Although all-inorganic lead-free metal halides exhibit considerable potential for optoelectronic applications, achieving high-performance 1540 nm near-infrared (NIR) emission in these systems is a significant challenge. Herein, we demonstrate a codoping strategy utilizing Bi3+ and Er3+ ions to enable enhanced 1540 nm NIR luminescence in vacancy-ordered Cs2SnCl6 double perovskite phosphors compatible with commercial near-ultraviolet LED excitation sources. By leveraging the spin-orbit permitted 1S0 → 3P1 transition of Bi3+ as an effective sensitization pathway, we successfully activated the NIR emission band corresponding to the Er3+ 4I13/2-4I15/2 electronic transition. The optimized phosphor achieved a notable quantum efficiency of 10.3% for the Er3+-derived NIR emission. Moreover, the Er3+ 1540 nm emission exhibits excellent stability over six months, retaining 92.5% of their initial PL intensity. Finally, we fabricated NIR phosphor-converted LEDs based on Bi3+- and Er3+-codoped Cs2SnCl6 and successfully applied them to night imaging. This work expands the application potential of the Cs2SnCl6 matrix, paving the way for its development as a near-infrared phosphor for advanced optoelectronic applications.
Zhang et al. (Thu,) studied this question.