JP2013089690A - Method for manufacturing quantum dot sensitized type solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a quantum dot sensitized solar battery which allows the formation of quantum dots made of a I-III-VI compound.SOLUTION: The method for manufacturing a quantum dot-sensitized solar battery with a photoelectrode which includes an oxide semiconductor layer 21 formed on a substrate 11 with a transparent electrode layer 20 and quantum dots 22 made of a I-III-VI group semiconductor formed on the oxide semiconductor layer 21 comprises the steps of: forming the oxide semiconductor layer 21 on the substrate 11 with the transparent electrode layer 20 formed thereon; forming, on the oxide semiconductor layer 21, fine particles having a I-VI group compound as a primary component by bringing the substrate 11 with the oxide semiconductor layer 21 formed thereon into contact with a metallic ion solution containing groups I and III elements, and a solution containing a group VI element alternately; and doping at least the group III element into the I-VI group compound.

Description

  The present invention relates to a method for producing a quantum dot-sensitized solar cell.

The solar cell, and solar cell silicon with crystalline silicon and amorphous silicon, GaAs-based, _CdTe-based, compounds based solar cell using a compound represented by _{CuIn (1-x) Ga x} Se 2 Already known. Recently, dye-sensitized solar cells using dyes as sensitizers and quantum dot-sensitized solar cells using inorganic semiconductor fine particles as photoelectric conversion materials have been studied. These dye-sensitized solar cells and quantum dot-sensitized solar cells are advantageous in that they have high theoretical conversion efficiency and can reduce manufacturing costs, and are promising as next-generation solar cells.

  Dye-sensitized solar cells have an electrode in which a dye is adsorbed as a sensitizer on an oxide semiconductor film formed on a transparent electrode layer. However, since an organic dye is used as a sensitizer, it is resistant to ultraviolet rays and high temperatures. There is a problem of low nature.

On the other hand, the quantum dot sensitized solar cell has a structure having an electrode in which inorganic semiconductor fine particles are formed as a sensitizer on an oxide semiconductor such as TiO ₂ and has high durability against ultraviolet rays and high temperatures. There are advantages. However, quantum dot-sensitized solar cells are currently in the research and development stage, and there is still room for improvement in quantum dot materials and the like. For example, although it has been disclosed that good performance is exhibited when CdS or PbS is adopted as the quantum dots (see Patent Document 1), it is not preferable to industrially use Cd or Pb having toxicity. Accordingly, the inventors have proposed that an I-III-VI group semiconductor such as CuInS ₂ , a so-called chalcopyrite compound semiconductor, may be used as the quantum dot material in place of the compound containing Cd or Pb.

JP 2008-16369 A

  On the other hand, as a method for adsorbing quantum dots such as CdS and PbS to an oxide semiconductor, a direct adsorption method, a chemical solution deposition method, an ion layer adsorption reaction method in which the quantum dots are alternately immersed in a metal ion solution, and the like are used.

  Of these, the direct adsorption method is a method in which a dispersant made of a quantum dot material is dispersed in a dispersion medium, and the dispersant is adsorbed on the oxide semiconductor. The compatibility between the hydrophobic portion of the dispersant and the oxide semiconductor is used. The adsorption rate of quantum dots is low due to the poor quality. The chemical solution deposition method is a method in which an oxide semiconductor is immersed in a solution that becomes a precursor of a quantum dot at a temperature below room temperature, and the quantum dots are adsorbed by a chemical reaction on the surface of the metal oxide. There is a problem that the uniformity of the dot particle size is not good and the deposition time is long. Among these, the ion layer adsorption reaction method has an advantage that the uniformity of the particle size of the quantum dots is relatively good and the production time is short.

  However, if the ion layer adsorption reaction method for generating binary quantum dots such as CdS and PbS is used by changing the material of the metal ion solution, for example, quantum dots having a composition close to that of the I-VI group compound As a result, it was difficult to produce quantum dots made of a group I-III-VI semiconductor.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a quantum dot-sensitized solar cell capable of forming quantum dots made of a group I-III-VI semiconductor. It is in.

