JPS6140150B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pn heterojunction solar cell suitable for receiving solar energy and converting it into electrical energy by the photovoltaic effect. Conventionally, a structure in which a p-type layer is formed by diffusion on the surface of a thin plate of n-type silicon, for example, has been well known as a solar cell structure. It is also known that various semiconductors other than silicon, such as those based on p-n junctions, such as InP, GaP, Ga, As, and CdS, can be applied. However, on the surface of the substrate of these various n-type or p-type semiconductors,
It is extremely difficult to form a thin film layer that forms a p-n junction, and this has been conventionally used. For example, it is difficult to form such a semiconductor thin film using a CVD method, a vacuum evaporation method, or a sputtering method, and it is necessary to use special equipment. In other words, with conventional methods, it is extremely difficult to obtain a thin film layer that forms an efficient p-n junction with stable quality suitable for solar cells.
For this reason, there were problems in that productivity and economy were poor, and it was extremely expensive. The present invention aims to solve the above-mentioned problems and provide a pn heterojunction solar cell with high quality and good productivity. That is, in the present invention, acetylene is polymerized on the surface of n-type silicon to form a chain polyacetylene thin film having a conjugated double bond chain and a thickness of 10 μm or less on the surface of n-type silicon, and then trioxide is formed on the surface of n-type silicon. sulfur,
This is a p-n heterojunction solar cell obtained by treating a polyacetylene thin film with at least one compound selected from hydrochloric sulfuric acid, sulfuric acid, nitric acid, fuming nitric acid, super strong acids, and esters thereof. Some of the present inventors have already discovered and proposed a method for forming a polyacetylene thin film on a solid surface (Japanese Patent Publication No. 32581/1983). Following the above method, a thin film of polyacetylene is formed on the n-type silicon surface, the catalyst is washed away, and after drying,
By treating with the above-mentioned compound, a relatively high resistance p-type polyacetylene thin film can be made to have an electrical conductivity of 1Ω ^-1 cm.
By forming a p-type conductive polyacetylene thin film with a p-type conductivity of ^-1 or more, a pn heterojunction solar cell with high quality and good productivity can be manufactured. Hereinafter, the present invention will be explained in detail using the drawings. FIG. 1 shows one embodiment of the pn heterojunction solar cell of the present invention. That is, a p-type conductive polyacetylene thin film (2, polyacetylene thin film treated with sulfur trioxide, film thickness 0.8 μm) was applied to n-type silicon (doped with 3 phosphorus atoms) having an ohmic electrode 4 on one side. form p-n
A junction was made, and then a transparent electrode (1, coated with gold by chemical vapor deposition, film thickness: 0.50 μm) was formed on the p-type conductive polyacetylene thin film. The feature of the present invention is that a polyacetylene thin film having a thickness of 10 μm or less is formed on the n-type silicon surface by a polymerization method already known to those skilled in the art, and the formed polyacetylene thin film is then coated with sulfur trioxide, oleum, and sulfuric acid. , nitric acid, fuming nitric acid, super strong acids, and esters thereof. The band gap energy of polyacetylene is about 1.6 eV, and since it absorbs most of the energy of sunlight and becomes a photoconductor, the p-n heterojunction device obtained by the present invention
Its photovoltaic effect allows it to receive solar energy and convert it into electrical energy, making it an efficient p-
This becomes an n-heterojunction solar cell. According to the present invention, the thickness of the p-type conductive polyacetylene thin film can be easily controlled by the acetylene polymerization conditions, such as catalyst preparation conditions, catalyst concentration, catalyst amount, acetylene pressure, polymerization temperature, and polymerization time. Therefore, it is suitable for solar cells where control of the thickness of the polyacetylene film is an important factor. The present invention will be specifically explained below. The n-type silicon used in the present invention may be either single crystal silicon doped with a metal with the highest valence of 5, such as phosphorus or antimony, which is commonly used, or n-type amorphous silicon, which has been studied recently. However, in order to obtain high solar energy conversion efficiency, it is preferable to use n-type silicon single crystal. It is preferable to attach an ohmic electrode to one side of the n-type silicon used as shown in the drawing.
