JP2012089510A - Transparent conductive particles, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide transparent conductive particles having particles coated by transparent conductive ultra fine particles or a transparent conductive thin film with good conductivity and high light transmittance, its manufacturing method, and an electrophotographic apparatus.SOLUTION: Transparent conductive particles are coated by transparent conductive ultra fine particles with smaller particle diameter than particles 3 or a transparent conductive thin film on a surface of the particles 3, by performing sputtering while the particles 3 in a vacuum container 1 is agitated or rotated, by rotating the vacuum container 1, having an internal cross section shape of a polygon, around an approximately vertical direction against the section surface as an axis of rotation.

Description

  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 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. Further, the present invention relates to an electro-optical device using the transparent conductive fine particles.

  Powder is a very attractive sample both fundamentally and in application, and is currently used in various fields. For example, the fineness of powder is used for cosmetic foundations, and ferrite fine particles are used as a magnetic material applied to magnetic tape to form a single magnetic domain. In addition, there is a size of the surface area in the characteristics of the powder, and a fine particle catalyst using this is also made.

  As described above, since it is a material with great potential, there is a need for a new material development technology that further modifies a functional material on the powder surface to express high functions 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. An object of the present invention is to provide fine particles, 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 surfaces of the fine particles are coated 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 an internal cross-sectional shape of a polygon with the substantially vertical direction as a rotation axis. 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 thin ITO film, thin metal than to the extent that SnO ₂ ultrafine particles or SnO ₂ thin film, the light can pass It is also possible to use a metal thin film that is thin enough to transmit fine particles or 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 emitter, and a phosphor. As the insulator, any one of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ , and a polymer can be used.

The electro-optical device according to the present invention includes a powder composed 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 the fine particles with transparent conductive ultrafine particles having a smaller particle diameter than the fine particles or a transparent conductive 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 composed of an aggregate of transparent conductive fine particles,
A ground potential electrode connected to the powder;
Comprising
The transparent conductive fine particles are sputtered while stirring or rotating the fine particles in the vacuum vessel by rotating a vacuum vessel having a polygonal cross-sectional shape about a direction perpendicular to the cross-section as a rotation axis. The surface of the fine particles is coated with transparent conductive ultrafine particles having a smaller particle diameter than the fine particles or a transparent conductive 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 composed 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 transparent conductive fine particles are obtained by coating the surface of the fine particles with transparent conductive ultrafine particles having a smaller particle diameter than the fine particles or a transparent conductive 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 composed 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 transparent conductive fine particles are sputtered while stirring or rotating the fine particles in the vacuum vessel by rotating a vacuum vessel having a polygonal cross-sectional shape about a direction perpendicular to the cross-section as a rotation axis. The surface of the fine particles is coated with transparent conductive ultrafine particles having a smaller particle diameter than the fine particles or a transparent conductive thin film,
The fine particles are a luminescent material or a fluorescent material.

The method for producing transparent conductive fine particles according to the present invention comprises a step of preparing fine particles,
Storing the fine particles in a vacuum container 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, sputtering is performed while stirring or rotating the fine particles in the vacuum vessel, so that the surface of the fine particles has a particle size smaller than that of the fine particles. Coating small transparent conductive ultrafine particles or transparent conductive thin film;
It is characterized by comprising.

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

It is a block diagram which shows the outline of the polygonal barrel sputtering apparatus used when manufacturing the transparent conductive fine particle by embodiment of this invention. FIG. 6 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 3 of the present invention. (A), (b) is a figure which shows the XRD pattern of the ITO thin film formed into a film on the glass substrate. (A) is a figure which shows the ultraviolet-visible absorption spectrum of each ITO thin film of oxygen amount 0,10,20%, (b) is a figure which shows the ultraviolet-visible absorption spectrum of the sample after annealing. It is a figure which shows the electrical resistance of each ITO thin film of oxygen amount 0,10,20%. It is a photograph which shows the external appearance of the film-formed sample. It is a figure which shows the result of having measured the ultraviolet visible absorption spectrum of transparent electroconductive fine particles.

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 barrel sputtering apparatus used when producing transparent conductive fine particles according to Embodiment 1 of the present invention. This polygonal barrel sputtering apparatus is used to coat the surface of fine particles (powder) with ultrafine particles having a smaller particle diameter than the fine particles (here, ultrafine particles are particles having a smaller particle diameter than the fine particles) or a thin film. Device.

