is preferable as the organic polymer, and parylene C is more preferable. The protective layer 16 may be omitted, and the arrangement of the protective layer 15 and the protective layer 16 may be reversed. The protection effect of the photoelectric conversion film 12 is particularly high in the configuration shown in FIG.

  In the imaging device 100 having the above-described configuration, infrared light in the light transmitted through the color filter 13r out of incident light is absorbed by the photoelectric conversion film 12, and charges corresponding to the infrared light are generated here. To do. Similarly, infrared light out of the light transmitted through the color filter 13g out of the incident light is absorbed by the photoelectric conversion film 12, and charges corresponding to the infrared light are generated here. Similarly, infrared light out of the light transmitted through the color filter 13b out of the incident light is absorbed by the photoelectric conversion film 12, and charges corresponding to the infrared light are generated here.

  When a predetermined bias voltage is applied to the transparent electrode 11r and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the R substrate move to the n + region 4r via the transparent electrode 11r and the contact portion 6r. , Accumulated here. Then, a signal corresponding to the electric charge accumulated in the n + region 4r is read by the signal reading unit 5r and output to the outside of the image sensor 100.

  Similarly, when a predetermined bias voltage is applied to the transparent electrode 11g and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the G substrate are transferred to the n + region 4g via the transparent electrode 11g and the contact portion 6g. Go to and accumulate here. Then, a signal corresponding to the electric charge accumulated in the n + region 4g is read out by the signal reading unit 5g and output to the outside of the image sensor 100.

  Similarly, when a predetermined bias voltage is applied to the transparent electrode 11b and the upper electrode 13, charges generated in the photoelectric conversion film 12 constituting the photoelectric conversion element on the B substrate are transferred to the n + region 4b via the transparent electrode 11b and the contact portion 6b. Go to and accumulate here. Then, a signal corresponding to the electric charge accumulated in the n + region 4b is read by the signal reading unit 5b and output to the outside of the image sensor 100.

  The R light that has passed through the color filter 13r and has passed through the photoelectric conversion film 12 is incident on the R photoelectric conversion element, and charges corresponding to the amount of incident light are accumulated in the n region 3r. Similarly, the G light transmitted through the color filter 13g and transmitted through the photoelectric conversion film 12 enters the G photoelectric conversion element, and charges corresponding to the amount of incident light are accumulated in the n region 3g. Similarly, the B light transmitted through the color filter 13b and transmitted through the photoelectric conversion film 12 enters the B photoelectric conversion element, and charges corresponding to the amount of incident light are accumulated in the n region 3b. The charges accumulated in the n regions 3r, 3g, and 3b are read by the signal reading units 5r, 5g, and 5b, and are output to the outside of the image sensor 100.

  The arrangement of signals read out and output from the n regions 3r, 3g, 3b is the same as the arrangement of signals output from the single-plate color solid-state image pickup device having the color filter arrangement as shown in FIG. By performing signal processing used in the color solid-state imaging device, color image data in which data of three color components of R, G, and B is given to one pixel data can be generated. Further, infrared image data in which one pixel data has infrared color component data can be generated by signals read out and output from the n + regions 4r, 4g, and 4b.

  As described above, the image sensor 100 generates the R component signal corresponding to the charge generated in the R photoelectric conversion element, the G component signal corresponding to the charge generated in the G photoelectric conversion element, and the B photoelectric conversion element. A B component signal corresponding to the charge, an IR component signal corresponding to the charge generated in the photoelectric conversion element on the R substrate, an IR component signal corresponding to the charge generated in the photoelectric conversion element on the G substrate, and the B substrate An IR component signal corresponding to the electric charge generated in the upper photoelectric conversion element can be output to the outside. For this reason, if the image sensor 100 is used, two types of image data, that is, color image data and infrared image data, can be obtained by one imaging. Therefore, this image sensor 100 can be used as, for example, an image sensor of an endoscope apparatus that requires an appearance image of a part to be inspected of a human body and an internal image of the part.

