Method for improving performance of thin film solar cell with top lining structure through air annealing

Abstract

The invention discloses a method for improving the performance of a thin film solar cell with a top lining structure through air annealing, which comprises the following steps of: preparing a CdS buffer layer on the surface of FTO (Fluorine-doped Tin Oxide) through a CBD (Cubic Boron Diamond) method, depositing an Sb2 (S, Se) 3 thin film on a deposited FTO / CdS sample by using a CBD process, carrying out annealing treatment on the prepared sample in a glove box filled with N2 at the temperature of 350 DEG C, and carrying out annealing treatment on the Sb2 (S, Se) 3 thin film on the Sb2 (S, Se) 3 thin film. And then selecting the samples to carry out air annealing treatment, wherein the optimal air annealing temperature is 180 DEG C. And finally, coating a spiro-OMeTAD layer through a spin coating method, and preparing the gold front electrode by using a thermal evaporation technology. According to the method for improving the performance of the top lining structure thin film solar cell through air annealing, through air annealing treatment, the photoelectric conversion efficiency of the Sb2 (S, Se) 3 thin film solar cell is improved to 8.1% from 7.15%, and crystal orientation, interface passivation and carrier transmission efficiency are all remarkably optimized.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic device fabrication technology, specifically to a method for improving the performance of thin-film solar cells with a top-layer structure through air annealing. Background Technology

[0002] The escalating energy crisis has led to a broad consensus on the necessity of sustainable development, making the advancement and utilization of renewable energy a focus of academic research. Among various renewable energy sources, solar energy stands out as an inexhaustible resource. Solar cells, as a key technology for utilizing solar energy, effectively convert solar energy into electrical energy. Although traditional thin-film photovoltaic materials (such as GaAs, CdTe, Cu(In,Ga)Se2, and others) have achieved high photoelectric conversion efficiency (PCE), their large-scale application is limited by the presence of toxic elements (such as Cd and As) or their high cost (such as In and Ga). Therefore, Sb2(S,Se)3, which is abundant and non-toxic on Earth, has attracted increasing attention in recent years due to its optimal absorption coefficient, suitable band gap, and stability.

[0003] However, the PCE of Sb₂(S,Se)₃ thin-film solar cells based on top-substrate structures is still far below the theoretical value, and the quality of the absorber layer and the heterojunction interface characteristics are crucial influencing factors. Traditional annealing processes often use nitrogen protection, which can reduce oxidation, but cannot effectively improve defects and carrier recombination problems at the heterojunction interface, and it is difficult to control the crystal orientation of Sb₂(S,Se)₃, leading to (hk₀) oriented crystal growth, which is detrimental to carrier transport. Therefore, it is necessary to design a method to improve the performance of top-substrate structure thin-film solar cells through air annealing to solve the above problems. Summary of the Invention

[0004] The present invention aims to provide a method for improving the performance of thin-film solar cells with a top liner structure through air annealing, thereby solving at least one technical problem existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for improving the performance of a top-mass thin-film solar cell by air annealing, wherein the solar cell comprises, from bottom to top, an FTO substrate layer, a CdS buffer layer, an Sb2(S,Se)3 thin film, and a spiro-OMeTAD layer, and the method for improving the performance of the top-mass thin-film solar cell includes the following steps:

[0007] S1: A CdS buffer layer is prepared on the FTO substrate by CBD deposition;

[0008] S2: A Sb2(S,Se)3 thin film is deposited on the CdS buffer layer by CBD process;

[0009] S3: Pre-anneal the deposited sample in a nitrogen atmosphere;

[0010] S4: Perform air annealing on the pre-annealed sample;

[0011] S5: Spin-coat the spiro-OMeTAD layer onto the Sb2(S,Se)3 thin film after air annealing; S6: Prepare the gold pre-electrode on the spiro-OMeTAD layer by thermal evaporation.

[0012] Preferably, the preparation of the CdS buffer layer includes: cleaning the FTO substrate layer and immersing it in a CBD solution containing deionized water, an aqueous NH3OH solution, cadmium sulfate (0.015M), and thiourea (0.75M), reacting at 85°C for at least 8 minutes and 30 seconds, followed by drying and CdCl4. 2 / Spin-coating in methanol solution, followed by high-temperature annealing and crystallization.

