JP2007317565A - Organic photoelectric conversion element - Google Patents

Abstract

An organic photoelectric conversion element capable of effectively using incident light and obtaining excellent energy conversion efficiency is provided.
A transparent substrate, a transparent electrode layer, a photoelectric conversion layer, and a metal electrode layer are provided. A re-reflection layer 6 that re-reflects the light beam reflected by the metal electrode layer 5 is provided on the light receiving surface of the transparent substrate 2. The re-reflection layer 6 is formed integrally with the transparent substrate 2. The re-reflection layer 6 includes a plurality of conical protrusions 7 and 9 or a conical recess 8. The cones are regular quadrangular pyramids and the bases touch each other. The regular square pyramid has a base of 10 to 100 μm and an apex angle of 20 to 150 °. The cones are cones and overlap each other at the outer part of the square inscribed in the bottom surface. The cone has a square side inscribed in the bottom of 10 to 100 μm and an apex angle of 20 to 150 °. The re-reflection layer 6 includes an ultraviolet blocking material.
[Selection] Figure 1

Description

  The present invention relates to an organic photoelectric conversion element used as an organic solar cell, for example.

  Organic photoelectric conversion elements used as organic solar cells and the like have advantages not found in silicon devices, such as low energy costs required for manufacturing, because they can be easily enlarged by applying printing technology.

  Organic photoelectric conversion elements have been studied as organic solar cells since the latter half of the 1970s, and initially dye photoelectric conversion elements using Schottky junctions have been actively studied.

  In contrast, in 1986, C.I. W. Tang published a pn junction organic solar cell 31 shown in FIG. The pn junction type organic solar cell 31 includes a transparent electrode layer 3 formed on the surface opposite to the light receiving surface of the transparent glass substrate 2, a photoelectric conversion layer 4 formed on the transparent electrode layer 3, and a photoelectric conversion layer. The photoelectric conversion layer 4 is formed of a p-type organic semiconductor layer 32 and an n-type organic semiconductor layer 33 that are stacked in this order from the transparent electrode layer 3 side. . The pn junction organic solar cell 31 has an energy conversion efficiency of 1% (see Non-Patent Document 1).

  On the other hand, in 1991, M.M. Gretzel et al. Announced a dye-sensitized solar cell 41 shown in FIG. The dye-sensitized solar cell 41 includes a transparent electrode layer 3 formed on the surface opposite to the light receiving surface of the transparent glass substrate 2a, a photoelectric conversion layer 4 formed on the transparent electrode layer 3, and a transparent glass substrate 2b. The photoelectric conversion layer 4 is sandwiched between the transparent electrode layer 3 and the metal electrode layer 5. The photoelectric conversion layer 4 is sandwiched between the transparent electrode layer 3 and the metal electrode layer 5. The photoelectric conversion layer 4 is formed by a dye adsorption layer 42 formed on the transparent electrode layer 3 and an electrolytic solution layer 43 injected between the two glass substrates 2a and 2b. Although the dye-sensitized solar cell 41 is wet, it is said that an energy conversion efficiency of 10% is obtained (see Non-Patent Document 2).

  In recent years, a pin junction type organic solar cell 51 shown in FIG. 12 has been proposed. The pin junction type organic solar cell 51 includes a transparent electrode layer 3 formed on the surface opposite to the light receiving surface of the transparent glass substrate 2, a photoelectric conversion layer 4 formed on the transparent electrode layer 3, and a photoelectric conversion layer. 4, the photoelectric conversion layer 4 includes a p-type organic semiconductor layer 52, a p-type organic semiconductor, and an n-type organic semiconductor, which are sequentially stacked from the transparent electrode layer 3 side. A co-deposited nanostructure layer (i layer) 53, an n-type organic semiconductor layer 54, and a buffer layer 55 for improving the connectivity between the n-type organic semiconductor layer 54 and the metal electrode layer 5 are formed. According to the pin junction type organic solar cell 51, it is said that an energy conversion efficiency of 2.5 to 3.5% is obtained (see Non-Patent Documents 3 and 4).

