Effect of Passivation on Buried Interface of CsPbI2Br Perovskite Films

Passivation on the surface or interface is one of the key issues in fabricating the efficient and stable perovskite solar cells (PSCs). In this Letter, we report a way to passivate the buried interface on the perovskite film by optimizing the growth kinetics of the precursor film. A solvent-controlled growth (SCG) strategy of the precursor film is adopted, that is, inducing the solvent volatilization of the precursor film before high-temperature annealing. It is found that the solvent distribution of the precursor film is the key to the growth kinetics of perovskite films. The vacuum pretreated precursor film can obtain a dense buried interface to avoid the generation of small grains and pores at the interfaces of the perovskite/electron transport layer after high temperature crystallization. After passivation, non-radiative recombination in CsPbI2Br films is suppressed, accompanied by favorable carrier separation and extraction at the interface. The power conversion efficiency of all-inorganic CsPbI2Br carbon-based PSCs without a hole transport layer reaches 13.46%. The SCG strategy on the precursor films provides a way to passivate the buried interface of PSCs.