It is also possible to attach a lead wire directly to the silicon surface without attaching an ohmic electrode. The ohmic electrode can be manufactured by a CVD method, a vacuum evaporation method, a sputtering method, etc. which are commonly used in the industry. It is preferable to remove the oxide film on the surface of n-type silicon that contacts the polyacetylene film using a normal etching operation to leave a flexible silicon surface, but it is also possible to form a thin polyacetylene film on the oxide film without performing an etching operation. However, it is effective as a solar cell. For the etching operation, either a wet method or a dry method, which is widely practiced among those skilled in the art, can be used. The method for producing a polyacetylene film on the surface of n-type silicon can be carried out in accordance with the method already proposed by some of the present inventors (Japanese Patent Publication No. 32581/1983), but this method will be explained in detail. . As long as the polyacetylene to be produced is a linear polyacetylene having a double bond chain, there are no restrictions on the acetylene polymerization catalyst, but a catalyst system comprising a combination of a transition metal compound and an organometallic compound is usually used. The catalyst system may be either a homogeneous system or a heterogeneous system, but a homogeneous system is usually used because the catalyst can be easily removed. The transition metal compounds [catalyst component (A)] used to obtain the catalyst system used in the present invention include metals such as titanium, vanadine, chromium, iron, cobalt, tungsten, and molybdenum, and halogen atoms or at most 20 carbon atoms. Compounds containing alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkoxide groups, phenoxide groups, carboxylic acid residues, cyclopentadienyl groups, acetylacetone residues, carbon monoxide (carbonyl groups), and It is a complex between a compound and an electron-donating compound such as pyridine, triphenylphosphine, and dipyridyl. Among transition metal compounds, titanium, vanadine,
Compounds of iron, cobalt and chromium are preferred;
Particularly preferred are titanium compounds. Representative examples of preferred transition metal compounds include transition metal compounds whose general formulas are represented by formulas (1) to (3). Ti(OR ₄ ) (1) (R is an alkyl group having at most 20 carbon atoms) M(acac) ₃ (2) MO(acac) ₂ (3) [(acac) is an acetylacetonato group, M is a transition metal selected from titanium, vanadine, iron, cobalt, and chromium.] The organometallic compound [catalyst component (B)] used in the present invention is a transition metal selected from titanium, vanadine, iron, cobalt, and chromium. It is an organometallic compound containing at least one kind of metal, and the general formula of some of them is shown by the following formula. MRn [However, M is A, B, B, or a metal from Group B of the periodic table, and R has at most 20 carbon atoms.
alkyl, alkenyl, aryl
an organic group selected from the group consisting of aralkyl group, alkoxide group, phenoxy group, and cyclopentadienyl group, or a hydrogen atom or a halogen atom, which may be the same or different, but at least one of them is is a hydrogen atom or the organic group, and n is the highest valence number of the metal or a positive integer less than that.] Other organometallic compounds include pyridine, triphenylphosphine, Mention may be made of complexes with yne or diethyl ether and the reaction products of 1 mol of said organometallic compound with at most 2.0 mol of water, as well as double salts of two of said organometallic compounds. Among the organometallic compounds used in the present invention, typical ones include those containing magnesium, calcium, zinc, boron, aluminum, potassium, silicon, and tin. Organometallic compounds of aluminum and tin are preferred, and organoaluminium-based compounds are particularly preferred. Typical examples of the organoaluminum compounds include triethylaluminum, triisobutylaluminum, trihexylaluminum, diethylaluminum chloride, di-n-butylaluminum chloride, ethylaluminum sesquichloride, diethylaluminium