However, in each of the conventional organic solar cells 31, 41, 51, since the photoelectric conversion layer 4 is formed of an organic thin film and is very thin, light absorption is small and incident light cannot be used effectively. There is an inconvenience. Further, if the thickness of the organic thin film is increased in order to increase the light absorption, it becomes difficult to move the charges generated by the photoelectric conversion, and the energy conversion efficiency is lowered.
CWTang, Appl.Phys.Lett., 48, 183 (1986) B.O'Regan, M.Gratzel, Nature, 353, 737 (1991) Satsuma, Chikamatsu, Hara, Yoshida, Saito, Yase, "Technical Research Report of IEICE" OME2004-90 (2004) S. Uchida, J. Xue, BPRand, SRForrest, Appl. Phys. Lett., 84, 4218 (2004)

  An object of the present invention is to provide an organic photoelectric conversion element that can eliminate such inconvenience, can effectively use incident light, and can obtain excellent energy conversion efficiency.

  In order to achieve such an object, the organic photoelectric conversion element of the present invention includes a transparent substrate having one surface as a light receiving surface, and a transparent electrode layer formed on a surface of the transparent substrate opposite to the light receiving surface. In the organic photoelectric conversion element comprising a photoelectric conversion layer having an organic dye formed on the transparent electrode and a metal electrode layer formed on the photoelectric conversion layer, the metal is formed on the light receiving surface of the transparent substrate. A re-reflection layer that re-reflects the light beam reflected by the electrode layer is provided.

  In general, in an organic photoelectric conversion element, light incident from the light receiving surface of the transparent substrate enters the photoelectric conversion layer, and a part of the light generates charges by photoelectric conversion. Thereafter, the remainder of the light beam is reflected by the metal electrode layer, reenters the photoelectric conversion layer, and a part of the light beam generates a charge by photoelectric conversion. Then, the remaining light beam that has not been subjected to photoelectric conversion travels toward the light receiving surface of the transparent substrate.

  Here, in the organic photoelectric conversion element of the present invention, since the re-reflection layer is provided on the light-receiving surface of the transparent substrate, the light emitted from the photoelectric conversion layer is reflected by the re-reflection layer, and again the photoelectric photoelectric conversion element. Incident on the conversion layer. As a result, the light incident from the light receiving surface of the transparent substrate repeats reflection at the metal electrode layer and reflection at the re-reflection layer, and is repeatedly incident on the photoelectric conversion layer.

  Therefore, according to the organic photoelectric conversion element of the present invention, it is possible to perform photoelectric conversion by effectively using the light incident from the light receiving surface of the transparent substrate, and it is excellent without increasing the film thickness of the photoelectric conversion layer. Energy conversion efficiency can be achieved.

  The re-reflection layer may be formed separately from the transparent substrate, or may be formed integrally.

  The re-reflection layer may have any shape as long as it can re-reflect the light beam reflected by the metal electrode layer to the photoelectric conversion layer side. In order to reflect well, it preferably includes a plurality of conical protrusions or conical recesses. The cones forming the cone-shaped protrusions or cone-shaped recesses are preferably regular quadrangular pyramids, for example, and their bases are preferably in contact with each other. For example, the regular quadrangular pyramid has a base length in the range of 10 to 100 μm and an apex angle in the range of 20 to 150 °, whereby the light beam can be efficiently reflected.

  The cones forming the cone-shaped projections or the cone-shaped recesses are, for example, cones, and preferably overlap each other at an outer portion of a square inscribed in the bottom surface. The cone has a length of one side of a square inscribed in the bottom surface in a range of 10 to 100 μm and an apex angle in a range of 20 to 150 °, whereby the light beam can be efficiently reflected.

  In addition, the re-reflective layer includes an ultraviolet blocking material, thereby preventing ultraviolet light from entering the light receiving surface of the transparent substrate and preventing the photoelectric conversion layer from being deteriorated by ultraviolet light.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view showing a schematic configuration of the organic photoelectric conversion element of the present embodiment, FIG. 2A is a perspective view showing a configuration example of the re-reflection layer shown in FIG. 1, and FIG. Fig. 2 (a) is a plan view of the re-reflection layer, Fig. 2 (c) is a cross-sectional view taken along the line II-II of Fig. 2 (b), and Fig. 3 (a) is a diagram of the re-reflection layer shown in Fig. 1. FIG. 3B is a plan view of the re-reflection layer shown in FIG. 3A, FIG. 3C is a cross-sectional view taken along line III-III in FIG. 4A is a partial plan view showing still another configuration example of the re-reflection layer shown in FIG. 1, and FIG. 4B is a cross-sectional view taken along line IV-IV in FIG. 4A. 5 is a histogram showing the relationship between the incident angle of light rays in the organic photoelectric conversion element shown in FIG. 1 and the amount of absorbed light in the photoelectric conversion layer, and FIG. 6 is the apex angle of the re-reflection layer shown in FIG. FIG. 7 is a graph showing the relationship between the apex angle of the re-reflection layer shown in FIG. 3, the photoelectric conversion rate, the re-emission rate, and the electrode loss rate. 8 is an explanatory cross-sectional view showing a first example of the specific configuration of the organic photoelectric conversion element shown in FIG. 1, and FIG. 9 shows a second example of the specific configuration of the organic photoelectric conversion element shown in FIG. It is explanatory sectional drawing which shows an example.

