Preparation method of array quantum dot solar cell
By modifying the interface of BiVO4 nanorod arrays with histidine, the problem of poor interfacial contact between oxide nanorods and PbS quantum dots was solved, achieving defect passivation, efficient quantum dot loading, and energy level optimization, thereby improving the photoelectric performance of array quantum dot solar cells.
Patent Information
- Application Number
- CN202610581726.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-29
- Publication Date
- 2026-07-24
AI Technical Summary
In existing technologies, the interfacial contact between oxide nanorods and PbS quantum dots is poor, resulting in defect states, energy level mismatch, and insufficient quantum dot adsorption, which leads to a decrease in the photoelectric performance of array quantum dot solar cells.
Histidine was used to modify the interface of BiVO4 nanorod arrays. Taking advantage of the bifunctional properties of histidine molecules, the defect states were passivated by the -COOH group and the imidazole ring was complexed with the PbS quantum dot surface to form a dense modification layer to improve the interface contact and energy level matching.
It significantly improves the loading capacity and light absorption capacity of PbS quantum dots, optimizes the interface charge transfer efficiency, reduces the carrier recombination probability, and improves the short-circuit current and photoelectric conversion efficiency of array quantum dot solar cells.
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Figure CN122458679A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar cell material technology, specifically relating to a method for preparing an array quantum dot solar cell. Background Technology
[0002] Quantum dot solar cells have become a research hotspot in third-generation photovoltaic technology due to their advantages such as tunable bandgap, multiexciton effect and solution processability. Among them, the composite structure composed of lead sulfide (PbS) quantum dots and oxide nanorod arrays (such as ZnO and TiO2) has attracted much attention because it has both high electron mobility and direct charge transport channels. However, this system faces a bottleneck of poor interfacial contact in practical applications, which seriously restricts the further improvement of the photoelectric performance of array quantum dot solar cells. The specific technical problems are mainly reflected in the following three aspects: First, the oxide nanorod surface generally has inherent defect states such as oxygen vacancies and dangling bonds. These defect states act as recombination centers for photogenerated carriers, capturing photogenerated electrons generated by PbS quantum dots, intensifying interfacial charge recombination, and causing a significant decrease in the cell's open-circuit voltage and fill factor. Second, there is an energy level mismatch between the oxide conduction band bottom and the PbS quantum dot conduction band, forming an electron transport barrier that hinders the efficient transfer of photogenerated electrons from PbS quantum dots to the oxide electron transport layer, reducing charge separation efficiency. More importantly, during the solution deposition of PbS quantum dots, the interaction between the oxide surface and the organic ligands (such as oleic acid) on the quantum dot surface is weak, resulting in a limited and uneven adsorption of quantum dots on the nanorod array, making it difficult to form a dense light-absorbing layer, thereby limiting the light absorption efficiency and increasing the leakage current.
[0003] To address the aforementioned interface issues, various interface modification strategies have been proposed in existing technologies, but all have significant limitations and cannot fundamentally achieve comprehensive optimization of interface performance. Inorganic passivation layers (such as Al2O3 and MgO) can passivate oxide surface defects and suppress charge recombination to a certain extent, but these passivation layers easily introduce additional series resistance and are difficult to finely control energy levels. Traditional short-chain organic molecules (such as mercaptopropionic acid) can bond with oxides through anchoring groups, shorten the distance between quantum dots and oxides to enhance electron tunneling, and utilize molecular dipole moments to adjust the work function, but their functions are relatively singular, usually only achieving surface passivation or ligand exchange, making it difficult to simultaneously meet the dual requirements of enhancing interfacial charge transfer and increasing quantum dot deposition. In addition, these short-chain organic molecules are prone to steric hindrance effects on nanorod arrays with complex morphologies, leading to uneven coverage of the modification layer, which in turn reduces the deposition amount of quantum dots on the array surface and fails to achieve the expected interface optimization effect.