[Synthesis of squarylium compound 3]

Synthetic intermediate 1 (1.43 g, 5.0 mmol) synthesized according to the literature (Dyes and Pigments, 21 (1993), 227-234) and 1-ethyl-2-methylquinolinium iodide (1.50 g, 5 0.0 mmol) was mixed with 1-butanol (30 mL) and toluene (30 mL) and heated to reflux for about 6 hours. After cooling to room temperature, the precipitate was filtered by suction and washed with isopropanol to obtain a green powder. This was boiled with chloroform, suction filtered and washed, further boiled with acetone, and then suction filtered and washed to obtain Compound 3 (1.6 g, yield 74%) as a green powder.
¹ H NMR (DMSO, 300 MHz) δ = 9.43 (d, 1H), 8.04 (d, 1H), 7.95 (d, 1H), 7.85 (d, 1H), 7.77 ( t, 1H), 7.50 (t, 1H), 7.42 (d, 1H), 7.28 (t, 1H), 7.17 (d, 1H), 7.04 (t, 1H), 5.90, (s, 1H), 5.53 (s, 1H), 4.54 (q, 2H), 3.43 (s, 3H), 1.66 (s, 6H), 1.43 ( t, 3H).

[Synthesis of squarylium compound 2]

A squarylium compound 2 was synthesized in the same manner as in Example 1 except that the synthetic intermediate 2 synthesized by the same method was used instead of the synthetic intermediate 1 in Example 1.
¹ H NMR (CDCl ₃ , 300 MHz) δ = 9.53 (d, 1H), 8.18 (d, 1H), 7.89-7.83 (m, 2H), 7.67-7.49 ( m, 5H), 7.40-7.32 (2H), 7.30-7.24 (m, 1H), 6.01 (s, 1H), 5.82 (s, 1H), 4.43 (Q, 2H), 3.57 (s, 3H), 2.08 (s, 6H), 1.56 (t, 3H).

[Example of photoelectric conversion element]
After forming a lower electrode by forming a film of amorphous ITO 30 nm on a silicon substrate by sputtering, a compound 1 represented by the following chemical formula is deposited on the lower electrode by 100 nm by vacuum heating vapor deposition, and then a compound represented by the following chemical formula 2 was formed into a film with a thickness of 50 nm by vacuum heating vapor deposition to form a photoelectric conversion film. Next, Alq 50 nm shown by the following chemical formula was formed on the film by vacuum heating deposition to form a hole blocking film. Next, 5 nm of amorphous ITO was formed on the hole blocking film by sputtering to form an upper electrode, thereby producing a photoelectric conversion element.

All the above vacuum heating depositions were performed at a vacuum degree of 4 × 10 ⁻⁴ Pa or less. The transmittance of the upper electrode itself in the wavelength range of 400 to 900 nm was 98% or more. The measurement result of the absorption spectrum of the photoelectric conversion part which consists of an ITO lower electrode, a photoelectric conversion film, a hole blocking film, and an ITO upper electrode is shown in FIG. At this time, there was no appearance of decomposition of the material during the vapor deposition of Compound 2, and in the above absorption spectrum, the absorption at 738 nm was a maximum, and the absorption at 450 to 600 nm was 30% or less.

  In Example 3, a photoelectric conversion element was produced in the same manner except that the compound 2 in the photoelectric conversion film was changed to the compound 3. The transmittance of the upper transparent electrode itself in the wavelength range of 400 to 900 nm was 98% or more. The measurement result of the absorption spectrum of the photoelectric conversion part which consists of an ITO lower electrode, a photoelectric conversion film, a hole blocking film, and an ITO upper electrode is shown in FIG. At this time, there was no appearance of decomposition of the material during the deposition of the compound 3, and in the above absorption spectrum, the absorption was maximum at 733 nm and the absorptance at 450 to 600 nm was 50% or less.

[Reference Example 1]
In Example 3, a photoelectric conversion element was produced in the same manner except that Compound 2 in the photoelectric conversion film was changed to Compound 4. The transmittance of the upper transparent electrode itself in the wavelength range of 400 to 900 nm was 98% or more. The measurement result of the absorption spectrum of the photoelectric conversion part which consists of an ITO lower electrode, a photoelectric conversion film, a hole blocking film, and an ITO upper electrode is shown in FIG. At this time, there was no appearance of decomposition of the material during the deposition of Compound 4, and in the above absorption spectrum, the absorption was maximum at 760 nm, and the absorptance at 450 to 600 nm was 30% or less.