  As shown in FIG. 1, the organic photoelectric conversion element 1 of the present embodiment is formed on a transparent glass substrate 2 having one surface as a light receiving surface, and a surface of the transparent glass substrate 2 opposite to the light receiving surface. A transparent electrode layer 3, a photoelectric conversion layer 4 having an organic dye formed on the transparent electrode layer 3, and a metal electrode layer 5 formed on the photoelectric conversion layer 4 are provided. The light receiving surface of the transparent glass substrate 2 is provided with a re-reflection layer 6 that re-reflects the light beam reflected by the metal electrode layer 5.

  The transparent electrode layer 3 can be formed of, for example, ITO.

  The photoelectric conversion layer 4 may have a configuration known per se. For example, the configuration of the photoelectric conversion layer used for a pin junction type organic solar cell, a dye-sensitized solar cell, or the like can be used as it is. Here, the said organic pigment | dye contained in the photoelectric converting layer 4 is zinc phthalocyanine, copper phthalocyanine, a ruthenium complex etc., for example.

  The photoelectric conversion layer 4 used in the pin junction type organic solar cell includes a p-type organic semiconductor layer, and a nanostructure layer (i) in which a p-type organic semiconductor and an n-type organic semiconductor are co-deposited in this order from the transparent electrode layer 3 side. Layer), an n-type organic semiconductor layer, and a buffer layer. Examples of the p-type organic semiconductor include zinc phthalocyanine and copper phthalocyanine. Examples of the n-type organic semiconductor include fullerene (C60) and perylene derivatives. The nanostructure layer (i layer) can be formed by co-evaporating copper phthalocyanine and fullerene, for example, and can be formed by the buffer layer such as bathocuproine.

  On the other hand, the photoelectric conversion layer 4 used in the dye-sensitized solar cell is formed by a dye adsorption layer formed on the transparent electrode layer 3 and an electrolyte layer formed on the dye adsorption layer. . As the dye adsorbing layer, for example, titanium oxide adsorbed with a dye composed of a ruthenium complex is used. Moreover, as an electrolytic solution for forming the electrolytic solution layer, for example, an aqueous solution containing iodine ions is used.

  The metal electrode layer 5 can be formed of, for example, a metal such as MgAg co-deposited body, Pt, or Al.

  For example, as shown in FIGS. 2A and 2B, the re-reflective layer 6 includes regular quadrangular pyramidal projections 7 arranged in a lattice shape with their bases in contact with each other. Can be in the same direction as the side of the transparent glass substrate 2, for example. Since the regular quadrangular pyramidal projections 7 are in contact with each other, no plane is formed between the regular quadrangular pyramidal projections 7 and 7, so that the light beam reflected by the metal electrode layer 5 can be reliably reflected. it can.

  The length of the bottom side of the regular quadrangular pyramidal protrusion 7 can be set in the range of 10 to 100 μm, for example. Further, the apex angle θ of the regular quadrangular pyramidal projection 7 shown in FIG. 2C can be in the range of 20 to 150 °.

  In addition, the re-reflection layer 6 may be one in which regular quadrangular pyramid-shaped concave portions 8 are arranged in a lattice shape with their bases in contact with each other as shown in FIGS. 3A and 3B, for example. The regular quadrangular pyramid-shaped concave portion 8 corresponds to a shape in which the apex of the regular quadrangular pyramid having the same shape as the regular quadrangular pyramidal projection 7 shown in FIG. 2 is recessed toward the re-reflection layer 6 and the regular quadrangular pyramid is removed.

  In this case, since the regular quadrangular pyramid-shaped recesses 8 are in contact with each other in the same manner as the regular quadrangular pyramidal projections 7 shown in FIG. 2, no plane is formed between the regular quadrangular pyramidal recesses 8, 8. The light beam reflected by the metal electrode layer 5 can be reliably reflected.

