Chapter 4: Photophysics of Hybrid Perovskites

Hybrid perovskites are an emergent class of materials for optoelectronic applications. The understanding of their photophysics is however lagging behind, hampering the systematic engineering of best performing devices. Disentangling the different photophysical contributions and identifying the intrinsic properties are in demand for a market-scale development of this technology. In this book chapter, we provide the physical basis for the optical properties of these semiconductors. We will focus in particular on the absorption and emission properties of methyl-ammonium lead iodide (CH₃NH₃PbI₃), which is the active semiconductor of the champion solar cells, as well as CH₃NH₃PbBr₃. We will discuss specific photophysical observables and phenomena, such as the bandgap, the carrier lifetime, the trapping dynamics, the carrier diffusion/mobility and the Coulomb correlation effects. Attention will be paid to the role of the microstructure on the photophysics of the material. We will also review various experimental methods used until now to perform photophysical investigations on perovskites, and we will highlight the cautionary steps to be kept in mind while employing such techniques.