  In order to solve the above problems, the invention according to claim 1 is an oxide semiconductor layer formed on a substrate having a conductive layer, and an I-III-VI group semiconductor formed on the oxide semiconductor layer. In a method for manufacturing a quantum dot-sensitized solar cell comprising a photoelectrode having a quantum dot comprising: a step of forming the oxide semiconductor layer on the substrate; and a substrate on which the oxide semiconductor layer is formed. Then, a metal ion solution containing a Group I element and a Group III element and a Group VI element-containing solution are alternately brought into contact with each other to form fine particles mainly containing an I-VI group compound on the oxide semiconductor film. The gist of the invention is to have a process and a process of doping at least a group III element into the group I-VI compound.

  According to invention of Claim 1, since the board | substrate with which the oxide semiconductor layer was formed is made to contact with the said metal ion solution and VI group element containing solution alternately, it is III group with high affinity with respect to an oxide semiconductor. After the element is adsorbed, the VI group element can be adsorbed, and further, the I group element having high affinity for the VI group element can be adsorbed. Further, since the group III element is doped into the fine particles of the group I-VI compound, quantum dots made of a group I-III-VI semiconductor having a sensitizing effect can be formed.

  Invention of Claim 2 is the manufacturing method of the quantum dot-sensitized solar cell of Claim 1, and the step of doping a Group III element is a Group III element-containing solution maintained at 160 ° C. or higher. The gist is to immerse the substrate on which the Group I-VI compound is formed.

  According to the second aspect of the present invention, since the group III element-containing solution is adjusted to the above temperature, the crystal of the group I-III-VI semiconductor can be obtained without completely dissolving the group I-VI compound in the solution. Can be promoted.

The invention of claim 3 is a method of manufacturing a quantum dot-sensitized solar cell according to claim 2, wherein the quantum dot is a CuInS _2, wherein the Group VI element-containing solution contains sulfur The group III element-containing solution contains group III element indium and sulfur, and the ratio of sulfur to indium is 2 or more and 5 or less.

  According to the invention described in claim 3, since the ratio (molar ratio) of sulfur contained in the group III element-containing solution is 2 or more and 5 or less with respect to indium, Sulfur can be doped. For this reason, the I-III-VI group semiconductor which has a sensitizing effect can be formed.

The schematic diagram which shows the cross section of the quantum dot sensitized solar cell produced by the manufacturing method of this invention. The schematic diagram which shows the principal part of the photoelectrode of the battery. The flowchart which shows the manufacturing process of this invention. The flowchart of an ionic layer adsorption reaction. It is a conceptual diagram of an ion layer adsorption reaction, (a) is immersed in a metal ion solution, (b) is immersed in a VI group element-containing solution, (c) and (d) are repeated alternate adsorption for several cycles. Indicates the state. The Raman scattering spectroscopy spectrum of an Example. The spectrum which expanded the wave number range of about 295 cm ^{-1 in} FIG. The graph which shows the elemental composition ratio of Cu, In, S of the quantum dot of a comparative example. The IPCE spectrum of the quantum dot which consists of CuS of a comparative example.

Hereinafter, an embodiment embodying a method for producing a quantum dot-sensitized solar cell of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the quantum dot-sensitized solar cell is opposed to the photoelectrode 12 through a photoelectrode 12 formed on a substrate 11 made of glass or the like, and a sealing material 14 provided in a frame shape. The counter electrode 13 is provided. The space formed between the photoelectrode 12 and the counter electrode 13 is filled with the electrolytic solution 15.

  As shown in FIG. 2, the photoelectrode 12 includes a transparent electrode layer 20 that is formed on the substrate 11 and serves as a light-transmitting conductive layer. For the transparent electrode layer 20, indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), or the like can be used. The film thickness of the transparent electrode layer 20 is usually in the range of 10 nm to 10 μm, preferably 100 nm to 1 μm. The resistivity of the transparent electrode layer 20 is preferably as low as possible, but it may be a resistivity of 5Ω / □ or more and 5000Ω / □ or less, and preferably 5Ω / □ or more and 50Ω / □ or less.