  The regular quadrangular pyramid-shaped recess 8 can be arranged in the same direction as the side of the transparent glass substrate 2, for example, like the regular quadrangular pyramidal projection 7 shown in FIG. It can be in the range of 100 μm. Further, the apex angle θ of the regular quadrangular pyramidal recess 8 shown in FIG. 3C can be in the range of 20 to 150 °.

  Furthermore, the re-reflection layer 6 may be one in which, for example, conical protrusions 9 are arranged in a lattice pattern as shown in FIG. At this time, it is preferable that the conical protrusions 9 overlap each other at a portion outside the square 9b inscribed in the bottom surface 9a indicated by a virtual line. By doing in this way, since a plane is not formed between the conical protrusions 9 and 9, the light beam reflected by the metal electrode layer 5 can be reliably reflected.

  As in the case of the regular quadrangular pyramid projection 7 shown in FIG. 2, the conical projection 9 can have the arrangement direction of the inscribed squares 9 b in the same direction as the side of the transparent glass substrate 2, for example. For example, it can be set as the range of 10-100 micrometers. Further, the apex angle θ of the conical protrusion 9 shown in FIG. 4B can be in the range of 20 to 150 °.

  Although not shown, the re-reflection layer 6 has a conical recess corresponding to a shape in which the apex of the cone having the same shape as the conical protrusion 9 shown in FIG. 4 is recessed toward the re-reflection layer 6 and the cone is removed. May be provided.

  The re-reflection layer 6 is, for example, a regular quadrangular pyramidal projection 7, a regular quadrangular pyramidal recess 8, a conical projection 9, and a mold (stamper) in which the conical concave portions are arranged as described above, a UV curable resin, or the like. It can be formed by injecting. In this case, the height of the protrusion or the depth of the recess is preferably about 100 μm in consideration of molding processability.

  The re-reflection layer 6 may be formed separately from the transparent glass substrate 2 or may be formed integrally. Further, the re-reflection layer 6 may contain an ultraviolet blocking agent.

  According to the organic photoelectric conversion element 1 of the present embodiment having the above-described configuration, when a light beam is incident from the re-reflection layer 6 side of the transparent glass substrate 2, the light beam is incident on the photoelectric conversion layer 4, and a part of the light beam is photoelectric. Electric charges are generated by the conversion. Thereafter, the remainder of the light beam is reflected by the metal electrode layer 5 and re-enters the photoelectric conversion layer 4, and a part of the light beam generates a charge by photoelectric conversion. Then, the remaining light beam that has not been subjected to photoelectric conversion travels toward the light receiving surface of the transparent glass substrate 2.

  Here, since the light-receiving surface of the transparent glass substrate 2 is provided with the re-reflection layer 6, the light emitted from the photoelectric conversion layer 4 is re-reflected by the re-reflection layer 6 and enters the photoelectric conversion layer 4 again. . As a result, the light incident from the light receiving surface of the transparent glass substrate 2 repeats the reflection at the metal electrode layer 5 and the re-reflection at the re-reflection layer 6 and is incident on the photoelectric conversion layer 4 repeatedly. The charge generated by photoelectric conversion in the photoelectric conversion layer 4 can be taken out as a current by connecting the transparent electrode layer 3 and the metal electrode layer 5.

  Therefore, according to the organic photoelectric conversion element 1, photoelectric conversion can be performed by effectively using the light incident from the light receiving surface of the transparent glass substrate 2, and excellent energy conversion efficiency can be achieved.

  Next, in the case of using the organic photoelectric conversion element 1 shown in FIG. 1 having the regular tetragonal pyramidal projections 7 shown in FIG. 2 as the rereflective layer 6 (Example) and when the rereflective layer 6 is not used. In (Comparative Example), the amount of light absorbed in the photoelectric conversion layer 4 when the incident angle of the light incident from the light receiving surface of the transparent glass substrate 2 was changed was compared. The organic photoelectric conversion element 1 includes a transparent glass substrate 2, a transparent electrode layer 3 made of ITO, an organic layer, and a metal electrode layer 5 made of Al, and a photoelectric conversion layer 4 having a transmittance of 55% is placed in the middle of the organic layer. The element size used was 10 mm × 10 mm. Further, the regular quadrangular pyramidal projections 7 of the re-reflection layer 6 have a base length of 0.05 mm, a vertex angle of 90 °, and a height of 0.025 mm.

