Ionic liquid-assisted perovskite crystal film growth for high performance planar heterojunction perovskite solar cells

Abstract

We demonstrate an efficient approach by using a new type of ionic liquid, 1-ethylpyridinium chloride (1-EC) with a relative low melting point of 100 °C, to control the morphological growth of CH₃NH₃PbI₃ during the one-step deposition method for preparing efficient planar heterojunction perovskite solar cells, leading to a continuous and dense morphology without large voids and pinhole. With the optimized concentration, 11.8% power conversion efficiency was obtained. Our work paves the way to optimize the morphology of perovskite by adopting a new kind of ionic liquid as additive. This method has great benefits for exploiting new technologies for large-scale perovskite solar cells on the flexible substrate.