Stitching Perovskite Grains with Perhydropoly(Silazane) Anti‐Template‐Agent for High‐Efficiency and Stable Solar Cells Fabricated in Ambient Air

Abstract

All inorganic CsPbI3perovskite solar cells (PSCs) have emerged as disruptive photovoltaic technology owing to their admirable photoelectric properties and the non‐volatile active layer. However, the phase instability against moisture severely limits the fabrication environment for the high‐efficiency devices, breaking through the confinement region to achieve scalable manufacturing has been the primary issue for future commercialization. Here, we develop a curing‐anti‐solvent strategy for fabricating high‐quality and stable black‐phase CsPbI3perovskite films in ambient air by introducing an inorganic polymer perhydropolysilazane (PHPS) into methyl acetate to form anti‐template agent. The cross‐linked PHPS reduces moisture erosions while the hydrolyzate silanol network (–Si(OH)4–) controls the perovskite crystal growth by forming Lewis adducts with PbI2during the fabrication. The polycondensation adduct of Si–O–Si/Si–O–Pb strongly binds to CsPbI3grains as a shield layer to hamper phase transition. Using the inorganic CsPbI3perovskite thin‐film with PHPS‐modified anti‐solvent processing as the light absorber, the n–i–p planar solar cell achieved an efficiency of 19.17% under standard illumination test conditions. More importantly, the devices showed excellent moisture stability, retaining about 90% of the initial efficiency after 1000 h under 30% RH.