A preparation method of a sulfur-selenium antimony solar cell with uniform absorption layer component gradient

Abstract

The application provides a preparation method of a sulfur-selenium antimony solar cell with a uniform absorption layer component gradient. The optimization scheme for improving the longitudinal component distribution uniformity of the Sb2(S,Se)3 thin film and the band matching of the Sb2(S,Se)3 device by using a low-cost triethanolamine complexing agent solves the problems of the non-ideal longitudinal component gradient of the absorption layer caused by the too fast reaction precipitation in the hydrothermal reaction system. 2+ Sb 3+ reaction precipitation.

Description

Technical Field

[0001] The present invention belongs to the field of antimony sulfoselenide solar cells, and particularly relates to a preparation method of an antimony sulfoselenide solar cell with a uniform absorption layer composition gradient. Background Art

[0002] Antimony sulfoselenide (Sb2(S x Se 1-x )3, 0 < x < 1) has been widely studied and developed in the fields of photovoltaic devices, photocatalytic water splitting, photodetectors, indoor photovoltaics, energy storage, etc. due to its high stability, simple composition, rich reserves, excellent optoelectronic properties, high theoretical power conversion efficiency, etc. Especially in the applications of flexible or tandem devices related to Sb2(S x Se 1-x )3 thin-film solar cells, it has shown excellent performance and great development prospects. Among them, the Sb2(S,Se)3 alloy has excellent properties such as a quasi-one-dimensional ribbon structure, a high absorption coefficient (> 10 5 cm -1 ) and an adjustable bandgap (1.1 eV - 1.7 eV). According to the Shockley-Queisser (S-Q) limit theory, by adjusting the Se / (S + Se) ratio of the Sb2(S,Se)3 thin film, a photoelectric conversion efficiency of more than 30% can be achieved. At present, the hydrothermal method is considered to be one of the most effective methods for preparing high-efficiency Sb2(S,Se)3 solar cells. The highest efficiency of Sb2(S,Se)3 solar cells prepared based on the hydrothermal method has reached 10.81%, but there is still a large gap compared with the theoretical efficiency. Based on the hydrothermal deposition method, in the preparation of high-quality Sb2(S,Se)3 thin films, researchers have used methods such as additives (such as EDTA and NH4F), post-treatment (such as alkali metal solutions), backside etching or modification to improve the quality of Sb2(S,Se)3 thin films. However, due to the problem of uneven longitudinal component distribution of the thin film caused by uncontrollable reaction kinetics, there is still a lack of effective solutions, which will seriously limit the lattice orientation and energy band structure of subsequent devices, and further limit the improvement of carrier transport performance. As is well known, efficient carrier transport is crucial for reducing non-ideal carrier recombination losses in thin-film solar cells. Therefore, studying the formation mechanism of Sb2(S,Se)3 thin films with good performance is of great significance for improving carrier transport in Sb2(S,Se)3 thin-film solar cells based on the hydrothermal method. However, due to the different reaction activities of Se 2+ and S 2+ with Sb 3+ (Se 2+ is more active than S 2+ ), the stability of Sb2S3 precipitation (K SP = 10 -90 ) is higher than that of Sb2Se3 (KSP = 10 -113 The stability of the precipitate is poor. Therefore, especially for the sodium selenite sulfate system, process parameters such as reaction temperature and holding time have a significant impact on the composition distribution of the precursor film, leading to bandgap fluctuations in the Sb2(S,Se)3 film. This will greatly limit carrier transport in Sb2(S,Se)3 thin-film solar cells. To obtain high-performance Sb2(S,Se)3 thin-film solar cells using the hydrothermal method, there is an urgent need for an effective method to control this non-ideal deposition process. Seeking more effective strategies to make the longitudinal composition of the Sb2(S,Se)3 film controllable and homogenized, thereby suppressing carrier recombination losses caused by non-ideal bandgap alignment, is currently a key direction for achieving high-efficiency Sb2(S,Se)3 thin-film solar cells. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing antimony sulfide selenide solar cells with a uniform absorber layer composition gradient.

