Band-Like Charge Transport in Cs2AgBiBr6 and Mixed Antimony?Bismuth Cs2AgBi1?xSbxBr6 Halide Double Perovskites

摘要

Recently, halide double perovskites (HDPs),such as Cs2AgBiBr6, have been reported as promising nontoxicalternatives to lead halide perovskites. However, it remainsunclear whether the charge-transport properties of thesematerials are as favorable as for lead-based perovskites. In thiswork, we study the mobilities of charges in Cs2AgBiBr6 and inmixed antimony?bismuth Cs2AgBi1?xSbxBr6, in which theband gap is tunable from 2.0 to 1.6 eV. Using temperaturedependent time-resolved microwave conductivity techniques,we find that the mobility is proportional to T?p (with p ≈1.5). Importantly, this indicates that phonon scattering is thedominant scattering mechanism determining the chargecarrier mobility in these HDPs similar to the state-of-the-artlead-based perovskites. Finally, we show that wet chemical processing of Cs2AgBi1?xSbxBr6 powders is a successful route toprepare thin films of these materials, which paves the way toward photovoltaic devices based on nontoxic HDPs with tunableband gaps.