WO2007015380A1

WO2007015380A1 - Transparent conductive fine particles, method for producing same, and electrooptical device

Info

Publication number: WO2007015380A1
Application number: PCT/JP2006/314535
Authority: WO
Inventors: Takayuki Abe; Yuuji Honda
Original assignee: Youtec Co., Ltd.
Priority date: 2005-08-03
Filing date: 2006-07-18
Publication date: 2007-02-08
Also published as: JP2007042419A

Abstract

Transparent conductive ultrafine particles exhibiting high conductivity and light transmittance or transparent conductive fine particles produced by coating fine particles with a transparent conductive thin film, its production process and an electrooptical device. The transparent conductive fine particles are characterized in that the surfaces of fine particles (3) are respectively coated with transparent conductive ultrafine particles having smaller diameters than the fine particles or a transparent conductive thin film by rotating a vacuum container (1) having a polygonal inner cross-section about the axis of rotation substantially perpendicular to the cross-section, thereby performing sputtering while stirring or rotating the fine particles (3) in the vacuum container (1).

Description

Description: Transparent conductive fine particles and method for producing the same, electro-optical device 1. Technical Field

The present invention relates to transparent conductive fine particles, a method for producing the same, and an electro-optical device, and in particular, transparent conductive ultrafine particles or transparent conductive thin films having good conductivity and high light transmittance coated with the fine particles. The present invention relates to fine particles and a method for producing the same, and also relates to an electro-optical device using the transparent conductive fine particles.

2. Background art

Powder is a very attractive sample for both basic and application, and is currently used in various fields. For example, the fineness of powder is used to make a cosmetic foundation, and fine particles of flylite are used as a magnetic material applied to magnetic tape to form a single magnetic domain. In addition, the characteristics of powders include the size of the surface area.

3. Disclosure of the Invention

As described above, since it is a material with great potential, there is a need for new material development technology that further modifies the functional material on the powder surface to express high functionality and new functions.

The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide transparent conductive ultrafine particles or transparent conductive thin films coated with fine particles with good conductivity and high light transmittance. It is to provide a conductive fine particle, a manufacturing method thereof, and an electro-optical device.

In order to solve the above problems, the transparent conductive fine particles according to the present invention are characterized in that the surface of the fine particles is covered with transparent conductive ultrafine particles or a transparent conductive thin film having a particle diameter smaller than that of the fine particles. The transparent conductive fine particles according to the present invention agitate or rotate the fine particles in the vacuum vessel by rotating a vacuum vessel having a polygonal cross-sectional shape with a rotation axis in a direction substantially perpendicular to the cross-section. The surface of the fine particles is coated with transparent conductive ultrafine particles or a transparent conductive thin film having a particle diameter smaller than that of the fine particles by performing sputtering while performing the process.

Incidentally, as the transparent conductive ultra-fine particles or the transparent conductive thin film, ITO (indium tin oxide; Indium Tin Oxide) fine particles or IT_〇 thin, S N_〇 ₂ ultrafine particles or S N_〇 ₂ thin film, the light can pass It is also possible to use metal ultrafine particles that are thin enough or metal thin films that are thin enough to transmit light. Examples of the metal used for the metal ultrafine particles or the metal thin film include Au, Pt, Ti, Ag, Al, Cu, and Pd.

In the transparent conductive fine particle according to the present invention, it is preferable that the fine particle is made of any one of an insulator, a light emitting material and a phosphor. As the insulator, A 1 ₂ 0 _3, S I_〇 _2, T I_〇 _2, Z n O, Z R_〇 _2, it is also possible to have use of any polymer.

The electro-optical device according to the present invention includes a powder made of an aggregate of transparent conductive fine particles, a ground potential electrode connected to the powder,

Comprising

The transparent conductive fine particles are obtained by coating the surface of fine particles with transparent conductive ultrafine particles or a transparent conductive thin film having a particle size smaller than that of the fine particles.

The fine particles are a luminescent material or a fluorescent material.

