High efficiency near-infrared light emission and ultra-high stability of the lead-free double perovskite Cs2Na1−xAgxBi1−yAlyCl6

Abstract

Environmentally friendly lead-free double perovskites with good stability can solve the problems of toxicity and instability of lead halide perovskites and can be a powerful substitute for them. In this study, Cs₂Na_1−xAg_xBi_1−yAl_yCl₆ perovskite powders co-doped with Ag⁺ and Al³⁺ were synthesized using a simple hydrothermal method. They can emit bright and wide near-infrared light, with the center at 715 nm, and the photoluminescence quantum yield is as high as 48.6%. This bright emission results from the combined modification effects of self-trapped exciton (STE) formation, carrier incorporation by Ag⁺ and the carrier spatial confinement by the Al ions on the indirect band of Cs₂NaBiCl₆. In addition, Cs₂Na_1−xAg_xBi_1−yAl_yCl₆ also shows ultra-high structural stability and good thermal stability with a melting point of up to 600 °C. Our work not only opens up a new way for the design of efficient and stable near-infrared light-emitting materials with an atomic level confining modification, but also may have great applications in the fields of optical communication and quantum storage, as well as in near-infrared detection of the human body.