  The result is shown in FIG. 5 as the ratio of the absorbed light quantity when the incident angle of light incident from the light receiving surface of the transparent glass substrate 2 is 0 ° without using the re-reflective layer 6 and the ratio to the absorbed light quantity.

  From FIG. 5, when the re-reflective layer 6 is used (Example), the amount of absorbed light is increased compared to the case where the re-reflective layer 6 is not used (Comparative Example) regardless of the incident angle. It is clear that there is an effect of confining in the photoelectric conversion element 1 and repeatedly entering the photoelectric conversion layer 4.

  Next, in the re-reflection layer 6 shown in FIG. 2, the result of simulating the photoelectric conversion rate, the re-emitted light rate, and the electrode loss rate when the apex angle θ of the regular quadrangular pyramidal projections 7 is changed is shown in FIG. Moreover, in the re-reflection layer 6 shown in FIG. 3, the result of having simulated the photoelectric conversion rate, the re-emitted light rate, and the electrode loss rate when changing the apex angle θ of the regular quadrangular pyramidal recess 8 is shown in FIG.

  From FIG. 6, in the re-reflection layer 6 including the regular quadrangular pyramidal projections 7, the smaller the apex angle, the lower the light exit rate, and the light beam is confined in the organic photoelectric conversion element 1 and reaches the metal electrode layer 5 again. As a result, it is clear that the photoelectric conversion rate is increased. Further, from FIG. 6, it is clear that the apex angle size θ is effective in the range of 20 to 150 ° in order to confine the light beam in the organic photoelectric conversion element 1 and repeatedly enter the photoelectric conversion layer 4. .

  Moreover, it is clear from FIG. 7 that the same result as in the case of the rereflective layer 6 including the regular quadrangular pyramidal protrusions 7 (FIG. 6) is obtained in the rereflective layer 6 including the regular quadrangular pyramidal recesses 8, It is clear that the effect of causing the light to be confined in the organic photoelectric conversion element 1 and repeatedly incident on the photoelectric conversion layer 4 also by the re-reflection layer 6 having the regular quadrangular pyramid-shaped recess 8.

  Next, the 1st example of the specific structure of the organic photoelectric conversion element 1 shown in FIG. 1 is shown in FIG.

  The organic photoelectric conversion element 11 shown in FIG. 8A has a transparent electrode layer 3 made of ITO formed in a predetermined pattern on the surface opposite to the light receiving surface of the transparent glass substrate 2, and the transparent electrode layer 3. The formed photoelectric conversion layer 4 and a metal electrode layer 5 made of Al formed on the photoelectric conversion layer 4 are provided, and a part of the metal electrode layer 5 is also formed on the transparent glass substrate 2. In order to re-reflect the light beam reflected by the metal electrode layer 5, a re-reflection layer 6 having regular quadrangular pyramidal projections 7 shown in FIG. 2 is attached to the light receiving surface of the transparent glass substrate 2.

  The organic photoelectric conversion element 11 includes a stainless steel lid body 12 having a recess that accommodates the photoelectric conversion layer 4 and the metal electrode layer 5, and the lid body 12 is formed by an epoxy resin layer 13 disposed on the peripheral edge. The surface of the transparent glass substrate 2 on which the photoelectric conversion layer 4 and the metal electrode layer 5 are provided is sealed. A part of the transparent electrode layer 3 and a part of the metal electrode layer 5 are exposed to the outside of the lid 12 as extraction electrodes. Further, the lid 12 includes a getter material 14 made of a Gore-Tex (registered trademark) desiccant on the inner surface side of the recess.

  In the organic photoelectric conversion element 11, the photoelectric conversion layer 4 includes a p-type organic semiconductor layer 15 made of copper phthalocyanine, copper phthalocyanine and fullerene in order from the transparent electrode layer 3 side, as shown in an enlarged view in FIG. Are formed by laminating a nanostructure layer (i layer) 16, an n-type organic semiconductor layer 17 made of fullerene, and a buffer layer 18 made of bathocuproine, and a metal electrode layer 5 is formed on the buffer layer 18. Has been.

  The organic photoelectric conversion element 11 was manufactured as follows.

