Crystallization Dynamic Control of Perovskite Films with Suppressed Phase Transition and Reduced Defects for Highly Efficient and Stable All-Inorganic Perovskite Solar Cells

The performance of all-inorganic CsPbBr 3 solar cells for photovoltaic applications is governed by the phase compositions of 3D CsPbBr 3 and its Cs–Pb–Br derivatives of 0D Cs 4 PbBr 6 or 2D CsPb 2 Br 5 . Herein, a general method was proposed by using CsBr/CH 3 OH treatment to suppress the phase transitions and reduce surface defects of CsPbBr 3 films revealed by theoretical calculation and experiments. The formation energies (Δ H ) for various phase transition processes verify that low concentration CsBr/CH 3 OH treatment can effectively inhibit the harmful 0D Cs 4 PbBr 6 formation, further repairing the surface defects of perovskite and improving the photovoltaic performance. The hole transport layer (HTL)-free CsPbBr 3 PSC achieves a champion efficiency of 9.48% with an impressive 1.54 V open-circuit voltage and excellent long-term stability. It is worth mentioning that adding a thin ZnO layer on TiO 2 /CsPbBr 3 interface can increase the efficiency of CsPbBr 3 –PSC to 10.67% with improved short-circuit current and open-circuit voltage. The advanced CsPbBr 3 -based PSCs can benefit from these insights into accurately controlling the Cs–Pb–Br perovskite phase transition and surface properties.