Bi3+/Te4+ Co-Doping Achieves Dual-Band-Tunable White-Light Emission in Perovskite-Derivative Microcrystals

All-inorganic lead-free luminescent metal halides doped with ns²-metal ions have displayed great promise in next-generation solid-state lighting owing to their superior optical properties and easy solution processibility.

However, the photoluminescence (PL) origin of ns²-metal ion-doped metal halides is unknown, and many recent studies have attributed it to the misinterpreted self-trapped exciton (STE) emission. Furthermore, due to a lack of suitable luminescent centers that allow for efficient energy transfer (ET) with minimal energy loss, achieving efficient and tunable white-light emission in metal halides remains difficult.

The research group led by Professor Xueyuan Chen from the Chinese Academy of Sciences’ Fujian Institute of Research on the Structure of Matter developed a new class of extremely effective and dual-band-tunable white-light emitters based on Bi³⁺/Te⁴⁺co-doped perovskite derivative Cs₂SnCl₆ microcrystals (MCs). The research was in Angewandte Chemie International Edition.

The Bi³⁺ and Te⁴⁺ ions in singly-doped MCs exhibited intense blue and yellow PL originating from the inter-configurational ³P_0,1→¹S₀ transitions at 456 and 565 nm with large Stokes shifts, broad emission bands, and high PL quantum yields (QYs) of 60.6% and 84.6%, respectively, due to strong electron-phonon coupling in the spatially confined 0D structure of Cs₂SnCl₆.

Due to the strong temperature dependence of the spin-forbidden ³P₀→¹S₀ and spin-orbital allowed ³P₁→¹S₀ transitions of Bi³⁺, the authors discovered a spectacular transition in the PL lifetime from 1.20 ms at 10 K to 1.49 μs at 300 K in Cs₂SnCl₆: 1.1% Bi³⁺, as solid evidence for the isolated Bi³⁺ emission.

Furthermore, they achieved dual-band-tunable white-light emissions in Cs₂SnCl₆: Bi³⁺/Te⁴⁺MCs with excellent structure-, air-, photo- and anti-water stability and a PLQY of up to 68.3% through efficient ET from Bi³⁺ to Te⁴⁺.

This research adds to the understanding of Bi³⁺ and Te⁴⁺ excited-state dynamics in Cs₂SnCl₆, as well as a general approach to achieving single-composition white-light emitters based on lead-free metal halides using ns²-metal ion co-doping.

Journal Reference:

Zhang, W., et al. (2022) Dual-Band-Tunable White-Light Emission from Bi³⁺/Te⁴⁺ Emitters in Perovskite-Derivative Cs₂SnCl₆ Microcrystals. Angewandte Chemie International Edition. doi.org/10.1002/anie.202116085.