Comprising

The transparent conductive fine particles are sputtered while rotating or rotating the vacuum container having a polygonal cross-sectional shape about a direction substantially perpendicular to the cross-section as the rotation axis. The transparent conductive ultrafine particles having a particle diameter smaller than the fine particles or the transparent conductive material are formed on the surface of the fine particles. It is coated with an electric thin film,

The fine particles are a luminescent material or a fluorescent material.

The electro-optical device according to the present invention includes a powder made of an aggregate of transparent conductive fine particles, a first electrode connected to the powder,

A second electrode connected to the powder;

A power supply for applying a voltage between the first electrode and the second electrode;

Comprising

The fine particles are a luminescent material or a fluorescent material.

A second electrode connected to the powder;

Comprising

The transparent conductive fine particles are sputtered while rotating or rotating the vacuum container having a polygonal cross-sectional shape about a direction substantially perpendicular to the cross-section as the rotation axis. The surface of the fine particles is coated with transparent conductive ultrafine particles or a transparent conductive thin film having a smaller particle diameter than the fine particles,

The fine particles are a luminescent material or a fluorescent material.

The method for producing transparent conductive fine particles according to the present invention includes a step of preparing fine particles, a step of containing the fine particles in a vacuum container having a polygonal internal shape of a cross section substantially parallel to the direction of gravity,

By rotating the vacuum vessel about a direction substantially perpendicular to the cross-section, the fine particles in the vacuum vessel are sputtered while stirring or rotating the fine particles in the surface of the fine particles. A step of coating a transparent conductive ultrafine particle having a small diameter or a transparent conductive thin film; It is characterized by comprising.

As described above, according to the present invention, there are provided transparent conductive fine particles in which fine particles are coated with transparent conductive ultrafine particles or a transparent conductive thin film having good conductivity and high light transmittance, a method for producing the same, and an electro-optical device. can do.

4. Brief description of the drawings

FIG. 1 is a configuration diagram showing an outline of a polygonal barrel sputtering apparatus used when manufacturing transparent conductive fine particles according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 3 of the present invention.

Figures 4 (a) and 4 (b) show the XRD pattern of the ITO thin film deposited on the glass substrate.

Figure 5 (a) shows the UV-visible absorption spectrum of the ITO thin film with oxygen content of 0, 10 and 20%. Figure 5 (b) shows the UV-visible absorption spectrum of the sample after annealing. It is a figure which shows a spectrum.

Figure 6 shows the electrical resistance of ITO thin films with oxygen content of 0, 10 and 20%.

Figure 7 is a photograph showing the appearance of the deposited sample.

Fig. 8 shows the results of measuring the UV-visible absorption spectrum of transparent conductive particles.

5. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)

FIG. 1 is a configuration diagram showing an outline of a polygonal parel sputtering apparatus used when producing transparent conductive fine particles according to Embodiment 1 of the present invention. This polygonal barrel The putter device is a device for coating the surface of fine particles (powder) with ultrafine particles having a smaller particle diameter than the fine particles (the ultrafine particles herein are fine particles having a smaller particle size than the fine particles) or a thin film. is there.

The polygonal barrel sputtering apparatus has a vacuum vessel 1 for coating fine particles (powder sample) 3 with ultrafine particles or a thin film, and this vacuum vessel 1 has a cylindrical portion 1 a having a diameter of 20 O mm and an inside thereof. The installed cross section has a hexagonal barrel (hexagonal barrel) 1 b. The cross section shown here is a cross section substantially parallel to the direction of gravity. In the present embodiment, the hexagonal barrel 1b is used. However, the present invention is not limited to this, and a polygonal barrel other than the hexagon can be used.

