Efficient visible and near-infrared luminescence in lanthanide-doped double perovskites via tellurium sensitization

Achieving robust multiband luminescence in metal halide perovskites under blue-light excitation remains challenging due to inefficient energy transfer and weak absorption of lanthanide (Ln 3+ ) ions. Herein, Te 4+ /Ln 3+ (Ln=Er, Ho, Tm, Sm) co-doped Cs 2 NaInCl 6 perovskites were developed as an efficient multiband luminescence material. A unique broadband excitation centered at 435 nm (5s 2 → 5s 1 5p 1 electronic transitions) was introduced through Te 4+ doping, which demonstrates enhanced blue-light compatibility compared to conventional sensitizers such as Sb 3+ /Bi 3+ . Systematic investigations reveal that self-trapped excitons generated in [TeCl 6 ] 2− octahedrons act as efficient energy donors, enabling broadband sensitization of Ln 3+ ions. The optimized Te 4+ /Ln 3+ codoped systems exhibit characteristic multiband emissions spanning both visible and near-infrared (NIR) wavelengths under 435 nm excitation, achieving NIR photoluminescence quantum yields of 10.26% for Te 4+ /Tm 3+ (1223 nm emission) and 9.36% for Te 4+ /Er 3+ (1540 nm emission). These findings establish Cs 2 NaInCl 6 :Te 4+ /Ln 3+ as a versatile optoelectronic platform, combining blue-LED-driven multicolor emission with exceptional stability for practical applications.