[0004] Therefore, there is an urgent need to develop a novel oxide / organic interface composite modification system that can synergistically achieve oxide surface defect passivation, interface energy level optimization, and high-density quantum dot adsorption, thereby systematically improving the interface characteristics and photoelectric conversion efficiency of array quantum dot solar cells. Summary of the Invention
[0005] Based on the problems existing in the prior art, the present invention provides a method for preparing an array quantum dot solar cell, which aims to achieve defect passivation, energy level matching and efficient quantum dot loading through histidine interface modification, suppress interface recombination, and thereby improve the photoelectric performance of the array quantum dot solar cell.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for fabricating an array quantum dot solar cell includes the following steps: (1) A BiVO4 dense layer and a BiVO4 nanorod array were sequentially prepared on a conductive glass substrate as an electron transport layer; (2) A histidine monomolecule modified layer is deposited on the electron transport layer, and then PbS quantum dots are deposited on the histidine monomolecule modified layer as a light-absorbing layer. (3) Deposit a hole transport layer on the light-absorbing layer; (4) A metal electrode layer is deposited on the hole transport layer to obtain an array quantum dot solar cell.
[0007] Preferably, in step (1), the preparation step of the BiVO4 dense layer includes: dissolving 0.005 mol of Bi(NO3)3·5H2O, 0.005 mol of NH4VO3 and 0.01 mol of citric acid in 15 mL of nitric acid, heating and stirring until completely dissolved; taking 1 mL of the obtained solution, adding 0.08 g of polyvinyl alcohol and 0.25 mL of glacial acetic acid, stirring evenly and then spin-coating it onto the surface of a conductive glass substrate, and sintering at 400-550℃ for 3-7 h to obtain the BiVO4 dense layer.
[0008] Preferably, in step (1), the preparation steps of the BiVO4 nanorod array include: dissolving 0.002 mol of Bi(NO3)3·5H2O and 0.002 mol of NH4VO3 in 50 mL of nitric acid, adding 14.3 g of NaHCO3 to generate a yellow BiVO4 suspension; placing a conductive glass substrate coated with a dense BiVO4 layer face up in the BiVO4 suspension, growing at 40-80℃ for 4-8 h, and calcining at 400-550℃ for 3-7 h after growth to obtain the BiVO4 nanorod array.
[0009] Preferably, in step (2), the histidine is deposited by spin coating, and the concentration of the histidine solution used for spin coating is 0.05~10 mg / mL, and the solvent is isopropanol. The chemical formula of histidine is as follows:
[0010] Preferably, in step (2), the PbS quantum dots are prepared by a hot injection method, the steps of which include: adding 0.45 g PbO and 1.5 mL oleic acid to 18 mL octadecene, evacuating and stirring at 100°C for 0.5-2 h to obtain a lead source solution; adding 215 μL hexamethyldisiloxane to 10 mL octadecene, evacuating and stirring at 100°C for 0.5-2 h to obtain a sulfur source solution; and rapidly injecting the sulfur source solution into the lead source solution under an argon protective atmosphere and at 80°C, purifying the solution after it turns completely black to obtain PbS quantum dots.
[0011] Preferably, in step (2), the PbS quantum dots are deposited by spin coating, and the concentration of the PbS quantum dot solution used for spin coating is 50~300 mg / mL, and the solvent is butylamine.
[0012] Preferably, in step (3), the material of the hole transport layer is Spiro-MeOTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene).
[0013] Preferably, in step (4), the metal electrode is a gold electrode or a silver electrode.
[0014] The core advantage of the proposed method for fabricating array quantum dot solar cells lies in the interface modification of BiVO4 nanorod arrays using histidine. By leveraging the bifunctional properties of histidine molecules, this method simultaneously addresses key challenges in existing technologies, such as poor interfacial contact between BiVO4 and PbS quantum dots, insufficient quantum dot loading, severe interfacial charge recombination, and energy level mismatch. This significantly improves the photoelectric performance of the solar cells, with specific beneficial effects as follows: 1. Effective passivation of interfacial defects and suppression of charge recombination. The carbonyl oxygen atom in the -COOH group of the histidine molecule has a lone pair of electrons, which can form a stable chemical bond with the uncoordinated bismuth and vanadium vacancies on the surface of the BiVO4 nanorod array. This constructs a dense histidine monomolecular modification layer on the surface of the BiVO4 array, effectively covering and passivating the defect states on the BiVO4 surface, reducing photogenerated carrier recombination centers, and thus lowering the probability of interfacial charge recombination.