butoxide, and the reaction of triethylaluminum with water. The product [reaction ratio 1; 0.5 (molar ratio)] is mentioned. Other organoaluminum compounds include aluminum siloxalene compounds, aluminum amide compounds, dialmoxalene compounds, and double salts containing the above organoaluminum compounds. The general formula of the aluminum-siloxalene compound used as the organometallic compound in the present invention is shown by the following formula. [However, R ¹ , R ² and R ³ may be the same or different and are a halogen atom or an alkyl group or alkoxy group having at most 10 carbon atoms, and R ⁴ is an alkyl group having at most 10 carbon atoms. and R ⁵
is a halogen atom, an alkyl group or alkoxy group having at most 10 carbon atoms, or a general formula of

【formula】 or

[Formula] (However, R ⁶ , R ⁷ and R ⁸ may be the same or different, and are the same as the above R ¹ , R ² and R ³ , and n
is a positive integer of 10 or less)] Representative examples of the aluminum-siloxalene compounds used in the present invention include trimethyldimethyl-siloxalene, trimethyldienyl-siloxalene, and trimethyldi-siloxalene. n
-Propyl-siloxsalene, trimethyl-diisobutyl-siloxsalene, trimethyldioctyl-
Mention may be made of siloxsalene, trichlorodimethyl-siloxsalene, dimethylethyldienyl-siloxsalene, trimethoxydimethyl-siloxsalene, triethyldimethyl-siloxsalene, trimethyldimethoxy-siloxsalene, trimethyldimethoxy-siloxsalene and trimethoxydichloro-siloxsalene. Further, the general formula of the aluminum amide compound used as the organometallic compound in the present invention is shown by the following formula. (However, R ¹ , R ² and R ³ may be the same or different and are a hydrogen atom or an alkyl group having at most 10 carbon atoms, and R ⁴ is a halogen atom or an alkyl group having at most 10 carbon atoms. ). Among the aluminum amide compounds used in the present invention, typical examples include diethylaluminum dimethylamide, diethylaluminum diethylamide, dimethylaluminum dimethylamide, dimethylaluminum di-n
-butyramide, diethylaluminium di-n-
butylamide, dichloroaluminum dimethylamide, dimethylaluminum dioctylamide,
Mention may be made of diisobutylaluminum di-n-butylamide and dihexylaluminum dioctylamide. The general formula of the dialmoxane compound used as the organometallic compound in the present invention is shown by the following formula. (However, R ¹ , R ² and R ³ may be the same or different and are a halogen atom or an alkyl group or alkoxy group having at most 10 carbon atoms, and R ⁴ is an alkyl group having at most 10 carbon atoms. Among the dialmoxane compounds used in the present invention, representative ones include tetramethyldialumoxane, tetraethyldialumoxane, tetraisobutyldialumoxane, and 1.1-
Dimethyl-3,3-diethyldialumoxane, tetraisobutyldialumoxane, 1,1-dimethyl-3,3-diisobutyldialumoxane, tetradecyldialumoxane, trimethyldialumoxane chloride and triethyldialumoxane chloride can give. Among the organometallic compounds used in the present invention, typical examples of organometallic compounds other than organoaluminum compounds include diethylmagnesium, ethylmagnesium chloride, methylmagnesium iodide, allylmagnesium chloride; normal propylmagnesium chloride, Tertiary-butylmagnesium chloride, phenylmagnesium bromide, diphenylmagnesium, ethyl ethoxymagnesium, dimethylzinc, diethylzinc, diethoxyzinc, dibutylboron chloride, diborein, trimethylboron, triethylsilane, silicon tetrahydride, triethylsilicone Hydride, tetramethyltin, tetraethyltin, trimethyltin chloride, dimethyltin dichloride, trimethyltin hydride, chains of ethylmagnesium bromide and ethyl ether, and reaction products of diethylzinc and water [H ₂ C/Zn ( C ₂ H ₅ ) ₂ <2.0 molar ratio)]. Further, as the organic compound used in the present invention, double salts of two types of the above-mentioned organic compounds (for example, lithium aluminum tetrahydride,
calcium (tetraethylzinc). In carrying out the present invention, only one kind of these organometallic compounds may be used, or two or more kinds may be used in combination. The molar ratio of the organometallic compound (B) to the transition metal of the catalyst component (A) used in the present invention is 1 to 100.