[0013] Preferably, the preparation of the Sb2(S,Se)3 thin film includes: immersing an FTO / CdS sample in a CBD solution containing selenourea (3mM), C4H4KO7Sb·0.5H2O (20mM), Na2S2O3·5H2O (80mM), and deionized water; reacting in a water bath at 95°C for 4 hours, followed by drying in a vacuum oven at 110°C for 1 minute.

[0014] Preferably, in step S3, the annealing temperature for pre-annealing the deposited sample in a nitrogen environment is 350°C.

[0015] Preferably, the annealing temperature for air annealing the pre-annealed sample in step S4 is 180°C.

[0016] Compared with the prior art, the method for improving the performance of thin-film solar cells with top liner structure by air annealing provided by the present invention has the following beneficial effects:

[0017] 1. Compared to traditional nitrogen annealing, post-air annealing significantly improves device performance. Air annealing optimizes the bandgap of the Sb2(S,Se)3 absorber layer and effectively passivates defects at the heterojunction interface, thereby suppressing interfacial carrier recombination. This treatment method enables the top-mass Sb2(S,Se)3 solar cell to achieve a high photoelectric conversion efficiency of 8.1%, which is significantly better than the nitrogen-annealed control device with an efficiency of only 7.15%.

[0018] 2. Air annealing promotes a more favorable (hk1) crystal orientation, increases the depletion width of photovoltaic devices, and reduces heterojunction interface defects. Furthermore, air-annealed devices exhibit stronger photoresponse capabilities. The lower Urbach energy also indicates that air annealing improves the stoichiometry of Sb2(S,Se)3 and reduces defects, thereby enhancing the device's conductivity.

[0019] 3. Air annealing improves crystal growth, resulting in larger grain sizes, which is typically associated with reduced defect density and improved carrier transport efficiency. Simultaneously, air annealing enhances the interfacial bonding between layers in photovoltaic devices, reducing interlayer gaps and positively impacting device stability and performance.

[0020] 4. Air annealing reduces interface defect density and recombination, promotes carrier transport and improves efficiency, thereby enhancing the overall performance of photovoltaic devices. Attached Figure Description

[0021] Figure 1 A flowchart of a method for improving the performance of thin-film solar cells with a top-mass structure by air annealing;

[0022] Figure 2 The combined effect of air annealing on the performance of Sb2(S,Se)3 photovoltaic devices is shown in several sub-figures (ad);

[0023] Figure 3 The combined effect of air annealing on the performance of the Sb2(S,Se)3 absorber layer is shown in multiple sub-figures (af);

[0024] Figure 4 The combined effect of air annealing on the interface properties of the device is shown in multiple sub-figures (ae);

[0025] Figure 5 The dark current-voltage (JV) characteristics and electrical parameters of solar cells under different annealing conditions are shown in multiple sub-figures (af).

[0026] Figure 6 This is a schematic diagram of the preparation process, including multiple sub-diagrams (ae). Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Please see the appendix Figure 1-6 As shown, this embodiment provides a method for improving the performance of a top-layer thin-film solar cell by air annealing. The solar cell consists of, from bottom to top, an FTO substrate layer, a CdS buffer layer, an Sb2(S,Se)3 thin film, and a spiro-OMeTAD layer. The method for improving the performance of the top-layer thin-film solar cell includes the following steps:

[0030] S1: A CdS buffer layer is prepared on the FTO substrate by CBD deposition;

[0031] S2: A Sb2(S,Se)3 thin film is deposited on the CdS buffer layer by CBD process;

[0032] S3: Pre-anneal the deposited sample in a nitrogen atmosphere;

[0033] S4: Perform air annealing on the pre-annealed sample;

[0034] S5: Spin-coat the spiro-OMeTAD layer onto the Sb2(S,Se)3 thin film after air annealing; S6: Prepare the gold pre-electrode on the spiro-OMeTAD layer by thermal evaporation.

[0035] In step S3, the annealing temperature for pre-annealing the deposited sample in a nitrogen environment is 350°C.

[0036] In step S4, the annealing temperature for air annealing of the pre-annealed sample is 180°C.

