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

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 it 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 is realized in Sb3+:Cs2NaInCl6. Subsequently, the emission intensity of Sb3+:Cs2NaInCl6 experiences a significant increase (3.3 times) at 19.0 GPa. It is revealed that the pressure-induced 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 modifies the band gap of Sb3+:Cs2NaInCl6. Our findings provide valuable insights into effects of the high pressure in further boosting unique emission characteristics but also offer promising opportunities for development of doped double perovskites with enhanced optical functionalities.