[0015] 2. Significantly increases PbS quantum dot loading and enhances light absorption. The imidazole ring at the other end of the histidine molecule can undergo specific complexation with lead atoms on the surface of PbS quantum dots, greatly enhancing the interaction between PbS quantum dots and the BiVO4 array surface. This not only significantly increases the loading of PbS quantum dots on the BiVO4 array surface but also improves the uniformity of quantum dot distribution, promoting the formation of a dense and continuous light-absorbing layer. This effectively broadens the light absorption range, improves light absorption efficiency, and thus increases the short-circuit current of the battery.
[0016] 3. Optimize the interface energy level arrangement to promote efficient charge transfer. The histidine monolayer forms a directional arrangement between the BiVO4 array and the PbS quantum dots. The inherent molecular dipole moment of histidine can precisely regulate the energy level matching relationship between BiVO4 and PbS quantum dots, reduce the potential barrier for photogenerated electrons to be injected from PbS quantum dots into the BiVO4 electron transport layer, increase the driving force for electron transfer, significantly improve the interface charge separation and transport efficiency, and further optimize the battery short-circuit current and photoelectric conversion efficiency.
[0017] In summary, this invention achieves a synergistic effect of "defect passivation, efficient quantum dot loading, and energy level optimization" through bifunctional interface modification of histidine. Compared with existing technologies without interface modification or traditional single-function modification, it can significantly improve the short-circuit current density and photoelectric conversion efficiency of array quantum dot solar cells. Moreover, the preparation process is simple, the cost is controllable, and no complex equipment is required, which has good prospects for industrial application. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of the array quantum dot solar cell of the present invention; Figure 2 The image shown is a scanning electron microscope (SEM) image of the BiVO4 array prepared in the embodiment of the present invention. Figure 3 Transmission electron microscope (TEM) images of PbS quantum dots prepared in the embodiments of the present invention; Figure 4 The solar cells of the various embodiments and comparative examples of the present invention J - V curve; Figure 5 The UV-Vis absorption spectra of the array quantum dot films prepared in Example 3 and the comparative example of this invention are shown below. Figure 6 The time-resolved fluorescence spectra of the array quantum dot films prepared in Example 3 and the comparative example of the present invention are shown below. Figure 7 The electrochemical impedance spectroscopy curves are those of the solar cells prepared in Example 3 and the comparative example of the present invention. Detailed Implementation
[0019] The present invention will be further described in detail below with reference to specific embodiments. The implementation of the present invention is not limited thereto. The described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.
[0020] Example 1 This embodiment prepares an array quantum dot solar cell according to the following steps: (1) Preparation of BiVO4 electron transport layer: 0.005 mol Bi(NO3)3·5H2O, 0.005 mol NH4VO3 and 0.01 mol citric acid were dissolved in 15 mL of 25% nitric acid and heated and stirred until completely dissolved; 1 mL of the resulting solution was taken, 0.08 g polyvinyl alcohol and 0.25 mL glacial acetic acid were added, stirred evenly and then spin-coated onto the surface of FTO conductive glass substrate, and sintered at 400℃ for 5 h to obtain BiVO4 dense layer. 0.002 mol of Bi(NO3)3·5H2O and 0.002 mol of NH4VO3 were dissolved in 50 mL of 15% nitric acid, and 14.3 g of NaHCO3 was added to generate a yellow BiVO4 suspension. A conductive glass substrate coated with a dense BiVO4 layer was placed face up in a round-bottom flask containing this suspension and grown at 50 °C for 6 h. After growth, it was calcined at 400 °C for 5 h to obtain a BiVO4 nanorod array. The dense BiVO4 layer and the BiVO4 nanorod array together constitute an electron transport layer. (2) Deposition of histidine monomolecular modification layer: Prepare a histidine isopropanol solution with a concentration of 0.5 mg / mL, spin-coat the solution onto the surface of the above BiVO4 nanorod array to form a dense histidine monomolecular modification layer.
