Fabrication Of Hybrid Perovskite Solar Cells Via Vapor-assisted Solution Process

Owing to their excellent optoelectronic properties（suitable bandgap,long carrier lifetime,low trap density,etc.）,hybrid organic–inorganic perovskite has become a research hotspot in the fields of photoelectric detection,light-emitting diodes,solar cells and so on.Among them,perovskite solar cells have caused a lot of research with the rapid improvement of their photovoltaic performance.In the past decade,its certified power conversion efficiency has rapidly increased from 3.81%to 25.2%,which is considered to be one of the most promising photovoltaic technologies,and the high-quality perovskite layer is the key to its excellent photoelectric performance.The vapor-assisted solution process（VASP）has been proven to be one of the most effective ways to fabricate high-performance PSCs.However,the bottom of the perovskite layer prepared by this method often produces residual PbI_2,which affects the device performance.This thesis first optimizes the preparation process of the VASP method,then the2D-3D heterojunction perovskite solar devices are prepared by the vapor treatment device,and the role of molecular occupancy of n-butylamine in the morphology control of PbI₂ layer and the elimination of residual PbI₂ were also explored,including the following three parts:（1）Explore the influence of the preparation method of PbI₂ film on the performance of perovskite devices,and optimize the preparation process of PbI₂ film.At the same time,the ratio of spiro-OMe TAD and Li-TFSI in the hole transport layer is optimized,so that the basic process of VASP can be optimized,and the optimal PCE of the device can reach 14.67%.（2）By optimizing the gas phase processing device,BA saturated vapor was used to process the 3D perovskite film,and then a 2D perovskite thin layer was covered on the surface of the 3D perovskite to prepare a 2D-3D heterojunction perovskite device.The 2D perovskite thin layer has improved the contact interface between the perovskite layer and the hole transport layer,promoted carrier transport,and increased the device PCE to 16.01%.（3）Aiming at the problem that unreacted PbI₂ often remains in the perovskite film,the PbI₂layer is treated by BA vapor to form an intermediate under the role of molecular occupation.This treatment method effectively regulated the morphology of PbI₂ and the crystallization process of perovskite,and the complete conversion of PbI₂ to perovskite is accelerated,thereby eliminating residual PbI₂ and promoting the growth of perovskite grains.The optimal PCE of the device reached 17.63%.