Achieving a near-unity quantum yield from yellow emitting metal halide double perovskites toward human-centric warm white LED lighting

The use of LED lighting results in a prolonged exposure to blue radiation, which is harmful to the human eye health. Herein, a new strategy aiming for "human-centric" lighting is demonstrated by doping Te4+ into Cs2HfCl6, leading to zero blue radiation through mixing red and green phosphors in a NUV-LED chip. Cs2HfCl6:Te yields an efficient bright yellow emission with a high photoluminescence quantum efficiency of 95.26%. Surprisingly, the emission intensity maintains 96% of its initial value even when the post-annealing temperature is as high as 450 degrees C, demonstrating superior thermal resistance. Moreover, excellent environmental stability is achieved via a silane coupling agent to modify the surface, and the broadband yellow emission intensity remains at 91% of the initial strength after soaking in water for 100 min and hardly changes after 120 h of storage in air. A packaging device using a 395 nm LED chip, Cs2HfCl6:0.5%Te, and green and red-emitting phosphors produces warm white light with a high color rendering index, while significantly eliminating blue radiation. These results demonstrate that Cs2HfCl6:Te perovskite is a promising phosphor with the capability of advancing human-centric lighting.