Air stable and highly efficient Bi³⁺-doped Cs₂SnCl₆for blue light-emitting diodes

Cs₂SnCl₆perovskite has recently attracted attention as a promising optoelectronic material owing to its better stability and reduced toxicity than its lead counterparts. However, its luminescence performance hardly satisfies the requirements. Hence, a series of Bi³⁺-doped Cs₂SnCl₆(Cs₂SnCl₆:Bi³⁺) with enhanced luminescence were synthesized by a solution-phase route. The results show that the initial concentration of Sn²⁺can adjust the nucleation density and the quality of the crystal nucleus growth, which will affect the Bi³⁺doping amount, crystal morphology, and photophysical properties of Cs₂SnCl₆:Bi³⁺. Cs₂SnCl₆:Bi³⁺shows excellent stability in the atmosphere with a photoluminescence (PL) of around 456 nm and a photoluminescence quantum yield (PLQY) of 31%. The luminescence performance results from [Bi_Sn4+³⁺+ V_Cl] defects caused by the Bi³⁺doping. The blue LED based on the Cs₂SnCl₆:Bi³⁺phosphor exhibits a long life of about 120 h and a Commission Internationale de L'Eclairage (CIE) color coordinates of (0.14, 0.11). This work demonstrates a strategy for Bi-doped perovskites with good stability. This investigation will facilitate the development of Cs₂SnCl₆:Bi³⁺for blue LED applications.