Regulated perovskite crystallinity via green mixed antisolvent for efficient perovskite solar cells

Abstract

Abstract Organometallic halide perovskite absorption layer with excellent surface morphology and large grain size is very important for fabricating efficient perovskite solar cells (PSCs). The antisolvent assisted crystallization (ASAC) has been proved to be an effective tactic to prepare compact and uniform polycrystalline perovskite film. However, most of the antisolvents currently used are highly toxic, and the perovskite crystallization process is difficult to control using pure antisolvent. Here, a green strategy is developed to improve the nucleation kinetics of perovskite precursor and the perovskite crystallization process. A mixed green antisolvent of ethyl acetate (EA)/petroleum ether (PE) is employed to regulate the crystallization of perovskite and replace traditional chlorobenzene (CB) and pure EA. With optimized proportion of EA and PE, the supersaturation degree is controlled via reducing the solvent evaporation rate and the nucleation rate, and it is good for crystal growth. Moreover, the grain growth rate and grain size are easily regulated, which contribute to the uniform, large grain and non-pinhole perovskite film. Correspondingly, the intrinsic perovskite solar cells based on CH3NH3PbI3 achieve a power conversion efficiency of 17.19% and an average efficiency of 16.25% (std 0.43).