The vacuum vessel 1 is provided with a rotating mechanism (not shown). By rotating the hexagonal barrel 1 b as shown by the arrow by the rotating mechanism, fine particles (powder sample) in the hexagonal barrel 1 b are provided. 3) Coating is performed while stirring or rotating 3). A rotation axis when the hexagonal barrel is rotated by the rotation mechanism is an axis parallel to a substantially horizontal direction (a direction perpendicular to the gravity direction). Also, in the vacuum container 1, a sputtering target 2 made of ITO (10 wt% Sn 0 ₂ ) is arranged on the central axis of the cylinder, and the angle of the target 2 can be changed freely. It is configured. As a result, when the coating process is performed while the hexagonal barrel lb is rotated, the target 2 can be directed in the direction in which the powder sample 3 is positioned, thereby increasing the sputtering efficiency. One end of a pipe 4 is connected to the vacuum vessel 1, and one side of the first valve 12 is connected to the other end of the pipe 4. One end of the pipe 5 is connected to the other side of the first valve 12, and the other end of the pipe 5 is connected to the intake side of the turbo molecular pump (TMP) 10. The exhaust side of the turbo molecular pump 10 is connected to one end of the pipe 6, and the other end of the pipe 6 is connected to one side of the second valve 13. The other side of the second valve 13 is connected to one end of the pipe 7, and the other end of the pipe 7 is connected to the pump (RP) 11. Pipe 4 is connected to one end of pipe 8, and the other end of pipe 8 is connected to one side of third valve 14 The The other side of the third valve 14 is connected to one end of the pipe 9, and the other end of the pipe 9 is connected to the pipe 7.

This apparatus is provided with a heater 17 for heating the powder sample 3 in the vacuum vessel 1L. In addition, this apparatus includes a vibrator 18 for applying vibration to the powder sample 3 in the vacuum vessel 1. The apparatus also includes a pressure gauge 19 that measures the internal pressure of the vacuum vessel 1. The apparatus also includes an oxygen gas introduction mechanism 15 that introduces nitrogen gas into the vacuum vessel 1 and an argon gas introduction mechanism 16 that introduces argon gas into the vacuum vessel 1. In addition, this apparatus includes a high-frequency application mechanism (not shown) that applies a high frequency between the target 2 and the hexagonal barrel 1 b.

Next, a method for producing transparent conductive fine particles in which the fine particle 3 is coated with a transparent conductive thin film using the polygon barrel sputtering apparatus will be described.

First, about 5 grams of powder sample 3 is introduced into the hexagonal barrel 1b 內. Particle diameter as the powder sample 3 were used A 1 ₂ 0 ₃ powder 8 0 mu m. For target 2, ITO was used. In this embodiment, A 1 ₂ 0 ₃ powder is used. However, the present invention is not limited to this, and other materials such as A 1 ₂ 0 ₃ , S i 0 ₂ , T i 0 _{2 are used.} , an insulator such as Z n O, Z R_〇 _2, polymer light emitter, it is also possible to use a powder comprising a fluorescent body. If this polygonal barrel sputtering method is used, it is possible to cover a wide range of material powders with a transparent conductive thin film. Next, a high vacuum state is created in the hexagonal barrel 1b using the turbo molecular pump 10 and the inside of the hexagonal barrel is heated up to 20 ° C with the heater 17 while 5 X 1 the pressure was reduced to 0- ⁴ P a. Thereafter, argon is introduced into the hexagonal barrel 1 b by the argon gas supply mechanism 16. At this time, the pressure in the hexagonal barrel is about 2 Pa. In some cases, a mixed gas of argon and oxygen may be introduced into the hexagonal barrel 1b. Then, the hexagonal barrel 1b is rotated at 3.5 rpm at 35 rpm for 18 minutes by the rotation mechanism, thereby rotating and stirring the powder sample 3 in the hexagonal barrel 1b. At that time, the target is directed in the direction in which the powder sample is located. Then, target 2 and ITO is sputtered on the surface of the powder sample 3 by applying a high frequency to the hexagonal barrel 1 b. In this way, the surface of the fine particles 3 can be coated with the ITO thin film. '

According to the first embodiment, the powder itself can be rotated and stirred by rotating the hexagonal barrel itself, and the powder can be periodically dropped by gravity by making the barrel hexagonal. it can. For this reason, the stirring efficiency can be dramatically improved, and aggregation of the powder due to moisture or electrostatic force, which is often a problem when handling the powder, can be prevented. In other words, stirring by rotation and pulverization of the agglomerated powder can be performed simultaneously and effectively. Therefore, it is possible to coat the ITO thin film on fine particles having a very small particle diameter. Specifically, it is possible to coat ultrafine particles or thin films on fine particles having a particle size of 50 μm or less. In the present embodiment, the heater 17 is attached to the outside of the vacuum vessel 1, and the hexagonal barrel 1 b can be heated to 200 ° C. by the heater 17. For this reason, when the inside of the vacuum vessel 1 is evacuated, the hexagonal parel is heated by the heater 17, whereby the water in the hexagonal barrel can be vaporized and exhausted. Therefore, since water that is a problem when handling powder #: can be removed from the hexagonal parel, powder agglomeration can be more effectively prevented.