[0004] To address the above problems, this invention solves the following two technical issues:

[0005] (1) An optimized scheme was proposed to improve the uniformity of longitudinal component distribution in Sb2(S,Se)3 thin films and the bandgap matching of Sb2(S,Se)3 devices by using a low-cost triethanolamine complexing agent, thus solving the problem of Se in the hydrothermal reaction system. 2+ Same as Sb 3+ The problem of an undesirable longitudinal component gradient in the absorbent layer caused by excessively rapid reaction precipitation.

[0006] (2) This study reveals the intrinsic mechanism by which triethanolamine regulates the hydrothermal reaction kinetics of Sb2(S,Se)3 and improves the conversion efficiency of the device. This lays an important theoretical and experimental foundation for the development of controllable Sb2(S,Se)3 hydrothermal reaction and provides valuable reference for the subsequent preparation of high-quality Sb2(S,Se)3 thin films.

[0007] The introduction of triethanolamine has the following advantages: 1. It enables time-domain control of the reaction process and optimizes the Se / (S+Se) elemental ratio distribution of the Sb2(S,Se)3 thin film; 2. It suppresses band fluctuations in the Sb2(S,Se)3 device, resulting in a uniform band gradient in the Sb2(S,Se)3 thin film, thereby reducing minority carrier recombination and improving the photocurrent of the Sb2(S,Se)3 solar cell; 3. It improves the vertical growth orientation of the Sb2(S,Se)3 thin film and promotes carrier transport in the device.

[0008] The specific technical solution of this invention is as follows:

[0009] ①FTO substrate cleaning: The FTO substrate was ultrasonically cleaned with ethanol, acetone and deionized water respectively to remove stains on the substrate surface. After ultrasonic cleaning, the substrate surface was dried with an air gun for later use.

[0010] ② Deposition of CdS film: Mix deionized water, CdSO4 and ammonia, then heat at 66 °C for 2 min. After the mixture is heated, add thiourea and stir to mix evenly. Finally, place it on an FTO substrate and heat to deposit for 22 min. Remove the substrate and blow dry for later use.

[0011] ③CdCl2 treatment: Dissolve CdCl2 in methanol, and then spin coat the CdCl2 solution onto the CdS film using a spin coater. After spin coating, place the substrate on a hot plate at 400 °C and anneal it in air for 11 min. After annealing, allow it to cool for later use.

[0012] ④ Preparation of sodium selenosulfate solution: 0.3158 g selenium powder and 2.0166 g anhydrous sodium sulfite were poured into a hydrothermal reactor and 80 mL of deionized water was added. The hydrothermal reactor was then placed in a constant temperature magnetic stirring heating jacket and subjected to a hydrothermal reaction at 130 °C for 8 hours. After the reaction was completed and cooled, the solution was filtered with a filter syringe for later use.

[0013] ⑤ Preparation of Sb2(S,Se)3 absorber layer: The CdCl2-treated sample was attached to a glass slide with high-temperature double-sided adhesive. Then, 0.2671 g of potassium antimony tartrate trihydrate, 1.5884 g of sodium thiosulfate pentahydrate and 120 mg of triethanolamine were dissolved in 10 mL, 10 mL and 20 mL of deionized water, respectively. The three solutions were then mixed and stirred until the solution turned yellow. Subsequently, 5 mL of sodium selenose sulfate solution was added and stirred for 1 min. The glass slide was then placed obliquely into a polytetrafluoroethylene (PTFE) liner and the mixed solution was poured in. The PTFE liner was then placed in a hydrothermal reactor and placed in an oven at 130 °C for 3 hours. After the reaction was completed, the film surface was rinsed with deionized water and dried after cooling. Finally, the sample was placed in a glove box under a nitrogen atmosphere and annealed on a hot table at 360 °C for 10 min to improve the crystallinity of the film.