[0037] The preparation of the CdS buffer layer includes: cleaning the FTO substrate layer and immersing it in a CBD solution containing deionized water, NH3OH aqueous solution, cadmium sulfate (0.015M), and thiourea (0.75M), reacting at 85°C for at least 8 minutes and 30 seconds, followed by drying and CdCl4. 2 / Spin-coating in methanol solution, followed by high-temperature annealing and crystallization.

[0038] The preparation of the Sb2(S,Se)3 thin film includes: immersing an FTO / CdS sample in a CBD solution containing selenourea (3mM), C4H4KO7Sb·0.5H2O (20mM), Na2S2O3·5H2O (80mM) and deionized water; reacting in a water bath at 95°C for 4 hours, followed by drying in a vacuum oven at 110°C for 1 minute.

[0039] In this embodiment, as Figure 6 As shown, (a) the preparation of CdS, (b) spin-coating of CdCl2 / methanol solution, (c) the preparation of Sb2(S,Se)3, (d) spin-coating of Spiro-oMeTAD, and (e) the fabrication of Sb2(S,Se)3 solar cells, compared with traditional nitrogen annealing, post-air annealing significantly improved device performance. Air annealing optimized the band gap of the Sb2(S,Se)3 absorber layer and effectively passivated defects at the heterojunction interface, thereby suppressing interfacial carrier recombination. This treatment enabled the top-mass Sb2(S,Se)3 solar cell to achieve a high photoelectric conversion efficiency of 8.1%, significantly better than the nitrogen-annealed control device with only 7.15% efficiency, and the open-circuit voltage (V) was significantly lower. OC ), short-circuit current density (J SC The fill factor (FF) and fill factor (FF) were also improved.

[0040] The air annealing process optimizes the crystal orientation of the Sb2(S,Se)3 thin film, promotes crystal orientation growth, and produces a larger grain size. This is generally associated with reduced defect density and improved carrier transport efficiency, increasing the depletion width of the photovoltaic device, reducing interface defects, and improving carrier transport efficiency. Air annealing also improves the interfacial bonding between layers in the photovoltaic device and reduces interlayer gaps, which has a positive effect on improving device stability and performance. Furthermore, air annealing reduces the Urbach energy of the Sb2(S,Se)3 thin film, improves the stoichiometry and defect density, thereby enhancing the conductivity of the device.

[0041] In performance testing, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to study the surface morphology and elemental composition. A multimeter (Keithley, 2400 series) was used under standard conditions (100 mW / cm²). 2 The current density-voltage (JV) of the solar cell was measured using AM 1.5G at a speed of 10 mW / cm². 2 Up to 100mW / cm 2 Evaluation of Vt of Sb2(S,Se)3 solar cells under various light intensities OC and J SCDark current density-voltage measurements of these devices were performed using curves relating light intensity to light. A Keithley 2400 source meter with a Zolix SCS101 system was used to characterize the external quantum efficiency (EQE) of the devices. Capacitance-voltage (CV) and drive-level capacitance (DLCP) of the solar cells were characterized using a Keithley 4200A-SCS and a Janis cryogenic platform. Furthermore, electrochemical impedance spectroscopy (EIS) analysis was performed on these photovoltaic devices using a CHI600E electrochemical workstation.

[0042] like Figure 2 As shown, the comprehensive impact of air annealing on the performance of Sb₂(S,Se)₃ photovoltaic devices is illustrated. Through multiple sub-figures (ad), (a) S N350 S A160 and S A180 The JV curve of the device, (b)S N350 S A160 and S A180 The instrument's EQE, (c) from S N350 S A160 and S A180 The bandgap of the device calculated by EQE, (d) from S N350 S A160 and S A180 The Urbach energy obtained from the EQE of the solar cell was compared with the current density-voltage (JV) curves, external quantum efficiency (EQE), band gap, and Urbach energy under different annealing conditions. The results show that air annealing significantly improves the photoelectric conversion efficiency (PCE) of the device, optimizes the light absorption performance, and improves the stoichiometry and defects of Sb2(S,Se)3.

[0043] like Figure 3 As shown, the combined effect of air annealing on the performance of the Sb2(S,Se)3 absorber layer is illustrated. Through multiple sub-figures (af), (a) S N350 and S A180 XRD pattern of the device, (b)S N350 The surface morphology of Sb2(S,Se)3 in the device, (c)S A180 The surface morphology of Sb2(S,Se)3 in the device, (d)S N350 and S A180 Statistical distribution of Sb2(S,Se)3 grain size in the device, (e)S N350 and (f)S A180 The cross-sectional morphology of the apparatus was compared, and XRD patterns, surface morphology, grain size statistics, and cross-sectional morphology under different annealing conditions were examined. The results indicate that air annealing promotes...

