Remarkable quality improvement of CsPbIBr_2 perovskite film by cellulose acetate addition for efficient and stable carbon-based inorganic perovskite solar cells
【摘要】：All-inorganic CsPbIBr_2 perovskite has been regarded as a promising candidate for perovskite solar cells(PSCs) considering its suitable bandgap and high stability. However, the poor quality of CsPbIBr_2 film greatly impedes the performance improvement of CsPbIBr_2-based PSCs. Herein, we report a facile strategy to improve the quality of CsPbIBr_2 perovskite film by introducing cellulose acetate(CA) into the perovskite precursor solution. The interaction between the oxygen functional groups of CA and Pb~(2+) and the increase of the precursor viscosity induced by CA addition can slow down the crystallization rate of CsPbIBr_2 perovskite, which allows the perovskite films have enough time to form highquality crystal structure. By optimizing the amount of CA( the optimal amount of CA is 2.5 wt%), a high-quality CsPbIBr_2 perovskite film with high crystallinity, large grain size, and smooth surface is obtained. As consequence, the carbon-based PSC with a structure of FTO/TiO_2/perovskite/carbon using the CsPbIBr_2 perovskite film with 2.5 wt% CA achieves a champion efficiency of 7.52%, which is increased by 40.8% compared with the cell based on pure CsPbIBr_2 perovskite film. In addition, the PSC based on CsPbIBr_2 film with CA exhibits an excellent long-term stability under both ambient condition and high-humidity environment.