You can freely choose between, but it is not particularly limited to this. It is also possible to control the polymer yield, polymerization rate, etc. by combining these catalyst components (A) and (B) with a third component shown below, but these may or may not be used. The third component includes oxygen-containing compounds such as alcohols, ethers, peroxides, carboxylic acids,
Typical examples include acid anhydrides, acid chlorides, esters, ketones, etc., but nitrogen-containing compounds, sulfur-containing compounds, halogen-containing compounds, molecular iodine, and other Lewis acids can also be used. There is no particular restriction on the order of addition of these. The catalyst may be used as is without dilution, but
Usually, it is preferable to dilute with an aromatic or resinous inert organic catalyst, but when diluting, the concentration of the transition metal compound must be 0.001 mol/or more, and the transition metal compound must be diluted with an inert organic catalyst. The concentration is
If the amount is less than 0.001 mol/mol, it is difficult to obtain a good polyacetylene thin film. Since these catalysts decompose or change in quality as they react with oxygen or moisture in the air, they should be handled in a state substantially free of oxygen and moisture, such as in an inert gas such as nitrogen or argon gas, or in a vacuum. must be handled with. The above catalyst solution is applied to a well-dried n-type silicon surface that is substantially free of water and brought into contact with acetylene gas to form a polyacetylene thin film. The steric structure of polyacetylene can be controlled by changing the temperature during polymerization; at temperatures below 10°C, polyacetylene with many cis forms can be produced, while at temperatures above 10°C, polyacetylene with many trans forms can be produced. The polymerization temperature is preferably 300°C or lower; if it is higher than 300°C, decomposition of the polyacetylene occurs, which is undesirable. Polymerization of acetylene occurs by contacting acetylene gas with a catalyst. The acetylene pressure is not particularly limited, but from a practical standpoint, it is desirable to conduct the reaction at 10 atmospheres or less. Since the high molecular weight polyacetylene produced is not soluble in organic solvents, it precipitates out upon initiation of polymerization. Once a polyacetylene film of a predetermined thickness is obtained,
The remaining acetylene gas is removed, followed by washing several times with an organic solvent in which the oxygen- and water-free catalyst is dissolved to remove the remaining catalyst. Subsequently, the remaining organic solvent is removed by drying to obtain a p-n heterozygote of a p-type polyacetylene film and n-type silicon. The thickness of the polyacetylene film is preferably 10 μm or less, particularly preferably 2 μm or less, in order to transmit as much sunlight as possible. If the film thickness is 10 μm or more, the solar energy conversion efficiency will be extremely reduced. The thickness of the polyacetylene film can be easily controlled by adjusting catalyst preparation conditions, acetylene pressure, polymerization time, polymerization temperature, etc. The thinner the produced polyacetylene film, the greater the solar energy conversion efficiency, and is therefore desirable, but it is difficult to create a polyacetylene thin film with a thickness of 0.05 μm or less. The electrical conductivity of the polyacetylene of the p-n heterojunction type device obtained in this way is 10 ^-8 to ^{10 -5} Ω.
Although it is low at ^-1 cm ^-1 , it can still be used as a solar cell due to the photovoltaic effect, but in order to obtain a higher conversion efficiency, the polyacetylene film must be mixed with sulfur trioxide, oleum, sulfuric acid, nitric acid, fuming nitric acid, etc. The conductivity of the polyacetylene film is increased to 1Ω ^-1 by treating it with at least one compound selected from super strong acids and their esters.
By increasing the conversion efficiency to cm ^-1 or higher, it has become possible to manufacture solar cells with high conversion efficiency. As electron-accepting compounds that can increase the electrical conductivity of polyacetylene to a high level of 1 Ω ^-1 cm ^- ₁ or higher, (1) iodine ( ₂ ), bromine (Br ₂ ), and iodized bromine (IBr) have already been used. Halogens (ii) such as arsenic pentafluoride (ASF ₅ ), antimony pentafluoride (SbF ₅ ), silicon tetrafluoride (SiF ₄ ), phosphorus pentafluoride (PCl ₅ ) and phosphorus pentafluoride (PF ₅ ), etc. Metal halide (iii) difluorosulfonyl peroxide (F ₂ S ₂ O ₄ ) is known. The inventor of the present invention has determined that the electrical conductivity of polyacetylene can be increased to 1Ω using compounds other than those mentioned above.