[Comparative Example 1]
In Example 3, a photoelectric conversion element was produced in the same manner except that Compound 2 in the photoelectric conversion film was changed to Compound 4. The transmittance of the upper transparent electrode itself in the wavelength range of 400 to 900 nm was 98% or more. The measurement result of the absorption spectrum of the photoelectric conversion part which consists of an ITO lower electrode, a photoelectric conversion film, a hole blocking film, and an ITO upper electrode is shown in FIG. At this time, there was no appearance of decomposition of the material during the deposition of Compound 5, and in the above absorption spectrum, the absorption was maximum at 680 nm, and the absorptance at 450 to 600 nm was 30% or less.

[Comparative Example 2]
In Example 3, a photoelectric conversion element was produced in the same manner except that Compound 2 in the photoelectric conversion film was changed to Compound 6. The transmittance of the upper transparent electrode itself in the wavelength range of 400 to 900 nm was 98% or more. The measurement result of the absorption spectrum of the photoelectric conversion part which consists of an ITO lower electrode, a photoelectric conversion film, a hole blocking film, and an ITO upper electrode is shown in FIG. At this time, decomposition of the material occurred during the deposition of Compound 6. In the said absorption spectrum, it had maximum absorption in 765 nm and the absorptance of 450-600 nm was 30% or less.

The vapor deposition temperature, the decomposition temperature measured by TG-DTA in nitrogen, and the dark current of each photoelectric conversion element 3 nA / cm ^{2 for} compounds 2 to 7 in Examples 3 and 4, Reference Example 1 and Comparative Examples 1 to 3. The external quantum efficiency at the maximum sensitivity wavelength is shown in Table A. Note that, when measuring the photoelectric conversion performance of each element, an appropriate voltage was applied.

  When an unsuitable material is selected as in Comparative Example 2, the difference between the deposition temperature and the decomposition temperature becomes small, decomposition occurs during the deposition, and the photoelectric conversion efficiency is low. Moreover, in Reference Example 1 and Comparative Example 1, it is possible to obtain a vapor deposition film by increasing the difference between the decomposition temperature and the vapor deposition temperature by adding a bulky substituent or the like, and suppressing the decomposition during vapor deposition. However, the photoelectric conversion efficiency in the low dark current region is low. On the other hand, in the compounds 1 and 2 which are the squarylium compounds of the present invention, a difference between the vapor deposition temperature capable of maintaining vapor deposition and a decomposition temperature can be obtained, and high photoelectric conversion performance can be obtained in a low dark current region. According to the present invention, visible light can be detected by the PD in the substrate, and infrared light of 700 nm or more can be imaged at the same time and at the same point with high S / N by the upper photoelectric conversion unit.

Sectional schematic diagram which shows schematic structure of the photoelectric conversion element which is 1st embodiment of this invention. Sectional schematic diagram which shows schematic structure of the photoelectric conversion element which is 2nd embodiment of this invention. Cross-sectional schematic diagram showing a preferred embodiment of the photoelectric conversion element of the first embodiment The partial surface schematic diagram of the image pick-up element for describing embodiment of this invention 4 is a schematic cross-sectional view taken along the line AA of the image sensor shown in FIG. The figure which shows the specific structural example of the signal reading part shown in FIG. The figure which showed the absorption spectrum of the element of Example 3 The figure which showed the absorption spectrum of the element of Example 4 The figure which showed the absorption spectrum of the element of the reference example 1 The figure which showed the absorption spectrum of the element of the comparative example 1 The figure which showed the absorption spectrum of the element of the comparative example 2

Explanation of symbols

11 Lower electrode 12 Photoelectric conversion film 13 Upper electrode

Claims (15)

A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film includes an organic photoelectric conversion material, A photoelectric conversion element, wherein the photoelectric conversion material contains a compound represented by the following general formula (SQ-2).
General formula (SQ-2)