  First, the transparent glass substrate 2 with ITO was subjected to photolithography to form a transparent electrode layer 3 made of ITO and having a predetermined electrode pattern. Next, the transparent glass substrate 2 on which the transparent electrode layer 3 was formed was washed. In the cleaning, ultrasonic cleaning is performed in a neutral detergent for 10 minutes, and then ultrasonic cleaning with pure water is performed three times for rinsing, and then further isopropyl alcohol is used for dehydration and degreasing. Ultrasonic cleaning for 10 minutes and ultrasonic cleaning for 10 minutes with acetone were performed. After the cleaning, the transparent glass substrate 2 was carefully lifted out of acetone so as not to leave a watermark, dried with a nitrogen stream, and then subjected to ultraviolet ozone cleaning for 30 minutes.

Next, the cleaned transparent glass substrate 2 is placed on a substrate holder, introduced into a vacuum chamber in which an organic tank and an electrode tank are connected, and the vacuum chamber is evacuated to form a transparent electrode layer 3 on the transparent electrode layer 3. A photoelectric conversion layer 4 was formed. The photoelectric conversion layer 4 is formed by evacuating the organic tank to a pressure of 1 × 10 ⁻⁵ Pa, placing a stainless steel (SUS430) deposition mask on the transparent electrode layer 3, and depositing each organic material. It was. The vapor deposition rate of each organic substance was monitored with a crystal resonator and a crystal oscillation type film formation controller (manufactured by ULVAC, Inc., trade name: CRTM-9000), and was set to 1 to 2 angstroms / second.

  The organic materials are vapor-deposited by first depositing copper phthalocyanine to form a p-type organic semiconductor layer 15 having a thickness of 20 nm, and then co-depositing copper phthalocyanine and fullerene at a deposition rate of 1 angstrom / second. A nano-structure layer (i layer) 16 having a thickness of 10 nm was formed. Next, fullerene was vapor-deposited to form an n-type organic semiconductor layer 17 having a thickness of 30 nm, and finally bathocuproine was vapor-deposited to form a buffer layer 18 having a thickness of 10 nm.

  After the vapor deposition of each organic material, the transparent glass substrate 2 on which the photoelectric conversion layer 4 was formed on the transparent electrode layer 3 was moved to the electrode tank while maintaining the vacuum. And the vapor deposition mask corresponding to a predetermined electrode pattern was arrange | positioned on the photoelectric converting layer 4, and Al was vapor-deposited by resistance heating, and the 100-nm-thick metal electrode layer 5 was formed on the photoelectric converting layer 4. FIG.

  Next, the transparent glass substrate 2 having the metal electrode layer 5 formed on the photoelectric conversion layer 4 was introduced into a glove box under a nitrogen atmosphere without being exposed to the air, and sealed with a stainless steel lid 12. . The lid 12 is subjected to ultrasonic cleaning with isopropyl alcohol for 10 minutes and ultrasonic cleaning with acetone for 10 minutes for degreasing, and further subjected to ultraviolet ozone cleaning for 30 minutes and then introduced into the glove box. did. Sealing with the lid 12 is performed by applying an epoxy resin (manufactured by Nagase Chemtex Co., Ltd.) along the peripheral edge of the lid 12 after applying the desiccant 14 to the inner surface of the concave portion of the lid 12. Then, the lid body 12 was brought into close contact with the transparent glass substrate 2, and the epoxy resin was irradiated with ultraviolet rays for 180 seconds to be cured to form an epoxy resin layer 13.

  Next, by injecting a UV curable resin into a mold (stamper) having a shape corresponding to the re-reflection layer 6 having the regular quadrangular pyramidal projections 7 shown in FIG. 2, the base has a length of 100 μm and an apex angle. The re-reflective layer 6 including the regular quadrangular pyramidal protrusions 7 having a 90 ° height of 0.05 mm was formed. And the re-reflection layer 6 was stuck on the surface on the opposite side to the cover body 12 of the transparent glass substrate 2 sealed with the said cover body 12, and the organic photoelectric conversion element 11 was obtained.

The organic photoelectric conversion element 11 was irradiated with discharge lamp light having an energy of 26.6 mW / m ² , and current-voltage characteristics were measured. When the energy conversion efficiency of the organic photoelectric conversion element 11 was calculated from the obtained current-voltage characteristics, it was 0.81%.

