Ag/In lead‐free double perovskites

Lead‐free Cs 2 AgInCl 6 and Cs 2 AgInBr 6 double perovskites are studied by a combination of advanced ab‐initio calculations and photoluminescence experiments. 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...