The photoelectrode 12 includes an oxide semiconductor layer 21 made of a metal oxide and formed on the transparent electrode layer 20, and quantum dots 22 adsorbed on the surface of the oxide semiconductor layer 21. The oxide semiconductor layer 21 is made of a metal oxide microcrystal. As the metal oxide, titanium oxide (TiO ₂ ), zinc oxide, tin oxide, niobium oxide, or the like can be used, and TiO ₂ is particularly preferable.

The particle diameter of TiO ₂ is preferably 10 nm or more and 1 μm or less, and more preferably 10 nm or more and 500 nm or less in order to increase the adsorption amount of the quantum dots 22. The thickness of the oxide semiconductor layer 21 may be 100 nm or more and 100 μm, and is preferably 5 μm or more and 20 μm or less.

The quantum dots 22 are made of a group I-III-VI semiconductor having a so-called chalcopyrite type crystal structure. The group I element is preferably Cu or Ag, the group III element is preferably In, Ga, or Al, and the group VI element is preferably S, Se, or Te. An I-III-VI group semiconductor is a combination of at least one of the above Group I elements, at least one of the above Group III elements, and at least one of the above Group VI elements. It is expressed by the composition formula. For example _{CuInS 2, CuInSe 2, CuInTe 2} , CuGaS 2, CuGaSe 2, CuGaTe 2, CuAlS 2, CuAlSe 2, CuAlTe 2, AgInS 2, AgInSe 2, AgInTe 2, AgGaS 2, AgGaSe 2, AgGaTe 2, AgAlS 2, AgAlSe ₂ , AgAlTe _{2 and the} like. _{Further, CuIn (1-x) Ga} x S 2, CuIn (1-x) Ga x Se 2, CuIn (1-x) Ga x Te 2, CuIn (1-x) Al x S 2, CuIn (1- _x) Al _x Se ₂ , CuIn _(1-x) Al _x Te ₂ , CuGa _(1-x) Al _x S ₂ , CuGa _(1-x) Al _x Se ₂ , CuGa _(1-x) Al _x Te ₂ Or a compound using a plurality of group III elements such as compounds in which Cu of these compounds is replaced with Ag (0 <x <1). Furthermore, Cu _(1-x) Ag _x InS ₂ , Cu _(1-x) Ag _x InSe ₂ , Cu _(1-x) Ag _x InTe ₂ , Cu _(1-x) Ag _x GaS ₂ , Cu _{(1- x)} Ag _x GaSe ₂ , Cu _(1-x) Ag _x GaTe ₂ , Cu _(1-x) Ag _x AlS ₂ , Cu _(1-x) Ag _x AlSe ₂ , Cu _(1-x) Ag _x AlTe ₂ Or a compound using a plurality of Group I elements (0 <x <1).

The counter electrode 13 is not particularly limited, but includes a transparent electrode layer formed on a substrate such as glass and a thin film made of platinum or carbon formed on the transparent electrode layer.
The electrolytic solution 15 is not particularly limited, but a solution containing sulfur is preferable.

  When light enters the quantum dot-sensitized solar cell, electrons excited in the quantum dot are injected into the oxide semiconductor layer 21 and move to the transparent electrode layer 20. The quantum dots 22 are regenerated by injecting electrons into the oxide semiconductor layer 21 and simultaneously oxidizing the ions in the electrolytic solution.

Next, a method for manufacturing the photoelectrode 12 will be described with reference to FIGS. First, as shown in FIG. 3, the oxide semiconductor layer 21 is formed on the substrate 11 on which the transparent electrode layer 20 is formed (step S1). The method for forming the transparent electrode layer 20 is not particularly limited. For example, a method of applying and baking a TiO ₂ paste by a squeegee method or the like can be employed. The firing temperature may be any temperature that can remove impurities and moisture. Specifically, it may be 100 ° C. or higher and 700 ° C. or lower, and preferably 400 ° C. or higher and 600 ° C. or lower. The heating time is about 30 minutes to 3 hours. As a result, a porous oxide semiconductor layer 21 is formed.