  On the other hand, when the energy conversion efficiency was calculated in exactly the same manner as when the re-reflection layer 6 was applied except that the re-reflection layer 6 was not attached to the transparent glass substrate 2 sealed with the lid 12, 0.71% Met.

  Next, a second example of a specific configuration of the organic photoelectric conversion element 1 shown in FIG. 1 is shown in FIG.

  The organic photoelectric element 21 shown in FIG. 9 includes a transparent electrode layer 3 made of ITO formed in a predetermined pattern on the surface opposite to the light receiving surface of the transparent glass substrate 2, and Pt disposed opposite to the transparent electrode layer 3. A photoelectric conversion layer 4 is provided between the metal electrode layer 5 made of a thin film. The metal electrode layer 5 is formed in a predetermined pattern on the transparent electrode layer 23 made of ITO formed on one surface of the transparent glass substrate 22. Note that the transparent electrode layer 3 and the metal electrode layer 5 are arranged to face each other while being shifted from each other by the amount corresponding to the extraction electrode.

  The photoelectric conversion layer 4 is formed of a dye adsorption layer 24 formed on the transparent electrode layer 3 and an electrolyte layer 25 disposed between the metal electrode layer 5 and the dye adsorption layer 24. The dye adsorption layer 24 is composed of nano-sized titanium oxide particles on which a ruthenium complex is adsorbed as a sensitizing dye. The electrolyte solution layer 25 is made of an aqueous solution containing iodine ions injected into a space formed by sealing the periphery between the transparent glass substrates 2 and 22 with the epoxy resin layer 25.

  And in order to re-reflect the light ray reflected by the metal electrode layer 5, the re-reflection layer 6 provided with the regular pyramid-shaped protrusion 7 shown in FIG.

  The organic photoelectric conversion element 21 was manufactured as follows.

  First, the transparent glass substrate 2 with ITO was subjected to photolithography to form a transparent electrode layer 3 made of ITO and having a predetermined electrode pattern. Next, the transparent glass substrate 2 on which the transparent electrode layer 3 was formed was washed. In the cleaning, ultrasonic cleaning is performed in a neutral detergent for 10 minutes, and then ultrasonic cleaning with pure water is performed three times for rinsing, and then further isopropyl alcohol is used for dehydration and degreasing. Ultrasonic cleaning for 10 minutes and ultrasonic cleaning for 10 minutes with acetone were performed. After the cleaning, the transparent glass substrate 2 was carefully lifted out of acetone so as not to leave a watermark, dried by a nitrogen stream, and then subjected to ultraviolet ozone cleaning for 30 minutes.

  Next, a mending tape (manufactured by 3M) is applied to both ends of the surface of the transparent glass substrate 2 after the washing to form a spacer, and a titanium oxide paste containing nano-sized titanium oxide particles between the tapes (manufactured by Solaronix, Product name: Ti-Nanoxide) was dropped and applied uniformly by a squeegee method using a glass rod. Next, the transparent glass substrate 2 coated with the titanium oxide paste was held on a hot plate at 50 ° C. for 5 minutes to dry the titanium oxide paste. After the drying, the mending tape was peeled off, the transparent glass substrate 2 was held on a hot plate at 450 ° C. for 30 minutes, and the titanium oxide paste was baked. Next, the transparent glass substrate 2 was gradually cooled, and when the temperature reached about 80 ° C., it was immersed in an ethanol solution of a ruthenium complex as a sensitizing dye and held for 12 hours. After the immersion, the transparent glass substrate 2 was dried to form the dye adsorption layer 24.

  Next, a Pt thin film having a thickness of 1000 angstroms was formed on the transparent electrode layer 23 made of ITO of the transparent glass substrate 22 with ITO by a sputtering method, and the metal electrode layer 5 made of the Pt thin film was formed. Next, the surface of the transparent glass substrate 2 on which the transparent electrode layer 3 is formed and the surface of the transparent glass substrate 22 on which the metal electrode layer 5 is formed are opposed to each other, and between the dye adsorbing layer 24 and the metal electrode layer 5. The transparent glass substrates 2 and 22 were overlapped with a polymer film having a thickness of 50 μm interposed therebetween. The transparent electrode layer 3 and the metal electrode layer 5 were arranged so as to be shifted from each other by the amount corresponding to the extraction electrode. Next, an epoxy resin is applied and cured around the laminated transparent glass substrates 2 and 22 to form an epoxy resin layer 25, and the periphery is sealed with the epoxy resin layer 25 between the transparent glass substrates 2 and 22. Formed a space. Then, an electrolytic solution layer 26 was formed by injecting an aqueous solution containing iodine ions as an electrolytic solution into the space.