^-1・cm ^-1 or higher and provide a p-type polyacetylene film. As a result of various studies, we found that the following treatment agents were selected from sulfur trioxide, oleum, sulfuric acid, nitric acid, fuming nitric acid, super strong acids, and their esters. The inventors have discovered that the electrical conductivity of polyacetylene can be increased to 1 Ω ^-1 ·cm ^-1 or more by treating the polyacetylene film with at least one type of compound, and have thus arrived at the present invention. The processing agent that can be used in the present invention is industrially extremely useful because it is less toxic and cheaper than arsenic pentafluoride and iodine, which are conventional electron-accepting compounds that give high electrical conductivity. . The super strong acid referred to in the present invention is a compound whose general formula is represented by formula (1). R ¹ −SO ₃ H (1) (R ¹ is a hydrocarbon residue with 5 or less carbon atoms substituted with Cl, F, or halogen) Typical examples include fluorosulfuric acid, chlorosulfuric acid, trifluoromethanesulfuric acid etc. can be given. These compounds represented by formula (1) contain at least 0.5 mole or less of sulfur trioxide, arsenic pentafluoride, thallium pentafluoride, and antimony pentafluoride per mole of the compound represented by formula (1). It may be used in combination with one type of compound. Furthermore, the ester of a super strong acid as used in the present invention is a compound whose general formula is represented by formula (2). R ¹ −SO ³ −R ² (2) (R ¹ is the same as formula (1), R ² is an alkyl group having 5 or less carbon atoms) Typical specific examples include methyl fluorosulfate,
Examples include ethyl fluorosulfate, methyl chlorosulfate, methyl trifluoromethanesulfonate, and ethyl trifluoromethanesulfonate. By treating the polyacetylene thin film of the pn heterojunction type device with these compounds, a solar cell with high conversion efficiency can be obtained. Methods for treating polyacetylene membranes with these compounds include (i) bringing the vapor of these compounds into direct contact with the polyacetylene membrane; and (ii) immersing the polyacetylene membrane in an inert organic solvent or water and then treating the polyacetylene membrane with these compounds. Method of introducing the compound (iii) A method of directly immersing the polyacetylene membrane in these compounds can be considered, but any method may be used. After treating the pn heterojunction type device with the above-mentioned compound, it is desirable to remove the excess compound unreacted with the polyacetylene by a conventional method such as washing with an inert organic solvent or vacuum drying. The p-type conductive polyacetylene thin film of the thus obtained p-type conductive polyacetylene thin film-n-type silicon p-n type heterojunction element may be attached directly to the p-type conductive polyacetylene thin film to form a solar cell. It is preferable to attach an ohmic transparent electrode and a lead wire to the converter because the conversion efficiency can be increased. The ohmic transparent electrode can be manufactured by the CVD method, vacuum evaporation method, sputtering method, etc. that are commonly used in the industry. Since the p-n junction solar cell manufactured by the above method is relatively susceptible to oxidative deterioration due to oxygen, it is preferable to use it in a vacuum or an inert gas atmosphere. Suitable packaging materials for this purpose include glass and plastics such as polycarbonate, polymethacrylate, and polyester, which are commonly used for solar cells. Example 1 Into a 200 ml reactor completely equipped with nitrogen gas, 40 ml of toluene purified according to a conventional method, 10 mmol of tetrabutoxytitanium, and 40 mmol of triethylaluminum were charged in this order at room temperature to prepare a catalyst solution. Prepared. The non-electrode side of an n-type silicon wafer (doped with phosphorus atoms, resistivity 5 to 15 Ωcm) with an ohmic electrode attached by vapor-depositing gold on one side was heated with concentrated nitric acid:fluoric acid = 5:1. After etching for 1 minute with an etching solution of (weight ratio), washing with a large amount of distilled water, and vacuum drying at room temperature. Approximately 0.2 ml of the above catalyst solution was dropped onto the etched surface of the above dried n-type silicon wafer under a nitrogen gas atmosphere to uniformly apply the catalyst solution to the silicon surface. The system was then evacuated to expel nitrogen gas, cooled to -78°C, purified acetylene gas at a pressure of 4 cmHg was introduced, and polymerization was carried out for 30 seconds. Immediately after the weight was finished, unreacted acetylene gas was expelled and replaced with nitrogen gas. The catalyst was completely removed by washing with a large amount of purified toluene under a nitrogen gas atmosphere while cooling to −78° C., and the remaining toluene was removed by vacuum drying at room temperature. A transparent polyacetylene film with a thickness of 0.5 μm uniformly covered the silicon surface. The polyacetylene film produced has a cis form.
