Lead‐Free Sodium–Indium Double Perovskite Nanocrystals through Doping Silver Cations for Bright Yellow Emission

Abstract

Lead‐free halide perovskite nanocrystals (NCs) have drawn wide attention for solving the problem of lead perovskites toxicity and instability. Here, we successfully synthesize the direct band gap double perovskites undoped and Ag‐doped Cs2NaInCl6 NCs by variable temperature hot injection. The Cs2NaInCl6 NCs have little photoluminescence due to dark self‐trapped excitons (STEs). Interestingly, the dark STEs can be converted to bright STEs by doping Ag+ to produce a bright yellow emission, with the highest photoluminescence quantum efficiency of 31.1%. The dark STEs has been directly observed experimentally by ultrafast transient absorption (TA) techniques. The dynamics mechanism is further study. In addition, the Ag‐doped NCs show better stability than undoped. This result provides a new way to enhance optical properties of lead‐free perovskites NCs for high‐performance light emitters.