  Next, the re-reflective layer 6 formed in the same manner as the re-reflective layer 6 shown in FIG. 8A is stuck on the surface of the transparent glass substrate 2 opposite to the transparent electrode layer 3, and the organic photoelectric conversion element 21. Got.

The organic photoelectric conversion element 21 was irradiated with discharge lamp light having an energy of 26.6 mW / m ² , and current-voltage characteristics were measured. It was 1.6% when the energy conversion efficiency of the organic photoelectric conversion element 21 was computed from the obtained electric current-voltage characteristic.

  On the other hand, when the energy conversion efficiency was calculated in exactly the same manner as when the re-reflection layer 6 was applied except that the re-reflection layer 6 was not attached to the transparent glass substrate 2, it was 1.5%.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory sectional drawing which shows schematic structure of the organic photoelectric conversion element of this invention. (A) is a perspective view which shows one structural example of the re-reflection layer shown in FIG. 1, (b) is a top view of the re-reflection layer shown in (a), (c) is the II-II sectional view taken on the line of (b). . (A) is a perspective view which shows the other structural example of the re-reflection layer shown in FIG. 1, (b) is a top view of the re-reflection layer shown in (a), (c) is the III-III line cross section of (b). Figure. (A) is a partial top view which shows the further another structural example of the re-reflection layer shown in FIG. 1, (b) is the IV-IV sectional view taken on the line of (a). The histogram which shows the relationship between the incident angle of the light ray in the organic photoelectric conversion element shown in FIG. 1, and the absorbed light quantity in a photoelectric converting layer. The graph which shows the relationship between the vertex angle of the re-reflective layer shown in FIG. 2, a photoelectric conversion rate, a re-emission rate, and an electrode loss rate. The graph which shows the relationship between the apex angle of the re-reflection layer shown in FIG. 3, a photoelectric conversion rate, a re-emission rate, and an electrode loss rate. Explanatory sectional drawing which shows the 1st example of the specific structure of the organic photoelectric conversion element shown in FIG. Explanatory sectional drawing which shows the 2nd example of the specific structure of the organic photoelectric conversion element shown in FIG. Explanatory sectional drawing which shows the example of 1 structure of the conventional organic photoelectric conversion element. Explanatory sectional drawing which shows the other structural example of the conventional organic photoelectric conversion element. Explanatory sectional drawing which shows the other structural example of the conventional organic photoelectric conversion element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11,21,31,41,51 ... Organic photoelectric conversion element, 2 ... Transparent substrate, 3 ... Transparent electrode layer, 4 ... Photoelectric conversion layer, 5 ... Metal electrode layer, 6 ... Re-reflection layer.

Claims (8)

A transparent substrate having one surface as a light-receiving surface, a transparent electrode layer formed on the surface of the transparent substrate opposite to the light-receiving surface, and a photoelectric conversion layer having an organic dye formed on the transparent electrode; In an organic photoelectric conversion element comprising a metal electrode layer formed on the photoelectric conversion layer,
An organic photoelectric conversion element comprising a re-reflection layer that re-reflects a light beam reflected by the metal electrode layer on the light-receiving surface of the transparent substrate.   The organic photoelectric conversion element according to claim 1, wherein the re-reflection layer is formed integrally with the transparent substrate.   The organic photoelectric conversion element according to claim 1, wherein the re-reflection layer includes a plurality of conical protrusions or conical recesses.   The organic photoelectric conversion element according to claim 3, wherein the pyramids are regular quadrangular pyramids, and their bases are in contact with each other.   5. The organic photoelectric conversion device according to claim 4, wherein the regular quadrangular pyramid has a base length in a range of 10 to 100 μm and a vertex angle in a range of 20 to 150 °.   4. The organic photoelectric conversion element according to claim 3, wherein the cone is a cone and overlaps each other at an outer portion of a square inscribed in a bottom surface.   7. The organic photoelectric conversion device according to claim 6, wherein the cone has a side length of 10 to 100 [mu] m inscribed in the bottom and a vertex angle of 20 to 150 [deg.].   The organic photoelectric conversion element according to any one of claims 1 to 7, wherein the re-reflection layer includes an ultraviolet blocking material.

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