JPH03285366A - Solar cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to solar cells using organic materials. Conventional technology Compared to inorganic/recon solar cells, organic solar cells have the following characteristics: they are able to synthesize materials with high sensitivity to various wavelengths through molecular design, are superior in productivity and economy, and are inexpensive. active research and development is currently underway. However, its performance: well, it is far inferior to silicon solar cells, and there are currently no commercially available solar cells. The characteristics of solar cells are usually the voltage when the current becomes O (
Open #A lightning voltage (abbreviated as VOC), photocurrent when applied voltage is 0 (short-circuit photocurrent, abbreviated as 1.), maximum power and ISC
and vo. ratio (abbreviated as fill factor FF), conversion efficiency (η= (VocX l5cXF F) /Pi*
X 100, expressed as a percentage). Organic solar cells are generally evaluated and researched as Schottky barrier type photoelectric conversion elements. The figure shows the structure of a Schottky-type photoelectric conversion element. Inch, and light is irradiated from the barrier electrode side. In the figure, 4 is a substrate. Organic materials that have been studied as materials for such devices include tetracene, merocyanine, polyacetylene, polyparaphenylene sulfide (PPS), and nickel phthalocyanine (NiPc). These are converted into 3H by a vapor deposition method or a polymerization method to form a device. X of metal-free phthalocyanine (hereinafter abbreviated as H2-Pc)
type and α type are made into thin films as polymer dispersion systems and made into devices. Metals considered as barrier electrodes include aluminum, indium, etc., and ohmic electrodes include gold, silver, copper, tin oxide, tin, indium oxide, etc. However, the characteristics of solar cells produced using these materials are inferior to those of inorganic silicon solar cells. For example, AI/tetracene/
■ Large BH pond formed by Ag. . , l3. , FF and η are 0.65V, 0.06μA, respectively.
CI-'', 0.55.10-'%, and A
0.5V for I/PPS/Cu, 0.
0018 μA, cya-”, 0.28.0.21%,
For AI/NiPc/NESA, 0.68V O,0
42uA, crn-”, 0.32.0.]2%, AI
/X-H! Pc, 0.86 for PVAc/5nOz
V, 1.4 μA, cm-”, 6.5%, In/X
HzPc, Pc/NESA: 0.4V, 179μ
A, cm-”2.4%, AI/α-H2PC, PVDF
/IntO3: 0.92V, 8.7μA, cta
-", 1.4%, and all of them had insufficient characteristics from a practical point of view. Problems to be Solved by the Invention The problems to be solved by this invention are to solve the above-mentioned problems of conventional organic solar cells. The purpose is to eliminate the drawbacks such as , and to promote high performance and durable solar cells.In particular, we will focus on H, -Pc, which has been most studied as an electromotive force material for solar cells. We are trying to improve the performance by creating a photovoltaic layer with an unprecedented structure using We investigated an organic solar cell with the following configuration.As a result, we found that
! -Pc or τ-type H, -Pc and various metal phthalocyanines (hereinafter abbreviated as metal Pc) are treated with an appropriate solvent to form molecularly dispersed H in a binder polymer.
2-PC and particulate dispersed H, -Pc and metal Pc
The present invention was completed by discovering that a solar cell having a photovoltaic layer consisting of a combination of the following exhibits excellent electromotive force characteristics. That is, the present invention provides H, -Pc molecularly dispersed in a Hi-7D polymer and a binder polymer, and X-type HzPc and/or

The main feature of the solar cell is a photovoltaic layer consisting of Hz-Pc and metal Pc dispersed in particle form in a binder polymer, and its characteristics are
Two types of 2-Pc and H-Pc dispersed in particulate form coexist with metal Pc dispersed in particulate form. Function: The solar cell according to the present invention has the following features. ■ Since HtPc with a new crystal structure is used,
Compared to conventional solar cells, it has much higher performance and
Shows excellent properties over a wide wavelength range of ~800 nm. For example, a new H2-P made from X-type Hz-Pc, PbPc, and polyvinyl butyral (weight ratio 1:2:1)
The solar cell of the present invention has a photovoltaic layer containing c, and this photovoltaic layer is configured with AI as a blocking electrode and Ag as an ohmic electrode. c, Isc, F
The values of F and η are 0.85V and 5.15, respectively.
