Pressure-Induced Distinct Self-Trapped Exciton Emission in Sb³⁺-Doped Cs₂NaInCl₆ Double Perovskite

Abstract

The Cs2NaInCl6 double perovskite is one of the most promising lead-free perovskites due to its exceptional stability and straightforward synthesis. However, it faces challenges related to inefficient photoluminescence. Doping and high-pressure are employed to tailor the optical properties of Cs2NaInCl6. Herein, Sb3+ doped Cs2NaInCl6 (Sb3+:Cs2NaInCl6) was synthesized and exhibits blue emission with a photoluminescence quantum yield of up to 37.3%. Further, by employing pressure tuning, a blue stable emission under a very wide range from 2.7 GPa to 9.8 GPa, for the first time, realized in Sb3+:Cs2NaInCl6. Subsequently, the emission intensity of Sb3+:Cs2NaInCl6 experiences a significant increase (3.3-times) at 19.0 GPa. We reveal that the pressure-induce the distinct emissions can be attributed to the carrier self-trapping and detrapping between Cs2NaInCl6 and Sb3+. Notably, the lattice compression in the cubic phase inevitably modify the band gap of Sb3+:Cs2NaInCl6. Our findings provide valuable insights into the effects of the high pressure in further boosting unique emission characteristics but also offer promising opportunities for the development of doped double perovskites with enhanced optical functionalities.