Buried interface release tensile strain for all inorganic perovskite solar cells

Releasing residual stress and reducing interface defects are crucial approaches for improving the photoelectric conversion efficiency and performance stability of perovskite solar cells (PSCs). This research introduces nickel chloride (NiCl 2 ) into the electron transport layer of tin dioxide (SnO 2 ) and applies it to the buried interface of all-inorganic CsPbBr 3 PSCs to prepare carbon-based FTO/SnO 2 -NiCl 2 /CsPbBr 3 /C cell devices. Through the morphological and structure characterization, it is found that introducing nickel chloride facilitates the formation of large and dense perovskite films with residual strain released and the passivation of interface defects. Simultaneously, an analysis of the interfacial energy level structure reveals that optimized energy levels enhance electron-hole separation and transport efficiency while effectively suppressing non-radiative recombination. The open-circuit voltage of the all-inorganic perovskite solar cell base on the SnO 2 -NiCl 2 electron transport layer reaches to 1.591 V, and optimal photoelectric conversion efficiency (PCE) of the solar cell devices has been improved from 8.11 % of the control to 9.33 % with NiCl 2 , and the unencapsulated device V OC long term stability maintained 96.9 % within 30 days under atmospheric environment conditions. This study provides new insights into the design of efficient electron transport layer materials to enhance the photovoltaic and environmental stability of PSCs.