(Wherein R ^{1 to} R ⁸ each independently represents a hydrogen atom or a substituent. A plurality of R ^{1 to} R ⁸ may be linked to form a ring. B represents a quinoline nucleus, a pyrylium nucleus, It represents an unsubstituted methine group to which a thiopyrylium nucleus, an azulene nucleus or a dihydroperimidine nucleus is bonded, and the methine group is bonded to a carbon atom of the quinoline nucleus, pyrylium nucleus, thiopyrylium nucleus, azulene nucleus or dihydroperimidine nucleus . ) The photoelectric conversion element according to claim 1, wherein the general formula (SQ-2) is represented by the following general formula (SQ-3).
General formula (SQ-3)

(In the formula, B has the same meaning as the general formula (SQ-2).) A photoelectric conversion element including a photoelectric conversion unit including a pair of electrodes and a photoelectric conversion film provided between the pair of electrodes, wherein the photoelectric conversion film has an absorption spectrum in a range in which a visible region and an infrared region are combined. have absorption maxima in the infrared region, it is configured to include the absorbed organic photoelectric conversion material that generates charges corresponding to light, at least one general formula according to claim 1 or 2 of the organic photoelectric conversion material (SQ -2) or (SQ-3),
The photoelectric conversion device according to claim 1 or 2, wherein the pair of electrodes is characterized in that it comprises a TCO. The photoelectric conversion element according to claim 3 , wherein the TCO is ITO. The photoelectric conversion part comprises a semiconductor substrate laminated above,
A visible light photoelectric conversion unit that has an absorption maximum of an absorption spectrum in a range including a visible region and an infrared region in the visible region and generates a charge according to absorbed light is at least 1 between the semiconductor substrate and the photoelectric conversion unit. The photoelectric conversion element according to claim 3, wherein the photoelectric conversion element is provided. The semiconductor substrate includes an accumulation unit that accumulates charges generated in each of the photoelectric conversion unit and the visible light photoelectric conversion unit, and a signal reading unit that reads a signal corresponding to the charge accumulated in the accumulation unit. The photoelectric conversion element according to claim 5 . The photoelectric conversion part comprises a semiconductor substrate laminated above,
The semiconductor substrate has at least one visible light photoelectric conversion portion that has an absorption peak of an absorption spectrum in a visible region and an infrared region in the visible region and generates a charge corresponding to the absorbed light. The photoelectric conversion element according to any one of claims 3 to 6 . According to claim 7, wherein the semiconductor substrate, characterized by comprising a storage unit for storing charge generated in the photoelectric conversion unit, and a signal readout section for reading out a signal corresponding to the charges accumulated in the accumulation unit Photoelectric conversion element. A plurality of the visible light photoelectric conversion units,
The photoelectric conversion device according to claim 5 , wherein the plurality of visible light photoelectric conversion units have absorption peaks at different wavelengths. The photoelectric conversion element according to claim 9 , wherein the plurality of visible light photoelectric conversion units are stacked in a light incident direction to the photoelectric conversion unit. A plurality of the visible light photoelectric conversion units,
Wherein the plurality of visible light photoelectric conversion portion, has an absorption peak at a different wavelength respectively, and, according to claim 8, characterized in that it is arranged in a direction perpendicular to the direction of light incidence to the photoelectric conversion portion Photoelectric conversion element. Three visible light photoelectric conversion units are provided,
The three visible light photoelectric conversion units absorb an R photoelectric conversion unit that absorbs light in the red wavelength range, a G photoelectric conversion unit that absorbs light in the green wavelength range, and B that absorbs light in the blue wavelength range. It is a photoelectric conversion part, The photoelectric conversion element of Claim 10 or 11 characterized by the above-mentioned. As light transmitted through the photoelectric conversion unit is incident on the visible light photoelectric conversion unit, according to claim 1 to 12, wherein said photoelectric conversion unit visible light photoelectric conversion unit, characterized in that the overlap in a plan view The photoelectric conversion element as described in any one. The photoelectric conversion film, a hole blocking layer, and the photoelectric conversion element according to any one of claims 1 to 13, characterized in that it comprises an electron blocking layer. A solid-state imaging device comprising the photoelectric conversion device according to any one of claims 1 to 14 , wherein at least one of the photoelectric conversion portions is arranged in an array on the same plane .

Images