[0044] The carrier transport in the Sb2(S,Se)3 absorption layer optimizes crystal growth, increases grain size, and enhances the interfacial bonding between layers.

[0045] like Figure 4 As shown, the combined effect of air annealing on the interface properties of the device is illustrated. Through multiple sub-figures (ae), (a)S N350 and S A180 The CV and DLCP curves of the device, (b)S N350 and S A180 1 / C of the device 2 -V curve, (c)S N350 and S A180 Nyquist plot of the device, (d)V OC The power-law dependence of the value on light intensity, (e)J SC The power-law dependence of light intensity was compared with the CV and DLCP curves under different annealing conditions, and the 1 / C ratio was also analyzed. 2 -V curve, Nyquist plot and V OC and J SC The results show a power-law dependence on light intensity. These results indicate that air annealing significantly reduces the interface defect density, optimizes carrier distribution, improves carrier collection efficiency, and enhances the device's built-in electric field (V0). bi ) and open-circuit voltage (V OC ).

[0046] like Figure 5 As shown, the dark current-voltage (JV) characteristics and electrical parameters of solar cells under different annealing conditions are illustrated. Multiple subplots are presented: (a) dark JV, (b) shunt conductance G, (c) series resistance R and ideality factor A, and (d) S. N350 and S A180 The reverse saturation current density J0 of the device is shown in (e) and (f), which are Sb2(S,Se)3 solar cells annealed with N2 and air, respectively. The dark JV curves, shunt conductance G, series resistance R, ideality factor A, and reverse saturation current density J0 under different annealing conditions are compared. The results show that air annealing significantly reduces interfacial recombination and optimizes the rectification characteristics and carrier transport efficiency of the device.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for improving the performance of a top-mass structure thin-film solar cell by air annealing, characterized in that, The solar cell, from bottom to top, consists of an FTO substrate layer, a CdS buffer layer, an Sb2(S,Se)3 thin film, and a spiro-OMeTAD layer. The method for improving the performance of the top-mass structure thin-film solar cell includes the following steps: S1: A CdS buffer layer is prepared on the FTO substrate by CBD deposition; S2: A Sb2(S,Se)3 thin film is deposited on the CdS buffer layer by CBD process; S3: Pre-anneal the deposited sample in a nitrogen atmosphere; S4: Perform air annealing on the pre-annealed sample; S5: Spin-coat a spiro-OMeTAD layer onto the air-annealed Sb2(S,Se)3 thin film; S6: Pre-gold electrode is prepared on the spiro-OMeTAD layer by thermal evaporation.

2. The method for improving the performance of a top-mass structure thin-film solar cell by air annealing according to claim 1, characterized in that, The preparation of the CdS buffer layer includes: cleaning the FTO substrate layer and immersing it in a CBD solution containing deionized water, NH3OH aqueous solution, cadmium sulfate (0.015M), and thiourea (0.75M), reacting at 85°C for at least 8 minutes and 30 seconds, followed by drying and CdCl4. 2 / Spin-coating in methanol solution, followed by high-temperature annealing and crystallization.

3. The method for improving the performance of a top-mass structure thin-film solar cell by air annealing according to claim 1, characterized in that: The preparation of the Sb2(S,Se)3 thin film includes: immersing an FTO / CdS sample in a CBD solution containing selenourea (3mM), C4H4KO7Sb·0.5H2O (20mM), Na2S2O3·5H2O (80mM) and deionized water; reacting in a water bath at 95°C for 4 hours, followed by drying in a vacuum oven at 110°C for 1 minute.

4. The method for improving the performance of a thin-film solar cell with a top liner structure by air annealing according to claim 1, characterized in that: In step S3, the annealing temperature for pre-annealing the deposited sample in a nitrogen environment is 350°C.

5. The method for improving the performance of a top-mass structure thin-film solar cell by air annealing according to claim 1, characterized in that: In step S4, the annealing temperature for air annealing of the pre-annealed sample is 180°C.

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