It was a p-type semiconductor with an electrical conductivity of 95% and an electrical conductivity of 8×10 ⁻⁸ Ω ⁻¹ ·cm ⁻¹ . Platinum lead wires were attached to the polyacetylene surface and the silicon electrode surface of the obtained polyacetylene/n-type silicon wafer laminate using a conductive adhesive (trade name "Electro dag502"), and vacuum dried for 30 minutes to remove the adhesive. of the organic solvent was removed. The p-n heterojunction device obtained in this way was placed in a reaction container, and after exhausting the air in the system with a vacuum pump, the p-n heterojunction device was added to
was cooled to -78°C, and steam at that temperature and vapor pressure was introduced into the reactor and treated for 40 minutes. Subsequently, unreacted sulfur trioxide was evacuated to obtain a pn heterojunction solar cell. The electrical conductivity of this polyacetylene film was 480Ω ^-1 ·cm ^-1 . The thickness of the polyacetylene film of the solar cell obtained is
The diameter was 0.5 μm and the area was 0.2 cm ² . When the above solar cell was irradiated with sunlight (57.3 MW/cm ³ ) and the photovoltaic force was measured, the open circuit voltage was 0.41 V, the short circuit current was 4.45 mA/cm ² , and the film factor was 0.26. The efficiency was 0.83%. Example 2 Before attaching lead wires to the polyacetylene/n-type silicon wafer laminate obtained in Example 1, a transparent gold film electrode was attached to the surface of the polyacetylene film by vacuum evaporation, and platinum was applied thereto. A pn heterojunction solar cell was produced in exactly the same manner as in Example 1 except that lead wires were attached. When the photovoltaic force was measured in exactly the same manner as in Example 1, the conversion efficiency was 1.59%. Comparative Example 1 P-
We created an n-heterojunction solar cell. When the photovoltaic force was measured in exactly the same manner as in Example 1, the conversion efficiency was 0.12%. This comparative example shows that it is preferable to increase the electrical conductivity of the polyacetylene film from the viewpoint of increasing the conversion efficiency of the solar cell. Example 3 Untreated polyacetylene-n obtained in Example 1
Put the silicon p-heterojunction element and 50 ml of toluene into a glass reactor, cool the reaction container with liquid nitrogen, exhaust the air in the system with a vacuum pump, and then cool the reaction container to -78℃. did. Approximately 5
ml of trifluoromethane sulfate and cooled to −78°C.
After reacting for 2 hours, the mixture was returned to room temperature and treated for 24 hours. After treatment, remove this p with 50 ml of toluene under nitrogen atmosphere.
The -n heterojunction device was washed three times and then vacuum dried to remove residual toluene and trifluoromethane sulfate. When the conversion efficiency of the pn heterojunction solar cell thus obtained was measured in exactly the same manner as in Example 1, the conversion efficiency was 0.80%. Examples 4 to 8 A p-n heterojunction solar cell was prepared in the same manner as in Example 3, except that the compounds shown in Table 1 were used instead of the trifluoromethane sulfuric acid used in Example 2. The conversion efficiency was measured in the same manner as in Example 1. The results are shown in Table 1.

[Table] (Ω ⁻¹・cm ⁻¹ )
Example 4 Fluorosulfuric acid 89 0.61
Trifluorome 〃 5 Methyl tansulfate 156 0.70
le

[Table] Fluorosulfate 〃 8 79 0.59
Chill Example 9 The untreated p-n heterojunction device obtained in Example 1 was immersed in nitric acid (special grade reagent with HNO ₃ content of 61%) for 5 seconds, immediately pulled out, and exposed to sunlight in the same manner as in Example 1. The conversion efficiency as a battery was measured. Conversion efficiency was 0.62%. Example 10 The conversion efficiency was 0.58 in exactly the same manner as in Example except that sulfuric acid (H ₂ SO ₄ content 97%, for precision analysis, manufactured by Wako Pure Chemical Industries KK) was used instead of nitric acid used in Example 9.
% p-n heterojunction solar cell was obtained. Example 11 After putting fuming nitric acid (specific gravity 1.52, special reagent grade, manufactured by Kanto Kagaku Co., Ltd.) into a glass reactor and removing the air in the system with a vacuum pump, the untreated P obtained in Example 1 was The conversion efficiency as a solar cell was measured in the same manner as in Example 1 by suspending the -n heterojunction element in the gas phase portion of the container and treating it with fuming nitric acid vapor at room temperature for 2 minutes. Conversion efficiency was 0.51%. Example 12 Fuming sulfuric acid 10 was used instead of oleum nitric acid used in Example 11.
% (manufactured by Kanto Kagaku Co., Ltd., reagent grade 1) was used in the same manner as in Example 11, with a conversion efficiency of 0.66%.
A heterojunction solar cell was obtained.

[Brief explanation of the drawing]

The drawing is a conceptual diagram of a p-n heterojunction solar cell of the present invention, where 1 is a transparent ohmic electrode, 2 is a p-n heterojunction solar cell, and 2 is a p-n heterojunction solar cell.
3 represents a conductive polyacetylene thin film, 3 represents an n-type silicon single crystal thin plate (wafer), and 4 represents an ohmic electrode.

Claims (1)

[Claims] 1 A chain polyacetylene thin film having a conjugated double bond chain with a film thickness of 10 μm or less is formed on the n-type silicon surface, and then sulfur trioxide, oleum, sulfuric acid,
A p-n heterojunction solar cell obtained by treating a polyacetylene thin film with at least one compound selected from nitric acid, fuming nitric acid, superstrong acids, and esters thereof.