μA, cm-”, 0.70.8.2%, which is much higher performance than conventional organic solar cells. ■ Since the photovoltaic layer has a single-layer structure, the manufacturing process is simple. In addition, it has superior stability compared to conventional single-layer structure solar cells.The present invention will be explained in detail below with examples. Two types of particulate dispersed Hz Pc coexist with particulate dispersed metal Pc. Regarding Ht-Pc, Xerox has developed X-type H,-Pc, which has excellent electrophotographic properties. Development method 15P 3,357,989), its synthesis method, relationship between crystal type and electrophotographic properties, structural analysis, application to solar cells (R, O, Louutfy and J, H, 5 ha
rp, J., Chefl. Phys, 71, 1211 (1979), etc. X-type H2PC is β synthesized by a conventional method.
Type HtPc is converted into α type by treatment with sulfuric acid, and this is produced from C2 by ball milling for a long time. This crystal structure is clearly W different from the conventional α type and β type. According to its X-ray diffraction diagram (measured using CuKα radiation), the diffraction lines are 2θ=7.4.9.0, 15.1. ]6.517
．． 2.20.1.20.6.20.7.21.4.22
．． Appears at 2.23.8.27.2.28.530.3'. The most intense diffraction line: The diffraction line around 7.5° (corresponding to the interplanar spacing d = 11.8 people), and if its intensity is 1, the intensity of the diffraction line around 9.1° ( The surface distance d (equivalent to 9.8 people) is 0.66. This strength ratio is hardly affected by the grain size of the crystals. The absorption spectrum of the X-form H,-Pc is also clearly different from that of the α- and β-forms. This difference in spectra due to the difference in crystal type is due to the difference in the stacking state of the Hz Pc molecule in the crystal state, and it has been reported that the X-form H,-Pc has a dimeric structure. H,-Pc having other crystal forms includes τ type H7Pc. It is obtained by ball milling α, β, Its X-type diffraction pattern is essentially similar to that of X-type. However, in this case, the ratio of the diffraction line intensity around 7.5° and the diffraction line intensity around 9.1° is 1:0.8. Money W! APc includes various crystalline copper phthalocyanine (CuPc), lead phthalocyanine (PbPc), tin phthalonoanine (SnPc), and zinc phthalonoanine (Zn).
Pc), magnonium phthalocyanine (MgPc)-noriconphthalocyanine (SiPc), chloraluminum phthalonoanine (~'Pc), chloraluminum phthalo/anine (AICIPc), titanyl phthalo/anine (Ti
OPc), chloroindium phthalocyanine (InCI
Pc), chlorogallium phthalocyanine (GaC]Pc)
), etc., and at least one selected from these can be used. When producing the photovoltaic layer of the solar cell according to the present invention, X-type and/or τ-type H, -Pc and metal Pc are combined as starting materials, and these X-type or τ-type H, -Pc are combined. ,
The mixture is placed in a reaction vessel together with a solvent capable of dissolving at least a portion of it, metal Pc, and if necessary a binder polymer, and thoroughly stirred and mixed. Sufficient kneading is an important point when manufacturing the solar cell of the second invention. Generally, it takes one day or more to create such a stable kneading state using a normal stirring method. The X-ray phase diagram of the Shingu light body obtained by such a method using X-type or τ-type OH2Pc and metal Pc as starting materials is the combination of 11□-Pc and metal Yも(
1, H,-Pc changes the X-ray diffraction pattern due to solvent treatment. In particular, HH-Pc (7) 2θ-21, 4' or more, the O-stroke 1st line disappears (there is 22 in the ψ direction, and the diffraction line around 16.5°; it tends to increase. The most noticeable change is X-type) (75° (d=]], the most characteristic of 7Pc, 8 people)
, of the two C5 diffraction lines around 9.1° (d=9.8 people), only the diffraction line around 7.5° has selectively disappeared. Of course, the X-ray diffraction diagram of Shingu Light Body is of α type and β type.
It is also different from the X-ray diffraction diagram of type (7)H, -PC. The degree, time, temperature, etc. of the above-mentioned kneading to obtain Shingu Hikari vary depending on the solvent used and the type of polymer. In order to obtain the best characteristics as a solar cell, it is necessary to determine the appropriate degree of reaction, which is neither insufficient nor excessive in the treatment with the solvent. The diffraction line intensity ratio (1,,,1/1.1) between around 7.5° and around 9.1° of the X-ray diffraction pattern is 1 to 0.
．． It is sufficient to confirm that the value is between 0.02 and 0.02. In this invention, the metal Pc acts as a charge generating agent,
The molecularly dispersed H, -Pc acts as a charge transfer agent. Therefore, in this invention, the metal Pc is
It may be dispersed in particulate form, and does not necessarily need to be dispersed in molecular form. The absorption spectrum of the new photoreceptor produced by this method also shows X-type and τ-type H2-P.
