Tunable Dual Emission in Bi3+/Te4+-Doped Cs2HfCl6 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 Bi3+ and Te4+ emission centers into all-inorganic lead-free Cs2HfCl6 perovskite by a hydrothermal method. The as-prepared Bi3+/Te4+-doped Cs2HfCl6 microcrystals show bright blue (Bi3+), yellow (Te4+), and warm-white emissions (Bi3+/Te4+), respectively. The broad efficient dual emission in Bi3+/Te4+ co-doped Cs2HfCl6 is assigned to the typical 3P1 → 1S0 transition emission from Bi3+ originating from [BiHf + VCl] and self-trapped excitons (STEs) from Te4+. Moreover, the concentration-optimized Cs2HfCl6:Te4+ shows excellent antiwater stability and high photoluminescence quantum yield (PLQY) of ∼70%. Meanwhile, a white light-emitting diode (WLED) fabricated using Bi3+/Te4+ co-doped Cs2HfCl6 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 Bi3+/Te4+ co-doped all-inorganic lead-free Cs2HfCl6 is a potential single-phase white light-emitting phosphor candidate for solid-state lightings.