Next, a group I-VI compound is formed by a continuous ion layer adsorption reaction method in which the substrate 11 on which the oxide semiconductor layer 21 is formed is alternately immersed in a metal ion solution and a group VI element-containing solution (step S2). . Examples of the I-VI group compound include CuS, Cu ₂ S, Cu ₂ Se, CuSe, Cu ₂ Te, CuTe, Ag ₂ S, Ag ₂ Se, and Ag ₂ Te.

As shown in FIG. 4, in the continuous ion layer adsorption reaction method, first, it is immersed in a metal ion solution containing a group I element and a group VI element in which a group I compound and a group III compound are dissolved (step S2-1). . As the group I element compounds, chlorides, bromides, iodides, nitrates, sulfates, acetates, perchlorates, organic acid salts and the like such as Cu and Ag are preferably used. As the VI group compound, sodium sulfide _(Na 2 S), sodium selenide _(Na 2 Se), ether Logistics sodium _(Na 2 Te) is preferably used. The concentration of each solute is preferably 0.01M or more and 10M or less, particularly preferably about 0.1M.

  The immersion time may be a few minutes and the temperature may be about room temperature. Specifically, after the substrate 11 on which the oxide semiconductor layer 21 is formed is immersed in a metal ion solution for several minutes, it is cleaned with a cleaning solution such as ethanol (step S2-2) and dried at room temperature (step S2- 3).

  Thereafter, the substrate 11 is immersed in a Group VI element-containing solution for several minutes (Step S2-4), washed (Step S2-5), and dried (Step S2-6). The steps S2-1 to S2-6, i.e., immersion in the metal ion solution, washing and drying, immersion in the VI group element-containing solution, washing and drying may be performed only once. It is preferable to repeat the number of times 20 times or more. By repeating, the adsorption amount of the I-VI group compound to the oxide semiconductor particles can be increased. Moreover, even if it repeats exceeding 20 times, an adsorption amount does not change so much.

The mechanism assumed in this continuous ion layer adsorption reaction method will be described by taking as an example the case where an I-VI group compound made of CuS is formed in the oxide semiconductor layer 21 made of TiO ₂ . When the substrate 11 on which the oxide semiconductor layer 21 is formed is immersed in a metal ion solution containing monovalent Cu ions 101 and trivalent In ions (In ³⁺ ) 102, as shown in FIG. _It is considered that the In ions 102 are selectively adsorbed on the oxygen atoms 100 constituting ₂ . This phenomenon can be explained by the so-called HSAB rule (Hard and Soft Acids and Bases). The oxygen atoms 100 constituting TiO ₂ are classified into groups of “Hard” and “Bases”. The “hard base” tends to have a property of having a small ionic radius and being difficult to polarize, and has a higher affinity with the “hard” “acid”. For this reason, the In ions 102 classified into the “hard” and “acid” groups are selectively oxygenated rather than the monovalent Cu ions 101 classified as “soft” and “acids”. Adsorbed on the atom 100. As a result, in the first immersion in the metal ion solution, a large amount of In ions 102 are adsorbed on the oxygen atoms 100.

  Further, when the substrate 11 is immersed in the VI group element-containing solution, the sulfur ions 104 are adsorbed on the In ions 102 as shown in FIG. The sulfur ions 104 are classified as “soft bases”, but the ions classified into other bases do not exist in the group VI element-containing solution, and therefore the sulfur ions 104 are adsorbed.

  When the substrate 11 is immersed again in the metal ion solution in a state where the sulfur ions 104 are adsorbed on the In ions 102, as shown in FIG. 5C, the sulfur ions 104 are compared with the In ions 102 classified as “hard acid”. Cu ions 101 classified as “soft” and “acid” having high affinity are selectively adsorbed.

  When the substrate 11 is immersed again in the VI group element-containing solution, the sulfur ions 104 are adsorbed on the Cu ions 101. When immersion is repeated in this way, microcrystals made of CuS containing a small amount of In are formed as shown in FIG. This microcrystal becomes a precursor of the quantum dot 22.

