The phototransport in halide perovskites: From basic physics to applications

There is at present an intensive, wide, and growing interest in the phototransport properties of Halide Perovskites (HaPs) that follows their recent discovery as promising materials for efficient and easy to fabricate solar cells. However, the basic physics of the exceptional superior performance of these cells is still a puzzle. In the present work, we suggest a solution to the puzzle and show that the exceptional performance of those cells is due to the special-rare scenario of shallow centers that dominate the recombination process in the HaPs (in addition to the obvious efficient light absorption). Our analysis provides a general new extension of the classical theory of phototransport and an elucidation of the physical essence of the operation of p-i-n solar cells. This extension is based on the Shockley-Read (SR) recombination model for the simple, single-level kind of recombination centers. In this article, we show that the latter understanding is very beneficial for future improvements in the design and fabrication of HaP-based solar cells, beyond their present configurations. In particular, we explain why and how various annealing procedures can improve the solar energy conversion of the corresponding solar cells. We further suggest that an all-perovskite-all-vacuum-deposited solar cell is feasible and promising for the upscaling of the HaPs cells' technology.