Performance Of Double Perovskite Cs₂AgBiBr₆ Film And Solar Cell

The low cost,straightforward preparation process,and remarkable photoelectric conversion efficiency of Perovskite Solar Cells（PSCs）have caused a great deal of interest.Their certified efficiency has now attained a remarkable 25.7%.The rapid advancement of perovskite solar cells has been remarkable,yet their steadiness and matters like lead contamination still impede their further progress.The emergence of the all-inorganic halide double perovskite material Cs₂AgBiBr₆provides a new idea for the large-scale development of perovskite solar cells.Replacing organic cations（MA+,FA+,etc.）with Cs+and substituting Ag+and Bi3+for Pb2+,perovskite material stability is improved and the issue of Pb2+pollution to the environment is resolved.However,due to the wide bandgap of Cs₂AgBiBr₆,poor light absorption performance,and limited solubility in organic solvents,the crystallinity of the perovskite film it generates decreases,which affects the performance of the solar cell device.This article uses interface modification,additive engineering,and introduces carbon quantum dots,FeBr3,and CuBr2 to respectively modify the TiO2 electron transport layer and dope the Cs₂AgBiBr₆ perovskite material to improve the crystallinity of the Cs₂AgBiBr₆ film,improve the film morphology,optimize the energy level alignment of the perovskite solar cell,enhance the light absorption performance of Cs₂AgBiBr₆,and prepare stable and high-performance carbon electrode double perovskite solar cells.This article’s primary contents are as follows:Optimization of substrate temperature to improve the performance of Cs₂AgBiBr₆ double perovskite solar cells:In this work,Cs₂AgBiBr₆ film deposition conditions were optimized,and the film quality was improved by preheating the FTO substrate and TiO2 electron transport layer.By controlling the substrate temperature,the effect of different preheating temperatures on the morphology of Cs₂AgBiBr₆ films was investigated.Experimental studies showed that with the increase of preheating temperature,the crystallinity and grain size of Cs₂AgBiBr₆ films also increased.The best film quality was obtained at a preheating temperature of 40℃,while at 50℃,although the grain size became larger,obvious holes appeared on the film surface.Finally,the optimal device with a PCE of 1.21%was obtained at a preheating temperature of 40℃.This work laid a foundation for the optimization of the performance of Cs₂AgBiBr₆ double perovskite solar cell devices in the future,explored the preparation conditions of Cs₂AgBiBr₆ standard devices,and subsequent work will be carried out based on this work.Carbon dot sensitization to enhance the performance of Cs₂AgBiBr₆ double perovskite solar cells:To enhance carrier transport efficiency and modify the energy level matching of perovskite solar cell devices,this work modifies the surface of TiO2 electron transport layer based on the concept of co-sensitization,and prepares double perovskite solar cells with FTO/TiO2&TiO2-CQDs/Cs₂AgBiBr₆/carbon electrode structure.Compared with the unmodified devices,the double perovskite solar cell devices based on TiO2-CQDs film show significantly improved performance.The device efficiency,sensitized for 10 hours,is augmented from the standard device’s 1.20%to 1.89%by optimizing the sensitization time further.The research results show that the introduction of carbon quantum dots optimizes the energy level matching between TiO2/Cs₂AgBiBr₆ interface,enhances the crystallinity and morphology of Cs₂AgBiBr₆ film,improves the light absorption performance of perovskite film,and effectively prolongs the stability of double perovskite solar cell devices.Doping Fe or Cu to Improve the Performance of Cs₂AgBiBr₆ Double Perovskite Solar Cells:In this work,an additive engineering strategy was adopted to introduce FeBr3 and CuBr2 with different doping ratios into the Cs₂AgBiBr₆ single crystal preparation process.Fe3+and Cu+/Cu2+were used to modify Cs₂AgBiBr₆ by replacing Bi3+and Ag+to enhance its crystallinity and improve its film morphology.The FTO/TiO2/Cs₂AgBiBr₆/carbon electrode structure solar cells were prepared,and the photovoltaic performance of both material and device were studied.By optimizing the doping ratios,the device efficiency was improved from 1.20%to 1.51%when the Fe3+doping concentration was 0.3%,and from 1.16%to 1.46%when the Cu doping concentration was 0.5%.The research data showed that Fe3+and Cu+/Cu2+doping enhanced the crystallinity of Cs₂AgBiBr₆,optimized the film morphology,improved the energy level alignment of perovskite solar cells,and enhanced the carrier mobility of Cs₂AgBiBr₆ films.In addition,the doped devices exhibited excellent long-term stability,and the hysteresis effect was also improved.