In the present embodiment, a vibrator 18 is attached to the outside of the vacuum vessel 1, and vibration can be applied to the powder 3 in the hexagonal barrel by the vibrator 18. This makes it possible to more effectively prevent agglomeration, which is a problem when handling powder.

In this embodiment, since the surface of the powder sample 3 is coated with the fine particles by the polygonal barrel sputtering apparatus, it is not necessary to treat the waste liquid as in the conventional plating method, and the load on the environment can be reduced. There is an advantage.

In the first embodiment, vibration is applied to the powder 3 in the hexagonal barrel by the vibrator 18, but instead of the vibrator 18 or in addition to the vibrator 18, the hexagonal barrel With the rod-shaped member housed inside, It is also possible to apply vibration to the powder 3 by rotating the reel. This makes it possible to more effectively prevent agglomeration, which is a problem when handling powder.

Further, in this first embodiment, is used a I TO as a transparent conductive thin film or a transparent conductive ultrafine particles coated onto microparticles, the rather than limited thereto, S n0 ₂ thin film or S N_〇 ₂ Ultrafine particles, metal thin films that are thin enough to transmit light, or metal ultrafine particles that are thin enough to transmit light can also be used. As the metal used in the metal thin film or the metal ultrafine particles, for example, Au Pt, Ti, Ag, A and Cu, Pd and the like are preferable.

In addition, examples of the use of the transparent conductive fine particles described above include a conductive spacer of a display typified by liquid crystal.

(Embodiment 2)

This electro-optical device includes a powder 44 made of an aggregate of transparent conductive fine particles 43. The transparent conductive fine particles 43 have fine particles 41 and a transparent conductive thin film 42 covering the fine particles 41, and are produced by the same method as in the first embodiment.

The fine particles 41 are made of a light emitter or phosphor such as an inorganic EL element (electroluminescence element; electroluminescence). The fine particles of the inorganic EL element are formed by pulverizing and adding a butter made of an inorganic EL material to form fine particles.

The transparent conductive thin film, it is possible to use thin metal film to the extent that I TO thin, S N_〇 ₂ thin film, the light is Ru transparently. Examples of the metal used for the metal thin film include A11, Pt, Ti, Ag, Al, Cu, and Pd.

A part of the powder 44 is connected to an electrode 45, and the electrode 45 is connected to a ground potential. Charge may occur in the aggregate of transparent conductive fine particles 43, which may cause aggregation. On the other hand, in the present embodiment, a part of the powder 44 is connected to the electrode 45 and this electrode 45 is connected to the ground potential, so that the charge can be removed.

(Embodiment 3)

This electro-optical device is provided with a powder 54 consisting of an aggregate of transparent conductive fine particles 53. The transparent conductive fine particles 53 have fine particles 51 and a transparent conductive thin film 52 covering the fine particles 51, and are produced by the same method as in the first embodiment.

The fine particles 41 are made of a light emitter or phosphor such as an inorganic EL element. The fine particles of the inorganic EL element are formed by pulverizing and processing a balta made of an inorganic EL material to form fine particles.

-Further, since the transparent conductive thin film is the same as that of the second embodiment, the description thereof is omitted.

A part of the powder 54 is connected to the first electrode 55, and another part of the powder 54 is connected to the second electrode 56. Between the first electrode 55 and the second electrode 56, a power source 57 for applying a voltage and a switch 58 are disposed. When the switch 58 is turned on, a direct current voltage is applied to the powder 54 between the first electrode 55 and the second electrode 56 by the power source 57, and the transparent conductive particles 51 are made of light-emitting material or phosphor. As a result, a fine voltage 51 emits light or fluorescence.

