Optical responses of lead halide perovskite semiconductors

Halide perovskites are a promising class of semiconductors with outstanding optical properties. They are considered to be superior materials for conversion between light and electrical energy, and efficient conversion in both directions has been demonstrated with solar cell and light-emitting diode devices based on halide perovskites. The high device performances have been attributed to materials properties such as exceptionally low densities of defects formed within the bandgap of these materials and extremely high photoluminescence (PL) quantum efficiencies even at room temperature. In this topical review, we present recent advances in understanding of the photophysics of lead halide perovskites and discuss several practically important aspects of these semiconductors; the controllability of optical properties by halogen substitution, the anti-Stokes PL as a result of strong electron–phonon interactions, and temperature dependences of the PL spectrum, the longitudinal-optical phonon spectrum, and the refractive index.