  In addition, since the tendency of a polarizability is the same, the elements of each group are classified into almost the same group. Divalent Cu ions that are Group I elements are classified as “intermediate” and “acid” between “soft” and “hard”, and Ag ions are classified as “soft acid”. In ions, Ga ions, and Al ions that are Group III elements are classified as “hard acids”, and Se ions and Te ions that are Group VI elements have almost the same electronegativity as S ions. It is estimated that

  When the I-VI group compound is formed on the oxide semiconductor layer 21 by performing the continuous ion layer adsorption reaction method as described above, the precursor of the quantum dot 22 made of the I-VI group compound is formed as shown in FIG. On the other hand, doping with a group III element and a group VI element as dopants is performed (step S3). In the dope process, the temperature of a mixed solution in which a group III element compound and a group VI element compound are dissolved in a high boiling point organic solvent is adjusted to 160 ° C. or higher, and the substrate 11 is immersed in the mixed solution.

  As the group III element compound serving as a solute, chlorides, bromides, iodides, nitrates, sulfates, acetates, perchlorates, organic acid salts of In, Ga, and Al are preferably used. As the group VI element compound, the same compound as the group VI element-containing solution is used. Moreover, the reason why the group VI element as well as the group III element is used as the dopant is because the group VI element in the I-III-VI group semiconductor has a larger composition ratio than the group I element and the group III element, This is because the I-VI group compound, which is the precursor of the quantum dot 22, lacks the VI group element. The molar ratio of the group VI element to the group III element in the mixed solution is preferably 2 or more and 5 or less. When the ratio is less than 2, the group VI element is insufficient, and when the ratio exceeds 5, the group III element contained in the mixed solution is insufficient. When the molar ratio of the group VI element to the group III element in the mixed solution is within the above range, the quantum dot 22 has a chalcopyrite structure I-III- having a composition ratio of 1: 1: 2 to 1: 5: 8. It can be a group VI semiconductor.

  The organic solvent used in the mixed solution may be any solvent that can dissolve the above-described solute and has a boiling point equal to or higher than the minimum temperature of the dope. For example, oleylamine (boiling point: about 350 ° C.), trioctylamine (boiling point: 184 ° C.), 1-octadecene (boiling point 179 ° C.) can be used.

  As described above, the mixed solution is preferably maintained at 160 ° C. or higher. When the temperature is lower than 160 ° C., the I-VI group compound adsorbed on the oxide semiconductor layer 21 is dissolved in the solution, so that the I-III-VI group semiconductor cannot be generated. When the solution is 160 ° C. or higher, it is considered that crystallization of the I-III-VI group semiconductor is promoted.

As shown in FIG. 3, when the photoelectrode 12 is produced by doping, the photoelectrode 12 is dried (step S4). The photoelectrode 12 produced in this way is sealed in a state facing the counter electrode 13 through a sealing material 14 made of thermoplastic resin, and becomes a solar battery cell by injecting an electrolyte into the cell. .
Example 1
The glass substrate on which the transparent electrode layer made of fluorine-doped tin oxide (FTO) was formed was subjected to alcohol cleaning and UV ozone treatment, and then a TiO ₂ paste (manufactured by Solaronics, T-20 / SP, particle size 20 nm) was applied by a squeegee method with a thickness of 3 μm to 12 μm. Next, the substrate coated with the TiO ₂ paste was baked at 450 ° C. to form an oxide semiconductor layer.

Next, a metal ion solution was prepared so that the molar ratio of the CuCl solution (0.1 M) made of acetonitrile to the InCl ₃ solution (0.1 M) made of water was 1: 1. The substrate was immersed in a metal ion solution for 1 minute. Thereafter, the substrate was washed with ethanol and dried.

Furthermore, the substrate was immersed for 1 minute in Na 2 _S solution is VI group element-containing solution (0.1 M), washed with ethanol and dried.
When this cycle was repeated 5 times, it was confirmed by Raman scattering spectroscopy that fine particles made of CuS were formed on the oxide semiconductor particles (see FIG. 6). When the cycle was repeated twice and three times, a color change from brown to black was observed. Also, the 5 cycles substrate subjected, was observed with an electron microscope, adsorbed onto the TiO ₂ particles was confirmed microparticles of about 5 nm.