It is clearly different from the absorption spectrum of c. In order to realize the state in which a part of Hz-Pc is molecularly dispersed in the polymer binder in this invention, it is necessary to use X-type or τ-type Hz-Pc in a suitable manner. 7 to [container]
It is preferable to select a polymer as the binder that is both soluble and soluble. Hz PCf! is suitable for this purpose. : Solvents that can be dissolved include nitrobenzene, chlorhenzene, dichlorobenzene, dichloromethane, trichloroethylene, chlornaphthalene, methylnaphthalene, benzene, toluene, kiln, tetrahydrofuran, chlorohexanone, 14-dioxane, N-methylpyrrolidone, carbon tetrachloride, Mention may be made of bromobutane, ethylene glycol, sulfolane, ethylene glycol monobutyl ether, acetoxyethoxyethane, pyridine, and the like. The solvent used in this invention is not limited to those mentioned above. These solvents may be used alone or as a mixture of two or more. Acetone, noclohexane, petroleum ether, methoxyethanol, acetonitrile, ethyl acetate, isopropyl alcohol, diethyl ether, methyl ethyl ketone,
Solvents such as ethanol, hexane, propylene carbonate, butylamine, water, etc. generally do not dissolve Ht-Pc. Therefore, in this invention, these solvents cannot be used alone; when these solvents are used, they must be used in combination with the above-mentioned solvent that dissolves H2-Pc. The binder polymer used in this invention is H, -P
c? It is preferable to use a material that dissolves in the above-mentioned solvent having a concentration of 8% f. Polymers suitable for this purpose include polyester, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polycarpo-F, polyvinyl butyral, polyvinyl acetoacetal, polystyrene, polyacrylonitrile, polymethyl methacrylate, and polyvinyl butyral. Acrylate, polyvinylcarbazole, and their copolymers, poly(vinyl chloride, vinyl acetate, vinyl alcohol), poly(vinyl chloride, vinyl acetate, maleic acid)
, poly(ethylene, vinyl acetate), poly(vinyl chloride/
(vinylidene chloride), cellulose polymers, various noroxane polymers, and the like. The binder polymer used in this invention is not limited to the above-mentioned polymers. These polymers may be used alone or as a mixture of two or more. When using a combination of two or more of the above solvents, it is possible to melt Hz-Pc with one solvent and melt the binder polymer with another solvent. The optimum ratio of HtPc to Hider polymer to metal Pc is between 5=1 and 1=2 by weight. H2~P
If the amounts of c and metal Pc are greater than this range, the battery properties themselves will be excellent, but the film performance will tend to deteriorate. On the other hand, when the ratio of H, -Pc and metal PcL:v is less than the above range, the battery characteristics tend to deteriorate. Metals that can be effectively used as barrier electrodes for solar cells according to the present invention include aluminum, indium, chromium, gallium, zinc oxide, tin, etc., while ohminoc electrodes include gold, silver, copper, cobalt, nickel, Examples include iron, tin oxide, nesa, indium oxide, and ITO. The conductive support serving as the substrate of the organic photoconductive layer is not particularly limited, and can be appropriately selected depending on the intended use. Preferred examples of O2 include metals such as aluminum, glass, paper, plastics, etc., on which a conductive layer is formed by metal vapor deposition or the like. Furthermore, it can take various shapes such as a belt shape and a sheet shape. Note that the solar cell according to the present invention is not limited to the above configuration, and for example, a surface protective layer may be formed as necessary. Next, examples of the present invention will be described in detail together with comparative examples. Example 1 - X-type Hz Pc (Fastogen Blue 8120B manufactured by Dainippon Ink), PbPc, and polyvinyl butyral (abbreviated as PVB, Esuresoku BM-2 manufactured by Tanemizu Chemical Industry Co., Ltd.) were dissolved in tetrahydrofuran. After thorough mixing and kneading, the obtained solution was applied onto a 7-layer electrode and treated in vacuum at 120''C for 1 hour to form a photovoltaic layer (thickness: 1.2 μm). ,
