Effects Of Carrier Transport Layer Interface Modification And Preparation Method Optimization On The Performance Of Perovskite Solar Cells

Perovskite solar cells are favored by more and more researchers due to their low cost,simple preparation process,and rapid development of high efficiency.It has become one of the most popular research fields in the solar cell industry.The current research methods to improve the performance of perovskite solar cells include optimization of perovskite light absorption layer,interface control,and modification of carrier transport layer.Among them,the optimization of perovskite light absorption layer includes new synthesis of materials,improvement of perovskite film quality,and passivation of perovskite layers.This thesis focuses on improving the power conversion efficiency of perovskite solar cells by doping the carrier transport layer.This paper will elaborate from the following three aspects:1.Hybrid organic-inorganic perovskites have attracted intensive interests as the absorber layer in high-performance perovskite solar cells（PSCs）.The interface between the electron transport layer and the perovskite layer in perovskite solar cells has a large effect on the device performance.Herein,we report a perovskite solar cell with a cell structure of ITO/ETL/（FAPbI₃）_0.97（MAPbBr₃）_0.03/Spiro-OMeTAD/MoO₃/Ag,where poly（vinylpyrrolidone）（PVP）-doped SnO2 film works as the electron transport layer.We observe that the perovskite film grown on the PVP-SnO2 shows more uniform crystalline grains than the control sample grown on the pure SnO₂,and the electron mobility of PVP-SnO₂ film is higher than that of the pure SnO₂ film.Consequently,the PVP-SnO2 can efficiently extract electrons from the perovskite layer.As a result,the PSCs using the PVP-doped SnO2 ETL showed an increased power conversion efficiency（PCE）.The optimized device using the PVP-SnO₂electron transport layer shows an improved PCE of 19.55%,while the PSC using the SnO₂ electron transport later shows a PCE of 17.50%.Furthermore,it is feasible to add PVP into the electron transport layer of SnO2 to improve the performance of the planar perovskite solar cell device.2.Low bandgap lead-tin（Pb-Sn）hybrid perovskite solar cells（PVSCs）have gained a great deal of attentions due to their wide optical absorption range and environmental friendliness.Poly（3,4-ethylenedioxythiophene）:poly（styrenesulfonate）（PEDOT:PSS）is widely used as a hole transport layer for PVSCs.However,the metallic property of PEDOT:PSS causes a barrier at the interface between it and the active layer,thereby hindering the transport of photogenerated carriers.In this paper,in order to eliminate the influence of the interfacial barrier,the PEDOT:PSS surface was treated by hydroquinone（HQ）,which lowers the hole transport barrier at the interface,and consequently reduces the interfacial resistance as well.The leakage current in the device with the HQ-treated PEDOT:PSS is significantly reduced,and the surface modification improves the interfacial contact.Compared with the Pb-Sn hybrid PVSCs with the PEDOT:PSS hole transport layer,the power conversion efficiency of PVSCs with the HQ-PEDOT:PSS hole transport layer is improved by6.9%.3.In the process of preparing the perovskite thin film,the two-step solution spin-coating method is widely used,but the prepared device has a serious hysteresis effect,and the repeatability of the cell is poor.The quality of perovskite film is particularly important for device performance.In order to further improve the quality of perovskite film,this chapter mainly introduces a new type of high-quality perovskite film preparation technology.Compared with the device prepared by the two-step solution spin coating method,the device has high repeatability,and the device performance is improved,and the hysteresis effect is negligible.