[0021] (3) Preparation of PbS quantum dots: 0.45 g PbO and 1.5 mL oleic acid were added to 18 mL octadecene, and after vacuuming, the mixture was heated and stirred at 100 °C for 0.5 h to obtain a lead source solution; 215 μL hexamethyldisiloxane was added to 10 mL octadecene, and after vacuuming, the mixture was heated and stirred at 100 °C for 0.5 h to obtain a sulfur source solution; under an argon protective atmosphere and at 80 °C, the sulfur source solution was rapidly injected into the lead source solution, and the mixture was continuously stirred until the solution turned completely black to complete the reaction. The reaction solution was then purified: the reaction solution was transferred to a centrifuge tube and centrifuged at 20,000 rpm for 3 min, and the supernatant was discarded; 2 mL toluene was added and shaken to reconstitute the solution, and then 10 mL acetone was added to precipitate the solution, and the mixture was centrifuged again at 20,000 rpm for 3 min; after collecting the precipitate, it was vacuum dried at 35 °C for 24 h to obtain pure PbS quantum dots.
[0022] (4) Preparation of light-absorbing layer: Prepare a PbS quantum dot butylamine solution with a concentration of 300 mg / mL, spin-coat the solution onto the surface of the histidine monomolecule modified layer to form a light-absorbing layer.
[0023] (5) Preparation of hole transport layer and metal electrode: Spiro-OMeTAD solution with a concentration of 80 mg / mL was spin-coated onto the surface of the light-absorbing layer to form a hole transport layer; then a 60 nm thick Au electrode was deposited on the surface of the hole transport layer to obtain an array quantum dot solar cell.
[0024] Example 2 The preparation steps and process parameters of the array quantum dot solar cell in this embodiment are basically the same as those in Example 1. The only difference is that the concentration of histidine isopropanol solution in step (2) is 1 mg / mL.
[0025] Example 3 The preparation steps and process parameters of the array quantum dot solar cell in this embodiment are basically the same as those in Example 1. The only difference is that the concentration of histidine isopropanol solution in step (2) is 1.5 mg / mL.
[0026] Comparative Example The comparative example of the preparation of array quantum dot solar cells is basically the same as that of Example 1 in terms of preparation steps and process parameters. The only difference is that the histidine monomolecule modification layer deposition in step (2) is not performed, that is, the PbS quantum dot butylamine solution is directly spin-coated onto the surface of the BiVO4 nanorod array.
[0027] Photovoltaic performance tests were conducted on the array quantum dot solar cells obtained in each embodiment and comparative example under AM1.5 standard sunlight irradiation conditions, with an effective active layer area of 0.04 cm². 2 The JV curves for each embodiment and comparative example are shown below. Figure 4 As shown. The comparative battery short-circuit current is 12.93 mA / cm. 2 The open-circuit voltage was 0.488 V, the fill factor was 0.424, and the photoelectric conversion efficiency was 2.68%. The short-circuit current of the battery in Example 1 was 13.94 mA / cm². 2 The open-circuit voltage was 0.524 V, the fill factor was 0.444, and the photoelectric conversion efficiency was 3.24%; the short-circuit current of the battery in Example 2 was 14.89 mA / cm. 2 The open-circuit voltage was 0.544 V, the fill factor was 0.465, and the photoelectric conversion efficiency was 3.77%; the short-circuit current of the battery in Example 3 was 15.32 mA / cm. 2The open-circuit voltage was 0.555 V, the fill factor was 0.509, and the photoelectric conversion efficiency was 4.32%. This indicates that the short-circuit current and photoelectric conversion efficiency of the array quantum dot solar cell were significantly improved after histidine interface modification.