  The polygonal barrel sputtering apparatus has a vacuum vessel 1 for coating fine particles (powder sample) 3 with ultrafine particles or a thin film. The vacuum vessel 1 has a cylindrical portion 1a having a diameter of 200 mm and a cross section installed in the inside thereof. And a hexagonal barrel (hexagonal barrel) 1b. 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 also be used.

The vacuum vessel 1 is provided with a rotating mechanism (not shown). By rotating the hexagonal barrel 1b as shown by the arrow by this rotating mechanism, the fine particles (powder sample) 3 in the hexagonal barrel 1b are removed. The coating process is performed while stirring or rotating. A rotation axis when the hexagonal barrel is rotated by the rotation mechanism is an axis substantially parallel to the horizontal direction (perpendicular to the gravity direction). In addition, a sputtering target 2 made of ITO (10 wt% SnO ₂ ) is disposed on the central axis of the cylinder in the vacuum vessel 1, and the target 2 is configured so that the angle can be freely changed. Thus, when the coating process is performed while rotating the hexagonal barrel 1b, the target 2 can be directed in the direction in which the powder sample 3 is located, 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. The pipe 4 is connected to one end of the pipe 8, and the other end of the pipe 8 is connected to one side of the third valve 14. 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 includes a heater 17 for heating the powder sample 3 in the vacuum vessel 1. In addition, the 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 container 1 and an argon gas introduction mechanism 16 that introduces argon gas into the vacuum container 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 1b.

Next, the manufacturing method of the transparent conductive fine particle which coat | covers the transparent conductive thin film on the fine particle 3 using the said polygon barrel sputtering apparatus is demonstrated.
First, about 5 grams of the powder sample 3 is introduced into the hexagonal barrel 1b. As the powder sample 3, Al ₂ O ₃ powder having a particle diameter of 80 μm was used. Moreover, ITO was used for the target 2. In the present embodiment, Al ₂ O ₃ powder is used. However, the present invention is not limited to this, and other materials such as Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ , It is also possible to use a powder made of an insulator such as a polymer, a light emitter, and a phosphor. If this polygonal barrel sputtering method is used, it is possible to coat a wide range of material powders with a transparent conductive thin film.

Next, a high vacuum state was created in the hexagonal barrel 1 b using the turbo molecular pump 10, and the hexagonal barrel was decompressed to 5 × 10 ⁻⁴ Pa while heating the hexagonal barrel to 200 ° C. with the heater 17. Thereafter, argon is introduced into the hexagonal barrel 1b by the argon gas supply mechanism 16. The pressure in the hexagonal barrel at this time is about 2 Pa. In some cases, a mixed gas of argon and oxygen may be introduced into the hexagonal barrel 1b. The powder sample 3 in the hexagonal barrel 1b is rotated and agitated by rotating the hexagonal barrel 1b at 50 W for 180 minutes at 3.5 rpm by the rotation mechanism. At that time, the target is directed in the direction in which the powder sample is located. Then, ITO is sputtered on the surface of the powder sample 3 by applying a high frequency between the target 2 and the hexagonal barrel 1b by a high frequency application mechanism. 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 further forming the hexagonal barrel. . 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. That is, 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 a thin film on fine particles having a particle size of 50 μm or less.

  Moreover, in this Embodiment, the heater 17 is attached to the outer side of the vacuum vessel 1, The hexagonal barrel 1b can be heated to 200 degreeC with this heater 17. FIG. For this reason, when the inside of the vacuum vessel 1 is evacuated, by heating the hexagonal barrel with the heater 17, moisture in the hexagonal barrel can be vaporized and exhausted. Therefore, since water which is a problem when handling the powder can be removed from the hexagonal barrel, the aggregation of the powder can be more effectively prevented.

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

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

  In the first embodiment, the vibrator 18 vibrates the powder 3 in the hexagonal barrel. However, instead of the vibrator 18 or in addition to the vibrator 18, a rod-shaped member is placed in the hexagonal barrel. It is also possible to apply vibration to the powder 3 by rotating the hexagonal barrel in the accommodated state. This makes it possible to more effectively prevent agglomeration, which is a problem when handling powder.

