Perovskite Photovoltaics: The Significant Role of Ligands in Film Formation, Passivation, and Stability

Abstract

Due to their outstanding optoelectronic properties, metal halide perovskites have been intensively studied in recent years. The latest certificated efficiency of 23.3% has recently been achieved in perovskite solar cells (PVSCs), which enables them as a very promising candidate to be used for next-generation photovoltaics. The morphology, defect density, and water resistance, of perovskite films, have an enormous impact on the performance and stability of PVSCs. The ligands, with coordinating capability, have been widely developed to improve the quality and stability of perovskite materials significantly. In the first section of this review, the role of ligand in fabricating perovskite films by different methods (one-step, two-step, and post-deposition treatment) are discussed. In the second section, the progress on ligand-passivated perovskites via post-treatment, in-situ passivation during perovskite formation, and modifying the substrates before perovskite formation is reviewed. In the third section, a discussion of ligand-stabilized perovskite films from the perspectives of crystal crosslinking, dimensionality engineering, and interfacial modification is presented. Finally, a summary and an outlook are given.