Boosting Energy Transfer from Self‐Trapped Exciton to Er3+ Through Sb3+ Doping in Cs2Na(Lu/Er)Cl6 Double Perovskites

Abstract

AbstractMetal halide double perovskites are highly attractive for optoelectronic applications because of their superior optical properties. Here, a novel halide double perovskite, Cs2NaLuCl6, exhibiting bright blue emission originating from the host self‐trapped exciton (STE) is reported. Through doping with Sb3+, the dopant‐induced STE is formed in the crystals with a photoluminescence quantum yield up to 94%. The energy transfer from the dopant STE to Er3+ is superior to the direct excitation of Er3+, which is more efficient than the energy transfer from the host STE to Er3+. Furthermore, the energy transfer efficiency from STE to Er3+ is boosted from 8% to 33% through Sb3+ doping in Cs2NaLu0.95Er0.05Cl6. Due to the strong electron‐phonon coupling and efficient energy transfer, the as‐prepared crystals exhibit intense dual‐band emissions and remarkable thermal stability. Importantly, the STE emission variation after the Er3+‐substitution is explored based on the electron‐phonon coupling effect. These findings provide new insights into the excited state dynamics of halide double perovskites and extend their luminescence applications such as white light‐emitting diodes and night vision.