[Example]

Described that was formed by the sputtering device not S i 0 polygonal barrel an ITO thin film ₂ on a glass substrate.

First, in order to examine the deposition conditions of the ITO thin film, the structure and physical properties of the ITO thin film were examined when the oxygen content was changed to 0%, 10%, and 20% of the total pressure. So Other use target I TO (10 wt ⁰ / oS N_〇 _2), output 50 W, sputtering Taringu time 60 min, and fixed with the conditions of room temperature. When the oxygen content is 0%, the argon flow rate is 20 sccm, when the oxygen content is 10%, the argon flow rate is 18 sccm, the oxygen flow rate is 2 sccm, and when the oxygen content is 20%, the argon flow rate. Was 16 sccm and the oxygen flow rate was 4 sccm.

Figure 4 shows the XRD pattern of the ITO thin film formed on the glass substrate under the above conditions. Figure 4 (a) shows the XRD pattern of the ITO thin film when the oxygen content is 0%. Fig. 4 (b) shows the XRD pattern of the ITO thin film when the oxygen content is 20%.

In all of the film formation conditions (oxygen quantity 0, 10, 20%), the observed diffraction peaks can be attributed to I n ₂ 〇 ₃ type crystal structure, has almost the same in the three samples for the angle of diffraction peak It was. From this, it was found that the ITO thin film can be formed by reactive sputtering.

Figure 5 (a) shows the UV-visible absorption spectrum of the ITO thin film with oxygen content of 0, 10, and 20%, respectively. The ITO thin film 21 with an oxygen content of 0% showed absorption over the entire visible light range, but the ITO thin films 22 and 23 with an oxygen content of 10% and 20% had almost no absorption above 400 nm.

The sample after depositing the above-mentioned ITO thin film was annealed at 450 ° C for 120 minutes in an Ar atmosphere. Figure 5 (b) shows the UV-visible absorption spectrum of the sample after annealing.

The XRD pattern after annealing showed no noticeable changes in the diffraction peak angle and intensity compared to before annealing (for example, the XRD pattern with 0% oxygen content is shown in Fig. 4). However, as shown in Fig. 5 (b), the UV-visible absorption spectrum no longer absorbs in the visible light region even with the sample 24 with an oxygen content of 0%, and all samples (ITO thin film 25 with an oxygen content of 10%, It was found that the ITO thin film with an oxygen content of 20% showed a high transmittance for visible light.

Next, the conductivity of the ITO thin film was measured. The measurement was performed by the DC two-terminal method, and In metal was used as the terminal contact. The distance between terminals is 1 mm, the sample width is 10 mm, The film thickness is 80-120 nm. Figure 6 shows the measurement results. Fig. 6 shows the electrical resistance of ITO thin films with oxygen content of 0, 10, and 20%.

In the sample before annealing, the resistance value decreases as the oxygen content decreases, and shows about 6 Ω at the oxygen content of 0%. , Ri simply Do a 5 X 10- ⁴ Q cm in terms of resistivity, a sufficiently low resistance value is obtained even in comparison to other literature. In the measurement results of the samples after annealing, the tendency of change in resistance value was the same as before annealing, but all showed lower resistance values. The smallest oxygen content of 0% showed about 2 Ω.

From the above results, it was found that it is desirable to perform annealing after the film formation at an oxygen content of 0% for the formation of an ITO thin film exhibiting high light transmittance and good conductivity. Next, an ITO thin film was formed on the surface of the fine powder particles to produce transparent conductive fine particles.

An IτO thin film was formed on the powder surface by barrel sputtering under the condition of 0% oxygen content. The A 1 ₂ 0 ₃ powder particle size 80 mu m was introduced into approximately 5 g hexagonal path in barrels at a time, having conducted a 1 for 80 minutes sputtering at a rotation speed of 3. 5 rpm. Other conditions are the same as those described above. The sample after film formation was annealed at 450 ° C for 120 minutes in an Ar atmosphere.

