Lead-Free Alloyed Double Perovskites: An Emerging Class of Materials for Optoelectronic Applications

Abstract

Lead-free all-inorganic alloyed double perovskites have redefined the photovoltaic research in the recent past. However, a detailed study of their optical, excitonic, polaronic, and transport properties remains unexplored. Here, we investigate the variation of carrier-lattice interaction and optoelectronic properties of pristine as well as alloyed Cs2AgInCl6 double perovskites using a combined state-of-the-art many-body perturbation theory and density functional perturbation theory. Our results reveal that, in comparison to a pristine material, alloyed compounds have a longer exciton lifetime, indicating a lower electron–hole recombination in the latter. This also leads to a higher quantum yield and conversion efficiency in the alloyed compounds. The phonon scattering is found to limit the charge carrier mobilities and, thus, plays an important role in the development of high-efficiency perovskite photovoltaics. Dominant carrier-phonon scattering is also observed via the Fröhlich mechanism near room temperature. A significant increase in hole and electron mobilities is noticed in alloyed perovskites in comparison to its pristine counterpart making the former more potent in photovoltaic devices.