  Furthermore, a mixed solution was prepared by mixing a solution in which InI was dissolved in oleylamine and a solution in which sulfur powder was dissolved in octadecene so that the ratio of S to In was 4. Then, the mixed solution was kept at 250 ° C., and the substrate 11 on which fine particles made of CuS were formed was immersed.

Seven such samples were prepared, and the immersion time in the mixed solution was divided into 1 minute, 5 minutes, 10 minutes, 30 minutes, 60 minutes, and 180 minutes for each sample, and each sample was subjected to Raman scattering spectrometry (KAISER). The change of the adhesion amount of CuS and the change of the adhesion amount of CuInS ₂ were investigated by the company). For comparison, measurement was also performed on a sample in which only CuS was supported on the oxide semiconductor layer and was not doped (immersion time 0 minutes), and on a sample in which only the oxide semiconductor layer was supported.

As shown in FIG. 6, a peak corresponding to CuS was observed in the vicinity of 470 cm ^{−1 in} the sample having an immersion time of 0 to 60 minutes. In the sample with an immersion time of 1 minute, the intensity of the peak was not so different from that when the immersion time was 0 minute, but as the immersion time increased from 10 minutes to 180 minutes, the intensity of the peak decreased. , Almost disappeared in 180 minutes.

Further, as shown in FIG. 7, a peak corresponding to CuInS ₂ in the vicinity of 295 cm ⁻¹ was not observed in the sample having an immersion time of 0 minutes, but was observed in the sample having an immersion time of 1 minute to 180 minutes. The strength increased with time. From these results, it can be seen that even when the immersion time is several minutes, dopants S and In are doped into fine particles made of CuS to form CuInS ₂ having a chalcopyrite crystal structure.

  Next, a quantum dot-sensitized solar cell was produced using this photoelectrode. For a glass substrate on which a transparent conductive film made of fluorine-doped tin oxide (FTO) is formed, a platinum solution (Platisol, manufactured by Solaronics) is applied to the glass substrate by spin coating, and baked at 450 ° C. to form a counter electrode. Produced.

Furthermore, the counter electrode and the photoelectrode were opposed to each other through a frame-shaped high-milan (made by Mitsui DuPont Polychemical Co., Ltd.) made of a thermoplastic resin, and sealed by heating at 120 ° C. In addition, an electrolytic solution was injected into a space formed between the counter electrode and the photoelectrode. As the electrolytic solution, a solution obtained by dissolving Na ₂ S (0.6 mM), S (0.2 mM), and NaCl (0.2 mM) in a solvent obtained by mixing water and methanol was used.

Using solar simulators (WXS-50S-1, manufactured by Wacom Denso Co., Ltd.), 100 mW / cm ² of artificial sunlight is incident on the cells, and photoelectric conversion efficiency is obtained. Was measured. The photoelectric conversion rate at this time was 1.2%.
(Comparative Example 1)
In Comparative Example 1, only a continuous ion layer adsorption reaction method using a metal ion solution containing Group I and Group III elements and a Group VI element containing solution containing Group VI elements was performed. An attempt was made to make a semiconductor.

First, as in Example 1, an oxide semiconductor layer was formed on a substrate. Then, a metal ion solution adjusted so that the molar ratio of the CuCl ₂ solution (0.1M) and the InCl ₃ solution (0.1M) is 1: 1 is prepared, and the substrate is immersed in the metal ion solution for 1 minute. did. Thereafter, the substrate was washed with ethanol and dried.

Then, for 1 minute to Na ₂ S solution is VI group element-containing solution (0.1 M), washed with ethanol and dried. This cycle was repeated 5 times.
This sample was subjected to elemental analysis for each cycle using an electron beam microanalyzer (manufactured by Shimadzu Corporation). As a result, as shown in FIG. 8, in one cycle, the oxide semiconductor was represented by In ₂ S ₃ . The adsorbed compound was adsorbed, and the Cu composition ratio increased from 2 to 5 cycles. After 5 cycles of the alternating ionic layer adsorption reaction, Cu and S were approximately 1: 1, and the In ratio was extremely low.