[0014] ⑥ Preparation of Spiro-OMeTAD hole transport layer: Set the spin coater to single-step operation mode, speed 3500 rpm, time 30 s, acceleration 1000 rpm / s; use a pipette to draw 20 uL of the prepared Spiro-OMeTAD solution and drop it onto the sample. After spin coating, anneal on a hot plate at 105 ℃ for 10 min.

[0015] ⑦ Evaporating Au Electrodes: Gold electrodes are prepared using thermal evaporation. A mask is placed in an evaporation machine, and the Au evaporation process is run. Finally, the device surface is divided into sections with an effective area of ​​0.09 cm².2 A small square.

[0016] The advantages of this invention are:

[0017] The efficiency of antimony sulfide selenide (Sb₂(S,Se)₃) solar cells based on the hydrothermal method has exceeded 10.0%. However, the uncontrollable nature of the hydrothermal process, due to the reactivity difference between selenium and the selenium source, makes the preparation of high-quality Sb₂(S,Se)₃ thin films a bottleneck for high-efficiency Sb₂(S,Se)₃ solar cells. This invention innovatively uses triethanolamine as a chelating agent to regulate the reaction kinetics of Sb₂(S,Se)₃ thin films. Results show that the triethanolamine chelating agent can achieve time-domain control of the reaction process, optimize the longitudinal Se / (S+Se) elemental ratio distribution of the Sb₂(S,Se)₃ thin film, reduce the band shift of the Sb₂(S,Se)₃ device, and promote the formation of a uniform band back gradient in the Sb₂(S,Se)₃ thin film. This reduces minority carrier recombination at the back contact, increases the photocurrent of the Sb₂(S,Se)₃ solar cell, and reduces diode leakage current. Attached Figure Description

[0018] Figure 1 (a)Sb2(S,Se)3 solar cells under AM 1.5 illumination JV (b) EQE curve of Sb2(S,Se)3 solar cell;

[0019] Figure 2 SEM images of (a) Sb2(S,Se)3 films without TEA and (b) with TEA, and XRD images of Sb2(S,Se)3 films without TEA and with TEA. Detailed Implementation

[0020] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in detail. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

[0021] Example 1

[0022] ①FTO substrate cleaning: First, wash the FTO substrate with detergent. Then, put the substrate into a beaker and sonicate it in an ultrasonic machine for 30 minutes with ethanol, acetone and deionized water respectively to remove the stains on the substrate surface. After ultrasonication, blow the moisture off the substrate surface with an air gun for later use.

[0023] ② Deposition of CdS thin film: First, pour 220 mL of deionized water, 32 mL of 15 mM CdSO4 solution and 42 mL of 28 wt% ammonia solution into a beaker and mix them. Then, heat the beaker in a 66℃ water bath for 2 min. After that, pour in 16 mL of 1.5 mM thiourea aqueous solution and stir to mix evenly. Finally, put the FTO substrate in and heat it at 66℃ for 22 min to deposit the film. Then, take out the substrate and blow it dry for later use.

[0024] ③CdCl2 treatment: Dissolve 15 mg of CdCl2 in 1 mL of methanol, and then spin coat the CdCl2 solution onto the CdS film using a spin coater. After spin coating, place the substrate on a hot plate at 400 °C and anneal it in air for 11 minutes. After annealing, allow it to cool for later use.

[0025] ④ Preparation of sodium selenosulfate solution: Pour 0.3158 g of selenium powder and 2.0166 g of anhydrous sodium sulfite into a hydrothermal reactor and add 80 mL of deionized water. Then place the hydrothermal reactor into a constant temperature magnetic stirring heating jacket and carry out a hydrothermal reaction at 130 °C for 8 hours. After the reaction is completed and cooled, filter with a filter syringe for later use.

