Dual‐Band‐Tunable White‐Light Emission from Bi3+/Te4+ Emitters in Perovskite‐Derivative Cs2SnCl6 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 Cs2SnCl6 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 3P0,1→1S0 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 Cs2SnCl6, but also a general approach to achieve single‐composition white‐light emitters based on lead‐free metal halides through ns2‐metal ion co‐doping. [ABSTRACT FROM AUTHOR]