  In the substrate where only CuS was adsorbed on the oxide semiconductor, as shown in FIG. 9, the intensity of the IPCE spectrum decreased as the adsorption was repeated. That is, it was suggested that when the adsorption amount of CuS increases, the quantum efficiency also decreases, and the battery performance decreases.

According to the above embodiment, the following effects can be obtained.
(1) In the said embodiment, when manufacturing the photoelectrode 12 of a quantum dot sensitized solar cell, the oxide semiconductor layer 21 was formed in the board | substrate 11 with which the transparent electrode layer 20 was formed. In addition, a continuous ion layer adsorption reaction method in which the substrate 11 was alternately immersed in a metal ion solution containing a group I element and a group III element and a group VI element containing solution was performed. The alternate immersion was repeated for several cycles. That is, after a group III element ion having a high affinity for the oxide semiconductor layer 21 is adsorbed, a group VI element ion having a high affinity for the group III element ion is adsorbed. Group element ions were adsorbed to form fine particles of precursors of quantum dots 22 made of a group I-VI compound. Furthermore, the substrate 11 on which the precursor of the quantum dots 22 was formed was immersed in a mixed solution containing a group III element and a group VI element maintained at 160 ° C. or higher. For this reason, the quantum dot 22 which consists of an I-III-VI group semiconductor which has a chalcopyrite crystal structure can be produced by doping the precursor of the quantum dot 22 with a group III element and a group VI element. Therefore, quantum dots 22 having a sensitizing effect can be generated without using toxic elements.

  (2) In the above embodiment, in the step of doping the group III element and the group VI element, the substrate 11 on which the group I-VI group compound is formed is immersed in the group III element-containing solution heated to 160 ° C. or higher. For this reason, crystallization of the I-VI group compound can be promoted without completely dissolving the Group I-VI compound in the solution.

(3) In the above embodiment, when the quantum dots 22 made of CuInS ₂ are formed, the ratio of S contained in the mixed solution is set to 2 or more and 5 or less with respect to In contained in the solution. Accordingly, the quantum dots 22 can have a chalcopyrite crystal structure having a sensitizing effect.

In addition, you may change this embodiment as follows.
In the above embodiment, when all the VI group elements constituting the I-III-VI group semiconductor can be adsorbed to the oxide semiconductor layer 21 only by the continuous ion layer adsorption reaction method, Group elements may not be used.

  In the above embodiment, the quantum dot sensitized solar cell is embodied as a type of battery that receives light from the photoelectrode 12 side. However, the counter electrode 13 is made of a translucent material and light is transmitted from the counter electrode side. May be embodied in a type of battery that is incident.

  DESCRIPTION OF SYMBOLS 11 ... Board | substrate, 12 ... Photoelectrode, 13 ... Counter electrode, 14 ... Sealing material, 15 ... Electrolyte solution, 21 ... Oxide semiconductor layer, 22 ... Quantum dot.

Claims (3)

Quantum dot-sensitized solar comprising a photoelectrode having an oxide semiconductor layer formed on a substrate having a conductive layer and a quantum dot made of a group I-III-VI semiconductor formed on the oxide semiconductor layer In the battery manufacturing method,
Forming the oxide semiconductor layer on the substrate;
The substrate on which the oxide semiconductor layer is formed is alternately brought into contact with a metal ion solution containing a group I element and a group III element and a group VI element-containing solution, so that I-VI is formed on the oxide semiconductor layer. Forming fine particles mainly composed of a group compound;
A method of manufacturing a quantum dot-sensitized solar cell, comprising: doping a group I-VI compound with at least a group III element. The process of doping group III elements
The method for producing a quantum dot-sensitized solar cell according to claim 1, wherein the substrate on which the group I-VI compound is formed is immersed in a group III element-containing solution maintained at 160 ° C or higher. The quantum dot is a CuInS _2,
The group VI element-containing solution contains sulfur,
3. The quantum dot-sensitized solar cell according to claim 2, wherein the Group III element-containing solution contains Group III element indium and sulfur, and the ratio of sulfur to indium is 2 or more and 5 or less. Production method.

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