[0026] ⑤ Preparation of the Sb2(S,Se)3 absorber layer: The CdCl2-treated sample was attached to a glass slide using high-temperature double-sided adhesive tape. Then, 0.2671 g of potassium antimony tartrate trihydrate, 1.5884 g of sodium thiosulfate pentahydrate, and 120 mg of triethanolamine were dissolved in 10 mL, 10 mL, and 20 mL of deionized water, respectively. The three solutions were then mixed and stirred on a magnetic stirrer until the solution turned yellow. Subsequently, 5 mL of sodium selenose sulfate solution was added, and after stirring for 1 min, the glass slide was placed obliquely into a polytetrafluoroethylene (PTFE) liner, and the mixed solution was poured in. The PTFE liner was then placed in a hydrothermal reactor and reacted in an oven at 130 ℃ for 3 hours. After the reaction, the film surface was rinsed with deionized water and dried after cooling. Finally, the sample was annealed for 10 min at 360 ℃ in a glove box under a nitrogen atmosphere to improve the crystallinity of the film.

[0027] ⑥ Preparation of Spiro-OMeTAD hole transport layer: The spin coater was set to single-step operation mode, with a rotation speed of 3500 rpm, a time of 30 s, and an acceleration of 1000 rpm / s. 20 μL of the prepared 36.6 mg / mL Spiro-OMeTAD solution was pipetted onto the sample. After spin coating, the sample was annealed on a hot plate at 105 °C for 10 min.

[0028] ⑦ Evaporating Au Electrodes: Gold electrodes are prepared using thermal evaporation. A mask is placed in an evaporation machine, and the Au evaporation process is run. Finally, the device surface is divided into sections with an effective area of ​​0.09 cm². 2 A small square.

[0029] Comparative Example 1

[0030] ①FTO substrate cleaning: First, wash the FTO substrate with detergent. Then, put the substrate into a beaker and sonicate it in an ultrasonic machine for 30 minutes with ethanol, acetone and deionized water respectively to remove the stains on the substrate surface. After ultrasonication, blow the moisture off the substrate surface with an air gun for later use.

[0031] ② Deposition of CdS thin film: First, pour 220 mL of deionized water, 32 mL of 15 mM CdSO4 solution and 42 mL of 28 wt% ammonia solution into a beaker and mix. Then heat the beaker in a 66 ℃ water bath for 2 min. After that, pour in 16 mL of 1.5 mM thiourea aqueous solution and stir to mix evenly. Finally, put in an FTO substrate and heat at 66 ℃ for 22 min to deposit the film. Then take out the substrate and blow it dry for later use.

[0032] ③CdCl2 treatment: Dissolve 15 mg of CdCl2 in 1 mL of methanol, and then spin coat the CdCl2 solution onto the CdS film using a spin coater. After spin coating, place the substrate on a hot plate at 400 °C and anneal it in air for 11 minutes. After annealing, allow it to cool for later use.

[0033] ④ Preparation of sodium selenosulfate solution: Pour 0.3158 g of selenium powder and 2.0166 g of anhydrous sodium sulfite into a hydrothermal reactor and add 80 mL of deionized water. Then place the hydrothermal reactor into a constant temperature magnetic stirring heating jacket and carry out a hydrothermal reaction at 130 °C for 8 hours. After the reaction is completed and cooled, filter with a filter syringe for later use.

[0034] ⑤ Preparation of the Sb2(S,Se)3 absorber layer: The CdCl2-treated sample was attached to a glass slide using high-temperature double-sided adhesive tape. Then, 0.2671 g of potassium antimony tartrate trihydrate and 1.5884 g of sodium thiosulfate pentahydrate were dissolved in 10 mL and 20 mL of deionized water, respectively. The two solutions were mixed and stirred on a magnetic stirrer until the solution turned yellow. Then, 5 mL of sodium selenose sulfate solution was added, and after stirring for 1 min, the glass slide was placed obliquely into a polytetrafluoroethylene (PTFE) liner, and the mixed solution was poured in. The PTFE liner was then placed in a hydrothermal reactor and reacted in an oven at 130 ℃ for 3 hours. After the reaction, the film surface was rinsed with deionized water and dried after cooling. Finally, the sample was annealed in a glove box under a nitrogen atmosphere at 360 ℃ for 10 min to improve the crystallinity of the film.

