Tunable Dual Emission in Bi 3+ /Te 4+ -Doped Cs 2 HfCl 6 Double Perovskites for White Light-Emitting Diode Applications.

Multicolor-emission-based single-phase white light derived from different luminescence centers is an effective way to manipulate the optical properties of halide perovskites. In this work, we developed a codoping strategy to incorporate Bi 3+ and Te 4+ emission centers into all-inorganic lead-free Cs 2 HfCl 6 perovskite by a hydrothermal method. The as-prepared Bi 3+ /Te 4+ -doped Cs 2 HfCl 6 microcrystals show bright blue (Bi 3+ ), yellow (Te 4+ ), and warm-white emissions (Bi 3+ /Te 4+ ), respectively. The broad efficient dual emission in Bi 3+ /Te 4+ co-doped Cs 2 HfCl 6 is assigned to the typical 3 P 1 → 1 S 0 transition emission from Bi 3+ originating from [Bi Hf + V Cl ] and self-trapped excitons (STEs) from Te 4+ . Moreover, the concentration-optimized Cs 2 HfCl 6 :Te 4+ shows excellent antiwater stability and high photoluminescence quantum yield (PLQY) of ∼70%. Meanwhile, a white light-emitting diode (WLED) fabricated using Bi 3+ /Te 4+ co-doped Cs 2 HfCl 6 is close to warm white with a color rendering index (CRI) of 75.4, CIE color coordinate of (0.370, 0.393), and a correlated color temperature (CCT) of 4380 K. These results suggest that Bi 3+ /Te 4+ co-doped all-inorganic lead-free Cs 2 HfCl 6 is a potential single-phase white light-emitting phosphor candidate for solid-state lightings.