Nanoparticle-induced fast nucleation of pinhole-free PbI2 film for ambient-processed highly-efficient perovskite solar cell

Abstract Fully ambient, low temperature-processed, and high-performance perovskite solar cells (PSCs) fabricated with sequential deposition method (SDM) are especially attractive for future commercialization. However, it is extremely difficult as uncontrollable crystallization of PbI 2 upon deposition is usually induced by moisture under atmospheric conditions. Here, we report a nanoparticle-induced fast nucleation (NIFN) method to improve the quality of fully ambient-processed PbI 2 layer. In particular, ZnO nanoparticles (NPs) are added into the lead iodide solution as growth controlling agents to obtain pinhole-free PbI 2 layer, leading to pinhole-free MAPbI 3 (methylammonium lead iodide) layer. As compared to the control devices, the devices made of pinhole-free MAPbI 3 film show an improvement of power conversion efficiency (PCE) over 20%. Moreover, an ambient-processed PSC by using this simple method shows a record PCE up to 18.3%. Our work not only reveals the origin of the morphology PbI 2 and its effect on MAPbI 3 film formation in ambient air, but demonstrates a simple and unique method to boost ambient-processed high-performance PCSs for potential industrial use.