Figure 7 is a photograph showing the appearance of the deposited sample. In Fig. 7, the non-deposited sample (unmodified sample) 27 is white, while the transparent conductive fine particles after sputtering (sputtering only) 28 is light brown. When the transparent conductive fine particles were annealed, the annealed transparent conductive fine particles 29 became lighter brown than the transparent conductive fine particles 28 of only sputtering. This is similar to the trend on glass substrates.

Doing XRD measurement of the transparent conductive fine particles, a peak attributable to the small fence I n ₂ 0 ₃ in the diffraction peaks of A l ₂ 0 ₃ was observed. From the X-ray fluorescence analysis, it was detected at a ratio of I n: S n = 87: 1 3 w t ° / ₀ . The mixing ratio of the target is I n: S n = 88: 1 2 wt%, and it is thought that ITO with the same composition as the target is formed.

Next, the ultraviolet-visible absorption spectrum of the transparent conductive fine particles was measured. Measurement The results are shown in FIG. As shown in FIG. 8, A 1 ₂ 0 ₃ particles 30 serving as a carrier have low absorption over the entire visible light region. On the other hand, the transparent conductive fine particles 31 after annealing showed a high transmittance in the visible light range, although the absorbance was slightly higher than that of the carrier particles 30.

Furthermore, the electrical resistance of the transparent conductive fine particles was measured. The measurement was performed by sandwiching about 0.05 g of transparent conductive fine particles between flat plates of metal (A 1), and the electrical resistance between the flat plates was measured by the two-terminal method. The resistance value of the transparent conductive fine particles coated with the ITO thin film was 5 Ω, and it was found that the resistance value decreased by annealing as in the case of the flat plate (By the way, unmodified A 1 ₂ 0 ₃ particles were also measured, It was out of the measuring range of the instrument (100MΩ or more).) Metal (P t) modified A 1 ₂ 0 ₃ particles shows a degree 4 Omega 0. and you measured. The resistance value is about 10 times that of metal, and it can be said that the resistance value is sufficiently small.

Overall, it was confirmed that the transparent conductive fine particles coated with the ITO thin film can be formed by barrel sputtering.

The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. For example, it is possible to appropriately change the film forming conditions for forming an ITO thin film on fine particles.

Claims

The scope of the claims

1. A transparent conductive fine particle, wherein the surface of the fine particle is coated with a transparent conductive ultra fine particle or a transparent conductive thin film having a particle diameter smaller than that of the fine particle.

2. Sputtering while rotating or rotating the fine particles in the vacuum vessel by rotating a vacuum vessel having an internal cross-sectional shape of a polygon with the direction substantially perpendicular to the cross-section as a rotation axis. A transparent conductive fine particle, wherein the surface of the fine particle is coated with a transparent conductive ultra fine particle or a transparent conductive thin film having a particle diameter smaller than that of the fine particle.

3. The transparent conductive fine particle according to claim 1 or 2, wherein the fine particle comprises any one of an insulator, a light emitter and a phosphor.

4. a powder composed of an aggregate of transparent conductive fine particles;

A ground potential electrode connected to the powder;

Comprising

An electro-optical device, wherein the fine particles are a luminescent material or a fluorescent material.

5. a powder composed of an aggregate of transparent conductive fine particles;

A ground potential electrode connected to the powder;

Comprising

6. a powder composed of an aggregate of transparent conductive fine particles;

A first electrode connected to the powder; A second electrode connected to the powder;

Comprising

7. A powder comprising an aggregate of transparent conductive fine particles;

A first electrode connected to the powder;

A second electrode connected to the powder;

Comprising

8. Preparing the fine particles;

Storing the fine particles in a vacuum vessel having a polygonal internal shape in a cross section substantially parallel to the direction of gravity; and

By rotating the vacuum vessel about a direction substantially perpendicular to the cross section as a rotation axis, the fine particles in the vacuum vessel are sputtered while being stirred or rotated, so that the fine particles are formed on the surface of the fine particles from the fine particles. A step of coating a transparent conductive ultrafine particle having a small diameter or a transparent conductive thin film;

A process for producing transparent conductive fine particles, comprising: