Tunable efficient visible and near-infrared multi-emission in Ho3+ doped Cs2NaBiCl6 double perovskite via Ag+ alloying

Herein, we successfully obtained Ho 3+ and Ag +  -codoped Cs 2 NaBiCl 6 halide double perovskites (DPs) via a hydrothermal method , which exhibit orange-red broadband self-trapped excitons (STE) emission and visible (Vis) and near-infrared (NIR) narrow band emission attributed to Ho 3+ f-f transition, under 360 nm excitation. Compared to the single Ho 3+ -doped sample, the Vis PL intensity of the codoped sample was increased by nearly 13.8 times, and an enhanced photoluminescence quantum yield (PLQY) of 87.45 % was achieved. The PL enhancement is attributed to the partial substituting of Na + with Ag + , leading to an efficient STE emission, and the more energy transition from STE to Ho 3+ . Moreover, the synthesized phosphor exhibits good stability in thermal and atmospheric environments. White light-emitting diode (WLED) is fabricated by employing Cs 2 Na 0·997 Ag 0·003 Bi 0.935 Ho 0.065 Cl 6 on near-ultraviolet (n-UV) LED chips, achieving a color rendering index (CRI) of 95.0 and correlated color temperature (CCT) of 3814 K. Anti-counterfeit patterns and the application for night vision monitoring were also discussed. This study inspires the designing of high-quality phosphors of rare earth-doped DPs and expands the multi-domain luminescence applications of halide DPs.