[0035] ⑥ Preparation of Spiro-OMeTAD hole transport layer: The spin coater was set to single-step operation mode, with a rotation speed of 3500 rpm, a time of 30 s, and an acceleration of 1000 rpm / s. 20 μL of the prepared 36.6 mg / mL Spiro-OMeTAD solution was pipetted onto the sample. After spin coating, the sample was annealed on a hot plate at 105 °C for 10 min.

[0036] ⑦ Evaporating Au Electrodes: Gold electrodes are prepared using thermal evaporation. A mask is placed in an evaporation machine, and the Au evaporation process is run. Finally, the device surface is divided into sections with an effective area of ​​0.09 cm². 2 A small square.

[0037] The efficiency of antimony sulfide selenide (Sb₂(S,Se)₃) solar cells based on the hydrothermal method has exceeded 10.0%. However, the uncontrollable nature of the hydrothermal process, due to the reactivity difference between selenium and the selenium source, makes the preparation of high-quality Sb₂(S,Se)₃ thin films a bottleneck for high-efficiency Sb₂(S,Se)₃ solar cells. This invention innovatively uses triethanolamine as a chelating agent to regulate the reaction kinetics of the Sb₂(S,Se)₃ thin film. Results show that the triethanolamine chelating agent enables time-domain control of the reaction process, optimizes the longitudinal Se / (S+Se) elemental ratio distribution of the Sb₂(S,Se)₃ thin film, reduces the band shift of the Sb₂(S,Se)₃ device, promotes the formation of a uniform band back gradient in the Sb₂(S,Se)₃ thin film, thereby reducing minority carrier recombination at the back contact, increasing the photocurrent of the Sb₂(S,Se)₃ solar cell, and reducing the diode leakage current. Figure 1 As shown in (b), the external quantum efficiency of the Sb2(S,Se)3 film is significantly improved in the 300-1100 nm wavelength range after the introduction of TEA, proving that TEA effectively improves the orientation and film quality of the Sb2(S,Se)3 film, thereby enhancing its photoresponse. To verify the improvement in film quality and orientation, the Sb2(S,Se)3 film was characterized by SEM and XRD. Figure 2It can be seen that: 1) Due to the introduction of TEA, the Sb2(S,Se)3 absorber layer film is more uniform and flat, and the antimony oxide secondary phase on the film surface is suppressed; 2) The preferred orientation of (021) and (061) of the Sb2(S,Se)3 absorber layer film is enhanced. Finally, under the optimization of TEA, the short-circuit current density and fill factor of Sb2(S,Se)3 solar cell are significantly improved, and its photoelectric conversion efficiency increases from 8.75% to 9.94%. From the above JV, EQE, SEM and XRD analysis results, it can be seen that the introduction of TEA effectively regulates the reaction kinetics of the hydrothermal deposition process of Sb2(S,Se)3 film, making the longitudinal Se / (S+Se) element ratio distribution of the film more uniform, thereby improving the quality of Sb2(S,Se)3 film and enhancing the (hk1) orientation of Sb2(S,Se)3 film. These optimizations resulted in smaller bandgap in the Sb₂(S,Se)₃ devices and a more uniform back-side gradient in the Sb₂(S,Se)₃ thin film, thereby reducing minority carrier recombination at the back-side contact and ultimately improving the photoelectric conversion efficiency of Sb₂(S,Se)₃ solar cells. This is one of the highest values ​​to date for Sb₂(S,Se)₃ solar cells using the sodium thiosulfate system. This will promote the industrialization of low-cost antimony selenide compound thin-film solar cells and provide valuable insights for the composition homogenization and reaction kinetics control of antimony-based chalcogenide solar cells.

[0038] Table 1 Performance parameters of Sb2(S,Se)3 solar cells under Control and TEA conditions.

