Ag/In lead-free double perovskites

Abstract

Lead-free Cs2AgInCl6 and Cs2AgInBr6 double perovskites are studied by a combination of advanced ab-initio calculations and photoluminescence experi-ments. We show that they are insulators with direct band gaps of 2.53 and 1.17 eV, respectively; most importantly, they are characterized by unusually low absorption rates in a ~1 eV wide energy region above the band gap, caused by rather peculiar electronic properties. Consequently, this low absorption conveys very long recombination lifetimes, up to milliseconds at low tempera-ture. Our theoretical analysis suggests that such materials can achieve a good compromise between photoconversion efficiency (above 10%) and visible trans-mittance (above 30%), which makes them potentially suited for lead-free semi-transparent solar cell applications.