In the first embodiment, ITO is used as the transparent conductive thin film or the transparent conductive ultrafine particle coated on the fine particles. However, the present invention is not limited to this, and the SnO ₂ thin film or the SnO ₂ ultrafine particle, light It is also possible to use a metal thin film that is thin enough to transmit light or a metal ultrafine particle that is thin enough to transmit light. Examples of the metal used in the metal thin film or metal ultrafine particle include Au, Pt, Ti, and Ag. Al, Cu, Pd, etc. are preferable.

  Moreover, as an application of the above-mentioned transparent conductive fine particles, for example, a conductive spacer of a display typified by liquid crystal can be mentioned.

(Embodiment 2)
FIG. 2 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 2 of the present invention.
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-emitting body or phosphor such as an inorganic EL element (electroluminescence element). The fine particles of the inorganic EL element are formed by pulverizing and processing a bulk made of an inorganic EL material.

The transparent conductive thin film may be an ITO thin film, a SnO ₂ thin film, or a metal thin film that is thin enough to transmit light. Examples of the metal used for the metal thin film include Au, Pt, Ti, Ag, Al, Cu, and Pd.

  A part of the powder 44 is connected to an electrode 45, and this electrode 45 is connected to the ground potential.

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

(Embodiment 3)
FIG. 3 is a cross-sectional view schematically showing an electro-optical device according to Embodiment 3 of the present invention.
The electro-optical device includes a powder 54 made 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 that covers 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 emitting body such as an inorganic EL element or a phosphor. The fine particles of the inorganic EL element are formed by pulverizing and processing a bulk made of an inorganic EL material.

  Moreover, since the said transparent conductive thin film is the same as that of Embodiment 2, description is abbreviate | omitted.

  A part of the powder 54 is connected to the first electrode 55, and the other part of the powder 54 is connected to the second electrode 56. A power supply 57 and a switch 58 for applying a voltage are disposed between the first electrode 55 and the second electrode 56. 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 direct current voltage is applied to the fine particles 51 made of a light emitter or phosphor through the transparent conductive thin film 52. As a result, the fine particles 51 emit light or fluorescence.

An explanation will be given of forming an ITO thin film on a SiO ₂ glass substrate by a sputtering apparatus which is not a polygonal barrel.
First, in order to examine the film forming 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% with respect to the total pressure. Other than that, the target used was fixed under the conditions of ITO (10 wt% SnO ₂ ), output 50 W, sputtering time 60 minutes, and 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 and the oxygen flow rate is 2 sccm. When the oxygen content is 20%, the argon flow rate is 16 sccm. Was 4 sccm.

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

Under all film forming conditions (oxygen content 0, 10, 20%), the observed diffraction peak could be attributed to the In ₂ O ₃ type crystal structure, and the angles of the diffraction peaks were almost the same for the three samples. . From this, it was found that the ITO thin film can be formed by reactive sputtering.

  Fig.5 (a) is a figure which shows the ultraviolet-visible absorption spectrum of each ITO thin film of oxygen amount 0,10,20%. The ITO thin film 21 having an oxygen content of 0% showed absorption over the entire visible light range, but the ITO thin films 22 and 23 having an oxygen content of 10% and 20% had almost no absorption above 400 nm.

The sample after forming the ITO thin film was annealed at 450 ° C. for 120 minutes in an Ar atmosphere. The ultraviolet-visible absorption spectrum of the sample after this annealing is shown in FIG.
The XRD pattern after annealing showed no noticeable changes in the angle and intensity of the diffraction peak compared to before annealing (for example, an XRD pattern with an oxygen content of 0% is shown in FIG. 4). However, as shown in FIG. 5B, the UV-visible absorption spectrum shows no absorption in the visible light region even with the sample 24 having an oxygen content of 0%, and all samples (ITO thin film 25 having an oxygen content of 10%, oxygen content 20%). It was found that the ITO thin film 26) exhibited 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 a terminal contact. The distance between the terminals is 1 mm, the sample width is 10 mm, and the film thickness is 80 to 120 nm. The measurement results are shown in FIG. FIG. 6 is a diagram showing the electrical resistance of each ITO thin film having an oxygen content of 0, 10, and 20%.

