Advancements in Solution-Processed Perovskite Solar Cell Surface States and Interface Optimization

Abstract

Perovskite solar cells (PSCs) have shown significant growth in power conversion efficiency, increasing from 3.8% to over 20%. PSCs are chemically similar to dye-sensitized solar cells, using a medium containing hole transporting materials (HTMs) and light-absorbing components to sensitize mesoporous TiO2. However, PSCs are particularly beneficial for photovoltaic applications due to their long photocarrier diffusion lengths and surface states that can serve as recombination sites. Affordable production of PSCs is crucial, and the availability of solution procedures is a critical factor. High PbI2 concentration is essential for better performance, and the high efficiency of PSCs is heavily dependent on surface and interface properties. First-principles computations show that all four surface aspects of tetragonal MAPbI3 have two major phases, with the former being more stable under thermodynamically equilibrium conditions and the latter being vacant- or flat-type terminations. Flat terminations are advantageous for PSC performance in a PbI2-rich environment, as they can amplify the extended carrier lifetime and facilitate hole transport to HTMs.