[0028] The array quantum dot films obtained in Example 3 and the comparative example were subjected to UV-Vis absorption spectroscopy tests, and the results are as follows: Figure 5 As shown, the absorbance of the film increased significantly after histidine interface modification, indicating an increase in the PbS quantum dot loading. Time-resolved fluorescence spectroscopy was performed on the arrayed quantum dot films obtained in Example 3 and the comparative example, and the results are as follows. Figure 6 As shown, after histidine interface modification, the interface charge transfer time decreased from 7.1 ns to 3.3 ns, indicating a significant improvement in charge transfer. Electrochemical impedance spectroscopy (EIS) tests were performed on the array quantum dot solar cells obtained in Example 3 and the comparative example, and the results are as follows: Figure 7 As shown, the interface charge transfer resistance increased significantly after histidine interface modification, indicating that interface charge recombination was suppressed.
[0029] The above test results fully demonstrate that the interface modification of BiVO4 nanorod arrays using histidine in this invention can effectively improve the uniformity of PbS quantum dot loading, enhance interfacial charge transport and suppress carrier recombination, significantly improve the photoelectric conversion performance of array quantum dot solar cells, and has good application prospects.
Claims
1. A method for fabricating an array quantum dot solar cell, characterized in that, Includes the following steps: (1) A BiVO4 dense layer and a BiVO4 nanorod array were sequentially prepared on a conductive glass substrate as an electron transport layer; (2) A histidine monomolecule modified layer is deposited on the electron transport layer, and then PbS quantum dots are deposited on the histidine monomolecule modified layer as a light-absorbing layer. (3) Deposit a hole transport layer on the light-absorbing layer; (4) A metal electrode layer is deposited on the hole transport layer to obtain an array quantum dot solar cell.
2. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (1), the preparation steps of the BiVO4 dense layer include: dissolving 0.005 mol of Bi(NO3)3·5H2O, 0.005 mol of NH4VO3 and 0.01 mol of citric acid in 15 mL of nitric acid, heating and stirring until completely dissolved; taking 1 mL of the obtained solution, adding 0.08 g of polyvinyl alcohol and 0.25 mL of glacial acetic acid, stirring evenly and then spin-coating it onto the surface of a conductive glass substrate, and sintering at 400-550℃ for 3-7 h to obtain the BiVO4 dense layer.
3. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (1), the preparation steps of the BiVO4 nanorod array include: dissolving 0.002 mol of Bi(NO3)3·5H2O and 0.002 mol of NH4VO3 in 50 mL of nitric acid, adding 14.3 g of NaHCO3 to generate a yellow BiVO4 suspension; placing a conductive glass substrate coated with a dense BiVO4 layer face up in the BiVO4 suspension, growing at 40-80℃ for 4-8 h, and calcining at 400-550℃ for 3-7 h after growth to obtain the BiVO4 nanorod array.
4. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (2), the histidine is deposited by spin coating, and the concentration of the histidine solution used for spin coating is 0.05~10 mg / mL.
5. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (2), the PbS quantum dots are prepared by hot injection method, which includes: adding 0.45 g PbO and 1.5 mL oleic acid to 18 mL octadecene, evacuating and stirring at 100 °C for 0.5-2 h to obtain lead source solution; adding 215 μL hexamethyldisiloxane to 10 mL octadecene, evacuating and stirring at 100 °C for 0.5-2 h to obtain sulfur source solution; and rapidly injecting the sulfur source solution into the lead source solution under argon protective atmosphere and at 80 °C. After the solution turns completely black, it is purified to obtain PbS quantum dots.
6. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (2), the PbS quantum dots are deposited by spin coating, and the concentration of the PbS quantum dot solution used for spin coating is 50~300 mg / mL.
7. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (3), the material of the hole transport layer is Spiro-MeOTAD.
8. The method for fabricating an array quantum dot solar cell as described in claim 1, characterized in that, In step (4), the metal electrode is a gold electrode or a silver electrode.
9. An array quantum dot solar cell, characterized in that: It is prepared by any one of claims 1 to 8.