[0039]

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a solar cell of antimony sulfoselenide with a uniform gradient of layer composition, characterized in that, The method comprises the following steps: ①FTO substrate cleaning; ②CdS thin film deposition; ③CdCl2 treatment: CdCl2 is dissolved in methanol, and then the CdCl2 solution is spin-coated on the CdS thin film by using a spin coater. After the spin coating is completed, the substrate is placed on a hot stage at 400 ℃ and annealed in an air environment for 11 min. After the annealing is completed, the substrate is cooled and prepared for use; ④Preparation of sodium selenosulfate solution: selenium powder and anhydrous sodium sulfite are poured into an autoclave, and deionized water is added. Then, the autoclave is placed in a constant-temperature magnetic stirring heating jacket, and a hydrothermal reaction is carried out at 130 ℃ for 8 hours. After the reaction is completed and the autoclave is cooled, the solution is filtered by using a filter syringe and prepared for use; ⑤Preparation of Sb2(S, Se)3 absorption layer: the sample treated by CdCl2 is attached to a glass slide by using high-temperature double-sided tape. Then, 0.2671 g of antimony potassium tartrate trihydrate, 1.5884 g of sodium thiosulfate pentahydrate and 120 mg of triethanolamine are respectively dissolved in 10 mL, 10 mL and 20 mL of deionized water. Then, the three solutions are mixed and stirred until the solution turns yellow. Subsequently, 5 mL of sodium selenosulfate solution is added, and after stirring for 1 min, the glass slide is placed in a polytetrafluoroethylene liner at an angle and the mixed solution is poured into the liner. Then, the polytetrafluoroethylene liner is placed in an autoclave, which is then placed in an oven at 130 ℃ and reacted for 3 hours. After the reaction is completed, the surface of the thin film is washed with deionized water and dried. Finally, in a nitrogen atmosphere glove box, the sample is placed on a hot stage at 360 ℃ and annealed for 10 min to improve the crystallinity of the thin film; ⑥Preparation of Spiro-OMeTAD hole transport layer; ⑦Evaporation of Au electrode.

2. The production method according to claim 1, characterized by, The operation of the FTO substrate cleaning in step ① specifically comprises the following steps: the FTO substrate is ultrasonically cleaned with ethanol, acetone and deionized water respectively to remove stains on the surface of the substrate. After the ultrasonic cleaning is completed, the surface of the substrate is blown dry with an air gun and prepared for use.

3. The preparation method according to claim 1, characterized in that, The operation of the CdS thin film deposition in step ② specifically comprises the following steps: deionized water, CdSO4 and ammonia water are mixed, and then heated at 66 ℃ for 2 min. After the heating is completed, thiourea is added and stirred until the solution is uniformly mixed. Finally, the FTO substrate is placed and heated to deposit a CdS thin film. After the CdS thin film is taken out and dried, it is prepared for use.

4. The production method according to claim 3, characterized by, The heating and deposition temperature in step ② is 66 ℃.

5. The preparation method according to claim 3, characterized in that, The deposition time in step ② is 22 min.

6. The method of claim 1, wherein, In the preparation process of the sodium selenosulfate solution in step ④, the amount of selenium powder is 0.3158 g, the amount of anhydrous sodium sulfite is 2.0166 g, and the amount of deionized water is 80 mL.

7. The preparation method according to claim 1, characterized in that, The preparation of the Spiro-OMeTAD hole transport layer in step ⑥ specifically comprises the following steps: the spin coater is set to single-step mode, the rotation speed is 3500 rpm, the time is 30 s, and the acceleration is 1000 rpm / s. 20 uL of prepared Spiro-OMeTAD solution is drawn by using a pipette and dropped on the sample. After the spin coating is completed, the sample is annealed on a hot stage.

8. The preparation method according to claim 7, characterized in that, The annealing temperature in step ⑥ is 105 ℃.

9. The preparation method according to claim 7, characterized in that, The annealing time in step ⑥ is 10 min.

10. The method of claim 1, wherein, In step ⑦, the Au electrode is prepared by using a thermal evaporation method. A mask plate is placed in an evaporation machine, and an Au evaporation program is run.

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