In the sample before annealing, the resistance value decreases as the oxygen content decreases, and shows about 6Ω when the oxygen content is 0%. When simply converted into specific resistance, it was 5 × 10 ⁻⁴ Ωcm, and a sufficiently low resistance value was obtained even when compared with other documents. In the measurement results of the samples after annealing, the tendency of resistance value change was the same as that before annealing, but all showed lower resistance values. The smallest oxygen content of 0% showed about 2Ω.

  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 film 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 ITO thin film was formed on the powder surface by barrel sputtering under the condition of 0% oxygen content. About 5 g of Al ₂ O ₃ powder having a particle size of 80 μm was introduced into a hexagonal barrel at a time, and sputtering was performed at a rotational speed of 3.5 rpm for 180 minutes. 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.

  FIG. 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 (sputtering only) 28 after sputtering has a light brown color. 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 only by sputtering. This is the same as the tendency on the glass substrate.

When XRD measurement of the transparent conductive fine particles was performed, a small peak attributable to In ₂ O ₃ was observed in the diffraction peak of Al ₂ O ₃ . Further, from the fluorescent X-ray analysis, it was detected at a ratio of In: Sn = 87: 13 wt%. The mixing ratio of the target is In: Sn = 88: 12 wt%, and it is considered that ITO having the same composition as the target is formed.

Next, the ultraviolet-visible absorption spectrum of the transparent conductive fine particles was measured. The measurement results are shown in FIG. As shown in FIG. 8, the Al ₂ O ₃ particles 30 serving as a carrier have a small 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 region although the absorbance was slightly larger than that of the carrier particles 30.

Furthermore, the electrical resistance of the transparent conductive fine particles was measured. In the measurement, about 0.05 g of transparent conductive fine particles were sandwiched between metal (Al) flat plates, and the electric resistance between the flat plates was measured by a two-terminal method. The resistance value of the transparent conductive fine particles coated with the ITO thin film was 5Ω, and it was found that the resistance value was decreased by annealing as in the case of the flat plate (By the way, the measurement of unmodified Al ₂ O ₃ particles was also performed, but the measurement range of the measuring instrument Outside (100 MΩ or more). When Al ₂ O ₃ particles modified with metal (Pt) are similarly measured, about 0.4Ω is shown. It can be said that the resistance value is about 10 times that of metal and a sufficiently small resistance value is achieved.

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

  In addition, this invention is not limited to the said embodiment and Example, It can be implemented in various changes within the range which does not deviate from the main point of this invention. For example, it is possible to appropriately change the film forming conditions for forming the ITO thin film on the fine particles.

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 1a ... Cylindrical part 1b ... Hexagonal barrel 2 ... Target 3 ... Fine particle (powder sample)
4-9 ... Piping 10 ... Turbo molecular pump (TMP)
11 ... Pump (RP)
12-14 ... First to third valves 15 ... Oxygen gas introduction mechanism 16 ... Argon gas introduction mechanism 17 ... Heater 18 ... Vibrator 19 ... Pressure gauge 21 ... ITO thin film 22 with 0% oxygen content ... ITO thin film with 10% oxygen content 23 ... ITO thin film with an oxygen content of 20% 24 ... Sample with an oxygen content of 0% 25 ... Sample with an oxygen content of 10% 26 ... Sample with an oxygen content of 20% 27 ... Unmodified sample 28 ... Transparent conductive fine particles 29 only for sputtering ... Annealing Transparent conductive fine particles 30... Al ₂ O ₃ particles 31. Transparent conductive fine particles after annealing

Claims (3)

The surface of fine particles made of any one of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ and polymer is coated with transparent conductive ultrafine particles or transparent conductive thin film having a particle diameter smaller than the fine particles. Transparent conductive fine particles. By rotating a vacuum vessel having an internal cross-sectional shape of a polygon about a direction substantially perpendicular to the cross-section as a rotation axis, Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO _{2 in the} vacuum vessel And the surface of the fine particles are 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 stirring or rotating the fine particles made of any one of the polymer and the polymer. Transparent conductive fine particles. Preparing fine particles comprising any of Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZnO, ZrO ₂ and a polymer;
Storing the fine particles in a vacuum container 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, sputtering is performed while stirring or rotating the fine particles in the vacuum vessel, so that the surface of the fine particles has a particle size smaller than that of the fine particles. Coating small transparent conductive ultrafine particles or transparent conductive thin film;
A process for producing transparent conductive fine particles, comprising: