JP4857427B2 - Light transmissive electrode for semiconductor device, semiconductor device, and method of manufacturing electrode - Google Patents

Description

  The present invention relates to a light transmissive electrode for a semiconductor device, a semiconductor device, and a method for manufacturing the electrode. More specifically, the present invention relates to a light transmissive electrode used in a semiconductor device that requires light transmissive at least on one side of the electrode. The present invention is directed to a semiconductor device including such a light transmissive electrode and a method for manufacturing such a light transmissive electrode.

A semiconductor device basically includes a pair of electrodes and a semiconductor layer disposed therebetween. The intended electronic function is achieved by the interaction between the semiconductor layer or the semiconductor layer and the electrode.
As a semiconductor device, there is a semiconductor device in which at least one electrode needs to have light transmittance. For example, there is a solar cell or an optical sensor that converts the energy of light incident from an electrode on one side into an electromotive force. There is an EL element that generates light by being supplied with power and emits light to the outside through a light-transmissive electrode. There is a liquid crystal display device that performs control such as blocking passage of light supplied from the outside.

For example, a Schottky battery having a three-layer structure of Al / ZnPc / Au has been proposed. (Refer nonpatent literature 1).
A light transmissive electrode used in such a semiconductor device is required to have high conductivity and transparency. Conventionally, a commonly used technique is ITO (indium tin oxide). The ITO electrode is widely used as a transparent electrode that is excellent in both transparency and conductivity and easy to handle. In addition to ITO, various transparent conductive materials are known. The Al electrode described in Non-Patent Document 1 described above also functions as a transparent electrode if the thickness is sufficiently reduced.
Technologies for improving the performance of transparent electrodes such as ITO have been proposed.

Non-Patent Document 2 reports that, in an organic EL element, the performance of the organic EL element is improved by applying polyaniline, which is a conductive polymer, on the ITO layer.
Non-Patent Document 3 uses PEDT (polyethylenedioxythiophene, referred to as PEDOT in this specification) as the conductive polymer in an electrode structure in which an ITO layer and a conductive polymer are combined as in Non-Patent Document 2. This has been reported to improve the performance of organic EL elements.
Technical paper `` Susanne Siebentritt et al., JUCTION EFFECTS IN PHTHALOCYANINE THIN SOLAR CELLS, Synthetic Metals, 41-43 (1991) 1173-1176 '' Technical paper `` Y. Yang et al., Polyaniline as a transparent electrode for polymer light-emitting diode: Lower operating voltage and higher efficiency, Applied Physics Letters, Vol. 64, No. 10, pp. 1245-1247 (1994) '' Technical paper `` SACarter et al., Polymeric anodes for improved polymer light-emitting diode performance, Applied Physics Letters, Vol. 70, No. 16, pp. 2067-2069 (1994) ''

However, it has been difficult to sufficiently achieve both transparency and electrical performance even with the above-described conventional light transmissive electrode.
For example, an ITO electrode or a transparent electrode obtained by combining an ITO electrode and a conductive polymer layer functions as an electrode having a large work function depending on the properties of ITO. However, depending on the structure and application of the semiconductor device, a transparent electrode having a small work function may be required. For such purposes, ITO transparent electrodes could not be used.
In addition, transparent electrodes combining ITO electrodes or ITO electrodes and conductive polymer layers are superior to metal electrodes such as Au in transparency but have inferior electrical performance. Has been.

As a specific application, for example, in an organic solar cell, even if a combination of materials that can achieve high performance theoretically or empirically is selected for a semiconductor layer, the current value and photoelectric conversion efficiency are as expected. Performance may not be achieved. When various causes were examined, it was considered that the electrical performance between the semiconductor layer and the transparent electrode was not sufficient.
An object of the present invention is to improve the material and structure of a transparent electrode in a semiconductor device such as an organic solar cell as described above, and to improve performance as compared with a semiconductor device using a conventional transparent electrode. In particular, in various types of solar cells, it is to achieve an improvement in current value and photoelectric conversion efficiency that are limited only by material selection of semiconductor layers and electrode layers.

A light transmissive electrode for a semiconductor device according to the present invention is a light transmissive electrode disposed adjacent to a semiconductor layer in a semiconductor device, the fine particle conductive layer disposed adjacent to the semiconductor layer, and An organic material layer disposed adjacent to the particulate conductive layer, and a transparent conductive layer disposed adjacent to the organic material layer ,
The fine particle conductive layer is a fine particle conductive layer made of a conductive metal selected from the group consisting of In, Ag, Au, Al, Ca, Mg and LiF or a conductive metal compound thereof,
The organic material layer is a conductive polymer layer made of a conductive polymer selected from the group consisting of PEDOT: PSS [polyethylenedioxythiophene: polystyrene sulfonic acid], polyaniline, polythiophene, polypyrrole and poly (p-phenylene vinylene). ,
The transparent conductive layer, ITO (indium tin oxide), FTO Ru (fluorine-doped tin oxide) and ZnO transparent conductive layer der made of a conductive material selected from the group consisting of (zinc oxide).
[Semiconductor device]
Other structures are not particularly limited as long as the semiconductor device includes at least a part of a light-transmitting electrode.
A semiconductor device basically has a semiconductor layer sandwiched between a pair of electrodes. The target function is exhibited by the material and structure of the semiconductor layer and the electrical interaction between the semiconductor layer and the electrode adjacent to the semiconductor layer.

A specific example of the semiconductor device is a solar cell. A solar cell generates an electromotive force by a photoelectric conversion action between a semiconductor or a semiconductor and an electrode. An electrode having optical transparency is used at least for the electrode on which light is incident. There is an organic solar cell using an organic semiconductor material for a semiconductor layer. As the solar cell, a Schottky solar cell, a PIN solar cell, a PN solar cell, or the like is known depending on the photoelectric conversion effect. The difference in photoelectric conversion effect is caused by the combination of materials and structures of the semiconductor layer and the electrode layer.
There is an EL element as a semiconductor device. The EL element has a semiconductor layer that emits light when an electric current flows. A light transmissive electrode is used on the side from which light is emitted to the outside.

As a semiconductor device, there is a stacked type semiconductor device (referred to as a stack structure or a tandem structure) in which a plurality of structural units each including a semiconductor layer and an electrode layer and performing basic functions are stacked. In this case, a plurality of electrodes including one side and the intermediate layer arranged at a position where light passes are formed of light transmissive electrodes.
The light transmissive electrode includes a particulate conductive layer, an organic material layer, and a transparent conductive layer. Each layer will be described in the order of production in a normal manufacturing process.
[Transparent conductive layer]
Basically, the material and structure of the transparent conductive layer used for the light transmissive electrode in a normal solar cell can be applied.

Examples of highly transparent conductive materials include ITO (indium tin oxide), FTO (fluorine-doped tin oxide), and ZnO (zinc oxide). Many of these materials have a relatively large work function. For example, ITO and FTO have a large work function.
Even a layer made of a normal conductive metal can be used as a transparent conductive layer by showing substantially sufficient transparency if its thickness is reduced.
The light transmittance of the transparent conductive layer is desirably 50 to 100%.
Usually, the surface of a transparent conductive layer formed on a substrate such as glass or resin often has a relatively large uneven surface. For example, a conductive material deposited on a substrate by a thin film formation technique such as a vapor deposition method has a structure in which conductive material particles are integrated and integrated. It is easy to form on the surface. Depending on the manufacturing conditions, it is also possible to obtain a product with relatively few surface irregularities.

[Organic material layer]
It arrange | positions adjacent to a transparent conductive layer. The transparent conductive layer and the semiconductor layer are physically separated. For example, it functions to reliably configure an electrical barrier between the semiconductor layer and the transparent conductive layer. Even if there are large irregularities on the surface of the transparent conductive layer, it fills the irregularities and flattens the arrangement surface of the particulate conductive layer, or covers the surface of the transparent conductive layer with certainty. can do.
As an organic material, it is only necessary to achieve such a basic function. Conductive polymers used in various electronic circuit technologies can be used. An insulating polymer can also be used if it is sufficiently thin. If the organic material is made of a soluble material, it can be applied to the surface of the transparent conductive layer to reliably cover the entire surface without any gaps. It is also easy to fill the unevenness by pouring into the uneven surface of the transparent conductive layer. In the case where the organic material layer is disposed between paths until light reaches the semiconductor layer, a material having excellent transparency is preferable.

Specific examples of the conductive polymer include PEDOT: PSS [polyethylenedioxythiophene: polystyrenesulfonic acid], polyaniline, polythiophene, polypyrrole, poly (p-phenylene vinylene), and the like.
The thickness of the organic material layer is set so that the transparent conductive layer and the semiconductor layer can be reliably separated. Moreover, the thickness which can substantially fill the unevenness | corrugation of a transparent conductive layer can be provided. When a liquid film of a soluble material is formed on the uneven surface of the transparent conductive layer, the liquid film or the liquid film is placed so that the liquid film fills the uneven surface of the transparent conductive layer and the surface of the liquid film becomes flat. The thickness of the organic material layer to be cured can be set.

  The surface of the organic material layer disposed adjacent to the transparent conductive layer can be made substantially flat. “Substantially flat” does not have to be a strict plane in a mathematical sense. The particulate conductive layer arranged adjacent to the organic material layer is not flatly buried in the irregularities on the surface of the organic material layer, but is made flat enough to be arranged side by side on the surface. be able to. It is flat at the stage of forming the organic material layer, but when the fine particle conductive layer is formed thereon, a part of the conductive fine particles constituting the fine particle conductive layer is embedded in the organic material layer, and the organic material layer Slight irregularities may be formed on the surface of the film. Irregularities corresponding to the surface irregularities of the transparent conductive layer may remain on the surface of the organic material layer. If the surface of the transparent conductive layer is relatively flat, the surface of the organic material layer is also likely to be flat.

The thickness of the organic material layer may vary depending on the location in the plane direction depending on the uneven structure and depth of the transparent conductive layer, but the overall average thickness is 500 nm or less, preferably 5 to 100 nm, more preferably 10 It can be set to ˜80 nm. When the thickness of the organic material layer is in an appropriate range, the current-carrying performance between the fine particle conductive layer and the collector electrode layer is not hindered, and short circuit between the semiconductor layer and the collector electrode layer is prevented, so Can constitute a dynamic barrier.
The light transmittance of the organic material layer is desirably 50 to 100%.
[Fine particle conductive layer]
Located adjacent to the organic material layer.

Basically, the material, structure, and manufacturing technology of the fine-particle conductive layer used in ordinary solar cells and other electronic product technologies can be applied.
Examples of the material for the particulate conductive layer include conductive metals such as In, Ag, Au, Al, Ca, Mg, and LiF, metal compounds, and other conductive materials. If a material having a small work function is used as the conductive material constituting the fine particle conductive layer, the work function on the side adjacent to the semiconductor layer of the light transmissive electrode can be obtained even if a transparent conductive layer having a large work function is used. Can be small. Examples of materials having a small work function include Ca, In, Mg, Al, and LiF.

These conductive materials are deposited in the form of conductive fine particles to form a fine particle conductive layer. For example, the conductive metal material is formed into a film by thin film forming means such as a vapor deposition method, whereby the conductive fine particle deposition structure as described above can be obtained.
The smaller the particle size of the conductive fine particles constituting the fine particle conductive layer, the larger the contact area with the semiconductor layer, which is effective in improving the performance of the semiconductor device. Although it is also limited by the preparation conditions of the fine particle conductive layer, it is usually set to an average particle size of 100 nm or less, preferably 20 nm or less, more preferably 1 to 10 nm.
The conductive fine particles may be arranged in a close-packed structure in the plane direction, but are usually arranged randomly. The conductive fine particles are arranged in close contact with each other or are arranged with a gap. Even if they are arranged in a close-packed structure, gaps are formed between the particles depending on the particle shape.

In the fine particle conductive layer, the conductive fine particles may be deposited as a single layer or may be deposited as a multilayer. The fine particle conductive layer may be thin as long as the function of increasing the contact area with the semiconductor layer can be achieved. The thinner, the better the light transmission. Usually, the thickness of the particulate conductive layer is set to 100 nm or less, preferably 50 nm or less, more preferably 3 to 20 nm.
The particles constituting the fine particle conductive layer may be in a state where a part of each particle is embedded from the surface of the organic material layer. When a part of the particles is embedded in the organic material layer and the other part is embedded in the semiconductor layer, the contact area with both the organic material layer and the semiconductor layer can be increased.

[Semiconductor layer]
It is arranged adjacent to the fine particle conductive layer. It is a basic structure that functions as a semiconductor device. For example, in a solar cell, an electromotive force is generated.
Depending on the purpose and function of the semiconductor device, the same material, structure, or manufacturing technique as that of a normal semiconductor device can be applied.
Semiconductors are usually divided into p-type semiconductors, n-type semiconductors, and i-type semiconductors (also referred to as intrinsic semiconductors) depending on the constituent elements, molecular structures, doping materials, and the like. A semiconductor layer can be formed.

[Other electrodes]
An electrode of a semiconductor device may be configured only by a light transmissive electrode, or may be configured by combining a light transmissive electrode and a normal electrode having no light transmissive property.
Usually, a light transmissive electrode is disposed on one side of the semiconductor layer, and a second electrode having no light transmissive property is disposed on the opposite side. However, in a semiconductor device having a stack structure in which the unit structures of the semiconductor device are stacked, a light-transmitting electrode may be disposed as an intermediate layer electrode. In this case, light transmissive electrodes are disposed on both sides of the semiconductor layer.
As an electrode that does not have optical transparency, ordinary electrode materials and structures can be employed. For example, conductive metal materials such as Au, Ag, Al, In, Mg, and Ca are used. In addition, even if these conductive metals are made thin, they will show substantially sufficient transparency and may be used for the transparent conductive layer of a light transmissive electrode.

[Manufacture of semiconductor devices]
A method of manufacturing a semiconductor device including the above-described light transmissive electrode according to the present invention, and basically, manufacturing techniques such as a normal semiconductor device manufacturing apparatus and manufacturing conditions can be applied.
The basic manufacturing process includes the following steps.
Preparing the transparent conductive layer (a);
(B) forming a liquid film containing a soluble material constituting the organic material layer on the transparent conductive layer and curing it to form an organic material layer having a substantially flat surface.
A step (c) of forming a particulate conductive layer on the organic material layer;
Forming the semiconductor layer on the particulate conductive layer (d);

A second electrode is usually formed on the semiconductor layer. Furthermore, a semiconductor layer and an electrode can be stacked by a plurality of units.
In the step (a), a conductive transparent substrate formed by forming a thin film of a conductive material, that is, a transparent conductive layer, on the surface of a transparent substrate made of transparent glass or transparent resin is usually used. Such a conductive transparent substrate can also be obtained as a commercial product.
In the step (b), a soluble material, which is an organic material constituting the organic material layer, is dissolved or dispersed in a solvent such as water, an organic solvent, or an inorganic solvent, so that a liquid film can be formed.
The liquid film can be formed by means suitable for forming a thin liquid film such as spin coating. Ensure that the liquid film covers the entire surface of the transparent conductive layer. It is desirable that the liquid film sufficiently fills up the irregularities present on the surface of the transparent conductive layer and that the surface of the liquid film be flat. After forming a liquid film, curing is performed after a certain period of time, or pressure or vibration is applied to the liquid film to promote filling the surface irregularities of the transparent conductive layer or flattening the surface. Can do. For curing the liquid film, means such as drying, heat curing, and radiation curing can be employed.

The step (c) can be performed after the organic material layer is completely cured, or can be performed before the organic material layer is completely cured. For the formation of the fine particle conductive layer, a fine particle deposition technique such as a vacuum evaporation method can be used. By adjusting the acceleration energy of the particles among the formation conditions of the fine particle conductive layer, the particles constituting the fine particle conductive layer can be prevented from being completely embedded inside the organic material layer. desirable.
For the step (d), a technique for forming a semiconductor layer in a normal semiconductor device can be applied. A thin film forming means such as vapor deposition is employed in accordance with the constituent material of the semiconductor layer. If it is an organic material, spin coating or the like can be employed.

In the case where the material layer constituting the semiconductor device is present in addition to the above layers, formation means suitable for each layer material can be combined.
[Specific structure of semiconductor layer]
As a specific configuration of the semiconductor layer, the following layer structure can be adopted.
<Schottky solar cell>
The semiconductor layer disposed adjacent to the light transmissive electrode is formed of a p-type semiconductor layer that forms a Schottky barrier with the light transmissive electrode.
<PIN solar cell>
The semiconductor layer disposed adjacent to the light transmissive electrode is disposed in the order of the n-type semiconductor layer, the i-type (intrinsic) semiconductor layer, and the p-type semiconductor layer from the side near the light transmissive electrode. The n-type semiconductor layer and the light transmissive electrode make ohmic contact.

<PN type solar cell>
The semiconductor layer disposed adjacent to the light transmissive electrode is disposed in the order of the n-type semiconductor layer and the p-type semiconductor layer from the side close to the light transmissive electrode. Also in this case, the n-type semiconductor layer and the light transmitting electrode make ohmic contact.
<Organic EL device>
The semiconductor layer disposed adjacent to the light transmissive electrode is disposed in the order of the n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer from the side close to the light transmissive electrode. Also in this case, the n-type semiconductor layer and the light transmitting electrode make ohmic contact. However, when the n-type semiconductor layer or the p-type semiconductor layer also serves as the light emitting layer, the light emitting layer may not be provided separately.

The light transmissive electrode according to the present invention can improve electrical performance by combining a transparent conductive layer and an organic material layer, and further includes a fine particle conductive layer, thereby forming a fine particle conductive layer. The entire surface of each conductive fine particle can be in contact with the semiconductor layer, and the contact interface between the light transmissive electrode and the adjacent semiconductor layer can be greatly increased.
In addition, since the particulate conductive layer is in direct contact with the semiconductor layer, the electrical characteristics at the contact interface with the semiconductor layer can be changed by selecting the material for the particulate conductive layer appropriately. It can be changed to a property that is difficult to achieve with only the material of the material layer. For example, even if a material having a high work function is used for the transparent conductive layer, if a material having a low work function is used for the material of the fine particle conductive layer, the transparent conductive layer functions as a material having a low work function on one side of the light-transmitting electrode. be able to. When semiconductor layers are arranged on both sides of the light transmissive electrode, one surface of the light transmissive electrode functions as an electrode having a high work function, and the opposite surface of the light transmissive electrode functions as an electrode having a small work function. It will be.

  In addition, when the fine particle conductive layer is formed directly on the transparent conductive layer, the transparent conductive layer and the semiconductor layer are in direct contact with each other through a gap generated between the conductive fine particles constituting the fine particle conductive layer. However, if the organic material layer is present, the semiconductor layer is not in direct contact with the transparent conductive layer. The improvement of the above characteristics due to the fine particle conductive layer is satisfactorily exhibited. It can be reliably prevented that the semiconductor layer and the transparent conductive layer are short-circuited or the electrical barrier is lost. Even if the surface of the transparent conductive layer has large unevenness, the surface unevenness of the transparent conductive layer can be filled with the organic material layer. If the fine particle conductive layer is arranged on the surface of the organic material layer with few unevenness obtained in this way, the fine particle conductive layer does not fall into the large unevenness of the transparent conductive layer. By interposing the organic material layer between them, the electrical contact between the transparent conductive layer and the particulate conductive layer is good.

  As a result, it becomes possible to efficiently achieve the performance improvement of the semiconductor device using the light transmissive electrode including the solar cell.

[Schottky type solar cell]
FIG. 1 shows a schematic structure of a Schottky solar cell as a semiconductor device according to an embodiment of the present invention.
The solar cell has a structure in which a transparent conductive layer 10, an organic material layer 20, a particulate conductive layer 30, a semiconductor layer 40, and a second electrode layer 50 are sequentially stacked. A current is taken out from the wirings 60 and 60 connected to the transparent conductive layer 10 and the second electrode layer 50 at both ends.
The transparent conductive layer 10 disposed on the lower side of the figure is made of an ITO layer. ITO is a material having a large work function. Although not shown, an ITO layer is formed by forming an ITO film on the surface of a glass substrate or a PET resin sheet. A wiring 60 connected to an external circuit is connected to the transparent conductive layer 10. As shown in FIG. 2, large irregularities or undulations are generated on the surface of the transparent conductive layer 10 made of an ITO layer. This is caused by the properties of ITO material and the manufacturing method.

The organic material layer 20 is composed of a PEDOT: PSS layer. A solution containing PEDOT: PSS can be formed by spin-coating on the transparent conductive layer 10 and then drying and curing. As shown in FIG. 2, one side of the organic material layer 20 has a curved surface shape along large irregularities or undulations on the surface of the transparent conductive layer 10. The opposite surface of the organic material layer 20 is a substantially flat surface. Therefore, the thickness of the organic material layer 20 varies depending on the location in the plane direction. The entire surface of the transparent conductive layer 10 is covered with the organic material layer 20, and the transparent conductive layer 10 is not exposed at all on the surface side of the organic material layer 20.
As shown in FIG. 2, the fine particle conductive layer 30 is in a state where conductive fine particles 32 made of In metal, which are schematically represented in a spherical shape, are randomly deposited. In is a material having a small work function. The conductive fine particles 32 are arranged side by side on the surface of the organic material layer 20. The conductive fine particles 32 do not come into contact with the transparent conductive layer 10 below the organic material layer 20. The interval between the conductive fine particles 32 is not constant. There are places where the conductive fine particles 32 are in close contact with each other and where there is a gap. In the drawing, the conductive fine particles 32 are displayed in a state of being arranged in a single layer. However, in reality, the conductive fine particles 32 may be multilayered or the conductive fine particles 32 may partially overlap.

The semiconductor layer 40 is made of a p-type semiconductor material such as ZnPc. The fine particle conductive layer 30 is completely covered. In the fine particle conductive layer 30, there is a portion where the material of the semiconductor layer 40 directly reaches the surface of the organic material layer 20 at a gap portion between the conductive fine particles 32. However, the semiconductor layer 40 does not directly contact the transparent conductive layer 10.
The upper second electrode layer 50 is made of an Au layer. As shown in FIG. 1, a wiring 60 is connected to the second electrode layer 50.
In FIG. 1, light hits from the direction indicated by the white arrow, and light incident from the lower transparent conductive layer 10 side reaches the semiconductor layer 40 and causes a photoelectric conversion action. A current is efficiently generated between the transparent conductive layer 10 and the second electrode 50 at both ends by the action of the Schottky barrier formed between the semiconductor layer 40 and the fine particle conductive layer 30 having a small work function.

At this time, since the semiconductor layer 40 and the fine particle conductive layer 30 are in contact with each other with a large contact area corresponding to the three-dimensional surface area of the conductive fine particles 32, the electrical contact performance between them is extremely good. There is a large electromotive force or current. Since the particulate conductive layer 30 has good electrical contact with the transparent conductive layer 10 via the organic material layer 20 made of a conductive polymer, the generated electromotive force or current can be efficiently transferred to the transparent conductive layer 10. To the wiring 60 can be taken out.
Furthermore, even if there is a part of the semiconductor layer 40 that enters the gap between the conductive fine particles 32 in the fine particle conductive layer 30, the organic material layer 20 exists between the transparent conductive layer 10. Therefore, it is reliably prevented that the semiconductor layer 40 is directly short-circuited with the transparent conductive layer 10 and the electrical barrier is lost.

As a result, performance such as a current value and photoelectric conversion efficiency generated in the Schottky battery is remarkably improved.
[PIN solar cell]
FIG. 3 shows a schematic structure of a PIN solar cell according to another embodiment. Since the basic structure is the same as that of the Schottky battery, different structures will be mainly described.
A transparent conductive layer 10 made of an ITO layer, an organic material layer 20 made of a PEDOT: PSS layer, a particulate conductive layer 30 made of In, a semiconductor layer 40, and a second electrode layer 50 made of Au are sequentially laminated. A current is taken out from the wirings 60 and 60 connected to the transparent conductive layer 10 and the second electrode layer 50 at both ends. The basic structure so far is common to the above embodiment.

In the PIN type battery, the semiconductor layer 40 includes three layers of an n-type semiconductor layer 42, an i-type semiconductor layer 44, and a p-type semiconductor layer 46 in order from the particulate conductive layer 30 side. As a specific example, the n-type semiconductor layer 42 can be composed of a C60 layer, the i-type semiconductor layer 44 can be composed of a C60: ZnPc layer, and the p-type semiconductor layer 46 can be composed of a ZnPc layer.
The detailed structure around the organic material layer 20 has the same structure as FIG. 2 in the above embodiment.
In such a PIN battery, light is applied from the direction indicated by the white arrow in FIG. Light incident from the lower transparent conductive layer 10 side reaches the semiconductor layer 40 and causes a photoelectric conversion action in the PIN type semiconductor structure. A current is efficiently generated between the transparent conductive layer 10 and the second electrode layer 50 at both ends.

Similarly to the above, the presence of the organic material layer 20 effectively increases the electrical contact area between the semiconductor layer 40 and the particulate conductive layer 30, or the transparent conductive layer from the particulate conductive layer 30 through the organic material layer 20. The electrical resistance up to 10 can be reduced, or the semiconductor layer 40 and the transparent conductive layer 10 can be prevented from being short-circuited.
As a result, the performance of the PIN type battery is also greatly improved.

The solar cell used as embodiment of this invention was manufactured, and the performance was evaluated.
[Manufacture of Schottky solar cells]
Solar cells having the layer structure shown in Table 1 were manufactured. The specific manufacturing procedure is as follows.
<Examples 10 and 11>
A commercially available ITO substrate (I) [manufactured by Geomatek Co.] was prepared. An ITO layer serving as a transparent electrode layer is formed on the surface of the glass substrate.
On the ITO layer of the ITO substrate (I), PEDOT: PSS (hereinafter abbreviated as PEDOT) (manufactured by Bayern, 4083 grade) is used, and the PEDOT film is spin-coated by a conventional method (processing conditions: 5000 rpm). 5 seconds later, 3000 rpm, 180 seconds). After film formation, the film was dried at 100 ° C. for 10 minutes or more to completely remove moisture. This is because the PEDOT material contains moisture, and it is difficult to exhibit sufficient performance if moisture is contained in the PEDOT film.

On the PEDOT film, an In layer, a ZnPc layer, and an Au layer were deposited in this order.
ZnPc is zinc phthalocyanine.
<Comparative Examples 10-12>
Based on the manufacturing procedures of Examples 10 and 11, some layers were omitted or another material was used.
[Performance evaluation test]
The produced solar cell was subjected to the following test.
A device (manufactured by Kansai Scientific Machinery Co., Ltd.) for obtaining simulated sunlight by passing light irradiated from a 500 W xenon lamp (manufactured by Ushio Inc.) through a spectral filter (manufactured by Oriel, AM1.5) was used. The intensity of the simulated sunlight was 100 mW / cm ² .

With respect to a solar cell having a photoelectric conversion area of 0.04 cm ² , an alligator clip was connected to the wiring connected to each collector electrode, and the generated electricity was measured with a current-voltage measuring device used for performance evaluation of the solar cell. The measuring device includes an ammeter, a function generator, a potentio stud, and the like.
Short-circuit photocurrent density (Isc), open-circuit photovoltage (Voc), fill factor (f.f.), etc. were measured, and energy conversion efficiency (η) was calculated from these values using the following equation.
Fill factor (f.f.) =
[Maximum electromotive force of solar cell] / (Voc × Isc) (1)
Here, the maximum electromotive force of the solar cell is
[Maximum electromotive force of solar cell] = [maximum value of (current value × voltage value)].

Energy conversion efficiency η (%) =
Voc × Isc × f. f. / 100 (mW / cm ² ) × 100 (2)
The test results are shown in Table 1.
〔Measurement result〕

<Evaluation>
(1) In Comparative Example 10, the In layer exists between the ITO layer and the ZnPc layer but does not have the PEDOT layer. Therefore, a short circuit occurs and the function as a solar cell cannot be exhibited at all.
On the other hand, in each embodiment, both the In layer and the PEDOT layer are provided between the ITO layer and the ZnPc layer. As a result, a good current value (Isc) and voltage (Voc) are obtained.
(2) As in Comparative Example 11, even when only the PEDOT layer is provided without providing the In layer, the function as a solar cell cannot be exhibited. If there is no In layer, the battery function due to the Schottky barrier does not occur.

(3) As shown in Comparative Example 12, a Schottky solar cell can also be configured with an ITO / ZnPc / Al structure. In this case, a Schottky barrier is formed between Al and ZnPc. However, the performance is clearly inferior to the examples.
(4) In Non-Patent Document 1 described in the section of the background art, the current value = 3.5 × 10 ⁻⁴ mA / cm ² , voltage = about the performance of the Au / ZnPc / Al structure Schottky solar cell. 0.59V, fill factor f. f. = 0.1, energy conversion efficiency η = 3 × 10 ⁻⁴ % (light intensity 0.1 mW / cm ² ) is described.
Each example has a much higher current value and energy conversion efficiency than the Schottky battery of Non-Patent Document 1, and has a high practical value.

[In layer thickness and performance evaluation]
In the Schottky solar cell of Example 10, the same test was performed by changing the thickness of the In layer in various ways. The production conditions were the same as in Example 10 except for the thickness of the In layer. The form of fine particles in the In layer was confirmed by observation with a transmission electron microscope.
FIG. 4 is a graph showing the energy conversion efficiency η of the obtained solar cell. In the graph, black dots indicate measured values, and thin lines extending above and below some black dots indicate measurement variation ranges. A thick line is a correlation curve estimated from measurement data.
From the result of FIG. 4, it can be seen that the highest performance can be exhibited when the thickness of the In layer is around 5 to 6 nm.

When the thickness of the In layer is 0, the light-transmitting electrode is an electrode having a large work function made of ITO / PEDOT, so that no Schottky barrier is formed and the solar cell does not function. If the thickness of the In layer is close to 15 nm, a fine particle structure cannot be formed, resulting in a flat layer. In this case, the contact area is reduced, and the energy conversion efficiency is reduced. In the vicinity of the In layer thickness of 5 nm, a fine particle structure with the largest contact area is obtained, and the conversion efficiency is also high. At this time, the average particle diameter of the In fine particles was about 10 to 20 nm, and the individual fine particles were in a single crystal state.
[Manufacture of PIN solar cells]
A PIN-type battery was fabricated using a technique that is basically the same as that of the above-described embodiment, and its performance was evaluated.

In Example 10, materials and processing steps common to Example 10 were adopted except that the structure of the semiconductor layer and the manufacturing process were partially changed.
C60 is fullerene-C60, and a film was formed by vapor deposition.
For C60: ZnPc, a mixed layer of C60 and ZnPc in a volume ratio of 1: 1 was formed by vacuum co-evaporation.
[Performance evaluation]
The same performance evaluation test as that of the Schottky solar cell was performed, and the results are shown in Tables 2 and 3.

<Evaluation>
(1) It has been demonstrated that a good current value (Isc) and voltage (Voc) can be obtained by combining the In layer and the PEDOT layer even in a PIN type battery.
(2) In Comparative Example 20 having no In layer and PEDOT layer, a solar cell cannot be formed. This is because the ITO layer having a large work function is adjacent to the n-type C60 layer among the semiconductor layers.
(3) As in Comparative Example 21, if an Al layer is used as the electrode on the n-type C60 layer side of the semiconductor layer and the ITO layer is used as the electrode on the p-type ZnPc layer side, the PEDOT layer Even without the In layer, a PIN battery can be constructed.

However, in Example 20, the current value is larger, the fill factor, and the photoelectric conversion efficiency are higher in Example 20. As for the voltage, Comparative Example 21 is slightly higher, but Example 20 can generate a practically sufficient voltage.
In Comparative Example 21, an Al electrode that is chemically unstable and easily deteriorated is used as an electrode facing the ITO electrode, whereas in Example 20, an Au electrode that is chemically stable and hardly deteriorated is used. Therefore, there is an advantage that the deterioration of performance of the solar cell with time is reduced.
[Manufacture of PN battery]
A PN-type battery was fabricated by using a technique that is basically the same as that of the above example, and its performance was evaluated.

Basically, in Example 20, the materials and processing steps common to Example 20 were performed, except that the structure of the semiconductor layer and the manufacturing process were partially changed.
The PEDOT layer adjacent to the ITO layer was formed by spin coating (processing conditions: 8000 rpm, 120 sec). Thereafter, the film was dried at a vacuum degree of 3 × 10 ⁻⁵ torr and 100 ° C. for 5 minutes, and the temperature was lowered to 50 ° C. or less over 45 minutes.
PV layer is bisbenzimidazo [2,1-a: 1 ′, 2′-b ′] ancera [2,1,9-def: 6,5,10-d′e′f ′] diisoquinoline-6 , 11-dione] and constitutes an n-type semiconductor layer. It was formed by vapor deposition.

The PA-PPV layer is poly (phenylimino-1,4-phenylene-1,2-ethynylene-2,5-dihexyloxy-1,4-phenylene-1,2-ethynylene-1,4-phenylene), A p-type semiconductor layer is formed. It was formed by spin coating in the same manner as the PEDOT layer.
The PEDOT layer formed on the PA-PPV layer was also produced by spin coating similar to the above. The PEDOT layer on this side is not combined with an In layer, but has a function of improving electrical contact between the PA-PPV layer and the Au layer.
[Performance evaluation]
The same performance evaluation test as in the above example was performed, and the results are shown in Table 4.

<Evaluation>
(1) It was demonstrated that a good current value (Isc) and voltage (Voc) can be obtained by providing an In layer and a PEDOT layer in a PN type battery.

  The solar cell of the present invention can efficiently convert sunlight into electric power, and is useful as a power source or an auxiliary power source in various mobile devices, buildings, and other various device devices.

Schematic cross-sectional structure diagram of a Schottky solar cell representing an embodiment of the present invention Expanded schematic structure diagram around the organic material layer Schematic cross-sectional structure of PIN type solar cell Relationship diagram between In layer thickness and conversion efficiency in Schottky solar cells

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transparent conductive layer 20 Organic material layer 30 Particulate conductive layer 32 Conductive fine particle 40 Semiconductor layer 42 N-type semiconductor layer 44 i-type semiconductor layer 46 p-type semiconductor layer 50 2nd electrode

Claims (10)

An electrode that is disposed adjacent to a semiconductor layer in a semiconductor device and has optical transparency,
A particulate conductive layer disposed adjacent to the semiconductor layer;
An organic material layer disposed adjacent to the particulate conductive layer;
A transparent conductive layer disposed adjacent to the organic material layer;
Equipped with a,
The fine particle conductive layer is a fine particle conductive layer made of a conductive metal selected from the group consisting of In, Ag, Au, Al, Ca, Mg and LiF or a conductive metal compound thereof,
The organic material layer is a conductive polymer layer made of a conductive polymer selected from the group consisting of PEDOT: PSS [polyethylenedioxythiophene: polystyrene sulfonic acid], polyaniline, polythiophene, polypyrrole and poly (p-phenylene vinylene). ,
The transparent conductive layer, ITO (indium tin oxide), FTO (fluorine-doped tin oxide) and ZnO Ru transparent conductive layer der made of a conductive material selected from the group consisting of (zinc oxide), light transmission for a semiconductor device Sex electrode.   The light transmissive electrode according to claim 1, wherein the fine particle conductive layer is made of conductive fine particles, and the conductive fine particles are made of a conductive metal.   The light transmissive electrode according to claim 1, wherein the fine particle conductive layer is formed by depositing conductive fine particles as a single layer. The boundary surface between the organic material layer and the transparent conductive layer is an uneven surface ,
Interface between the pre-Symbol organic material layer and the particulate conductive layer is substantially flat,
The average thickness of the organic material layer is 10 to 80 nm.
The light transmissive electrode according to claim 1. The conductive fine particles have an average particle size of 1 to 10 nm,
The fine particle conductive layer has a thickness of 3 to 20 nm.
The light transmissive electrode according to claim 2. A first electrode comprising the light transmissive electrode according to any one of claims 1 to 5;
A semiconductor layer disposed adjacent to the first electrode;
A second electrode disposed adjacent to the opposite side of the first electrode of the semiconductor layer;
A semiconductor device comprising: The semiconductor device according to claim 6,
The semiconductor layer includes an organic semiconductor layer;
It is an organic solar cell that generates an electromotive force by light incident from the first electrode side.
Semiconductor device. A semiconductor device according to claim 6 or 7, wherein
The organic semiconductor layer is a Schottky type organic solar cell comprising a p-type semiconductor layer constituting a Schottky barrier between the first electrode and the organic semiconductor layer.
Semiconductor device. A semiconductor device according to claim 6 or 7, wherein
The organic semiconductor layer is an ohmic contact type organic solar cell in ohmic contact with the first electrode,
Semiconductor device. A method for manufacturing a semiconductor device comprising the light transmissive electrode according to claim 1,
Preparing the transparent conductive layer (a);
(B) forming a liquid film containing a soluble material constituting the organic material layer on the transparent conductive layer and curing it to form an organic material layer having a substantially flat surface;
A step (c) of forming a particulate conductive layer on the organic material layer;
Forming the semiconductor layer on the particulate conductive layer (d);
A method for manufacturing a semiconductor device, comprising:

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