Dual-Band-Tunable White-Light Emission from Bi3+ /Te4+ Emitters in Perovskite-Derivative Cs2 SnCl6 Microcrystals.

Luminescent metal halides have attracted considerable attention in next-generation solid-state lighting because of their superior optical properties and easy solution processibility. Herein, we report a new class of highly efficient and dual-band-tunable white-light emitters based on Bi3+ /Te4+ co-doped perovskite derivative Cs2 SnCl6 microcrystals. Owing to the strong electron-phonon coupling and efficient energy transfer from Bi3+ to Te4+ , the microcrystals exhibited broad dual-band white-light emission originating from the inter-configurational 3 P0,1 →1 S0 transitions of Bi3+ and Te4+ , with good stability and a high photoluminescence (PL) quantum yield of up to 68.3 %. Specifically, a remarkable transition in Bi3+ -PL lifetime from milliseconds at 10 K to microseconds at 300 K was observed, as solid evidence for the isolated Bi3+ emission. These findings provide not only new insights into the excited-state dynamics of Bi3+ and Te4+ in Cs2 SnCl6 , but also a general approach to achieve single-composition white-light emitters based on lead-free metal halides through ns2 -metal ion co-doping.