Preparation And Research Of High Efficiency And Thermal Stable Carbon-based Perovskite Solar Cells

In the past ten years,halide perovskite materials have attracted wide attention from people in the photovoltaic field due to their wide wavelength range of light absorption,low exciton binding energy,excellent charge transport performance and simple preparation process.It has become a leader in new types of photovoltaic semiconductor materials.The photoelectric conversion efficiency of its integrated photovoltaic devices has also rapidly increased from the initial 3.8%to the current 23.7%.However,the thermal stability of traditional perovskite materials is poor,which has become a bottleneck for its commercialization.Recent studies have shown that CsPbI2Br and Cs0.15FA0.85PbI3(FA=NH2CH=NH2+)have good thermal stability,but the problems such as immature film formation process and low photoelectric conversion efficiency still need to solve.In order to prepare flat and dense,high-efficiency photoelectric conversion of CsPbI2Br and Cs0.15FA0.85PbI3 perovskite film,the perovskite film formation process is studied in detail.The specific research contents are as follows:(1)The preparation of high-quality CsPbI2Br perovskite film is explored,it is found that the excessive addition of CsI in the perovskite precursor solution can effectively improve the quality of the film.By comparing the absorbance,fluorescence intensity and photoelectric conversion efficiency of CsPbI2Br perovskite film and its integrated devices with different CsI excess values,the optimal excess value of CsI is finally determined,to be 0.8 M,and the optimized thin film formula is(CsI)0.8(CsPbI2Br).The microscopic mechanism of CsI-assisted CsPbI2Br film formation is investigated by XRD tracking test.Finally,the optimized inorganic perovskite film is integrated into the carbon-based perovskite solar cells and achieves an efficiency of 10.73%,which is also the current efficiency record value of carbon-based CsPbI2Br perovskite solar cells.The carbon-based devices are tested for thermal stability at 85?(commercialization requirements)for 240 h,and the device efficiency remains above 95%of the initial value,indicating a good thermal stability for the prepared carbon-based CsPbI2Br perovskite solar cells(2)The preparation process of Cs0.15FA0.85PbI3 perovskite film is investigated,and it is found that the addition of EDACl2 in the perovskite precursor solution can effectively reduce the defect density of the film,increase the grain size and reduce the number of grain boundaries.Using UV-vis absorbtion,fluorescence,together with photoelectric measurements,the incorporated amount of EDACl2 in the perovskite precursor solution is optimized in detail to prepare an optimized perovskite film(EDACl2)1.5wt%(Cs0.15FA0.85PbI3)characteristics of lower surface roughness and better crystallinity.By EDACl2 modification,the perovskite solar cell achieves an enhanced photoelectric conversion efficiency from the initial 15.6%to 18.8%.The thermal stability of the carbon-based devices are tested at 85? for 240 h,showing that the device efficiency remains above 90%of the initial value,demonstrating its good thermal stability.