Thickness measurements were made with a Taly-step thickness gage. A thin translucent indium electrode was formed on the resulting photovoltaic layer by vapor deposition. The thickness is about 800 mm, and the light penetration rate is about 2%. The current-voltage characteristics under light irradiation and the current-voltage characteristics under photothermal irradiation of the solar cell thus obtained were measured using a polarographic analyzer (EG&G, model 174A). The light source is AMO (AM is an abbreviation for Air Mass, which means the amount of atmosphere through which sunlight passes, and this indicates the spectral distribution of sunlight. When it is incident perpendicular to the earth's surface, it is called AMI, and when it is outside the atmosphere, it is called AMO. Expressed in
), the intensity is 1 mW/cd. X type H, -Pc and Pb
Table 1 shows the characteristics when the ratio of Pc is fixed at 1:2 and the weight ratio of PVB to these is varied.Here, to calculate the conversion efficiency, the intensity of light incident on the front electrode surface is Instead, it uses the intensity of light incident on the surface of the organic material. (The following is a blank space) In Table 1, X-type HtPc is mixed only in particulate form, and it is thought that X-type H, -Pc dispersed in molecular form does not exist. The results are shown in Table 2. As shown in Table 2 and Table 1, the appropriate ratio of X-type H, -Pc and PbPc to PVB is between 5:1 and 1:2, and good characteristics can be obtained with a composition within this range. . Comparative Example 1 For comparison, the characteristics are shown when a mixed solvent of acetone and DMF is used for cutting with the same configuration as Example 1. Acetone and DMF dissolve PVB, but X-type H, -Pc
does not melt. Therefore, as shown in PVB Table 2, the characteristics of the solar cell of Comparative Example 1 produced by such a method are as follows:
The results are significantly worse than those of Example shown in Table 1. From this, for this invention, H,-
It can be seen that it is necessary that a part of Pc be dispersed in molecular form in the binder polymer. Example 2 - τ type HXPC (manufactured by Toyo Ink ■, Liopoton (Lio
photon T) tP)) and MgPc and P to TB used in Example] were dissolved in tetrahydrofuran at a II ratio of 1:3:2, and after thorough mixing and kneading, a solar cell was produced in the same manner as in Example 1. did. Its characteristics are ■. c: o,
70V, Isc: 4.50μA, 14, FF: 0
．． 65, η near, 5%, and showed the same excellent characteristics as when using X-type H, -Pc. Example 3 X-type H,-Pc and MgPc and various binder polymers were mixed in a ratio of 1:3:2, dissolved in tetrahydrofuran, thoroughly mixed and kneaded, and then mixed in the same manner as in Example 1. A solar cell was fabricated using this method. The results are shown in Table 3. Table 3 As shown in Table 3, when H,-Pc is composed of molecularly dispersed and particulate dispersed ones, excellent photosensitive characteristics can be obtained regardless of the type of polymer. can form a body. Example 4 X-type H1Pc, various metals Pc, and PVB were dissolved in tetrahydrofuran, thoroughly mixed and kneaded, and then a solar cell was produced in the same manner as in Example 1. The barrier electrode is aluminum. X type H! Table 4 shows the solar cell characteristics when the weight ratio of -Pc and gold W4Pc and PVB is 1:2:I. Here, the light source is 150W
Xe lamp and a 1/211 Jarrel Ash monochromator. The amount of light irradiated onto the sample (front electrode) using this light source is approximately 8011 W/cm. Note that, also here, the conversion efficiency is calculated using the intensity of light incident on the surface of the organic substance (0.6 mW/cd). (Left below) Table 4

[Brief explanation of the drawing]

The figure is a side sectional view showing the structure of a Schottky photoelectric conversion element. 1... Barrier electrode, 2... Photovoltaic layer, 3... Ohmic electrode, 4... Substrate.

Claims (1)

[Claims] 1. A binder polymer, a metal-free phthalocyanine molecularly dispersed in the binder polymer, an X-type metal-free phthalocyanine and/or a τ-type metal-free phthalocyanine dispersed in particles in the binder polymer, and a binder polymer. A solar cell with a photovoltaic layer consisting of metal phthalocyanine dispersed in particles in molecules. 2 The weight ratio of binder polymer and phthalocyanine is 2:
The solar cell according to claim 1, wherein the ratio is within the range of 1 to 1:5. 3. The metal phthalocyanine is at least one selected from copper phthalocyanine, lead phthalocyanine, tin phthalocyanine, zinc phthalocyanine, magnesium phthalocyanine, silicon phthalocyanine, vanadium phthalocyanine, chloroaluminum phthalocyanine, titanyl phthalocyanine, chloroindium phthalocyanine, and chlorogallium phthalocyanine. The solar cell according to claim 1 or 2.