Efficient and bright broadband electroluminescence based on environment-friendly metal halide nanoclusters
Dingshuo Zhang, Meiyi Zhu, Yifan He, Qingli Cao, Yun Gao, Hongjin Li, Guochao Lu, Qiaopeng Cui, Yong‐Miao Shen, Haiping He, Xingliang Dai, Zhizhen Ye
Abstract
Abstract Broadband electroluminescence based on environment-friendly emitters is promising for healthy lighting yet remains an unprecedented challenge to progress. The copper halide-based emitters are competitive candidates for broadband emission, but their high-performance electroluminescence shows inadequate broad emission bandwidth of less than 90 nm. Here, we demonstrate efficient ultra-broadband electroluminescence from a copper halide (CuI) nanocluster single emitter prepared by a one-step solution synthesis-deposition process, through dedicated design of ligands and subtle selection of solvents. The CuI nanocluster exhibits high rigidity in the excitation state as well as dual-emissive modes of phosphorescence and temperature-activated delayed fluorescence, enabling the uniform cluster-composed film to show excellent stability and high photoluminescent efficiency. In consequence, ultra-broadband light-emitting diodes (LEDs) present nearly identical performance in an inert or air atmosphere without encapsulation and outstanding high-temperature operation performance, reaching an emission full width at half maximum (FWHM) of ~120 nm, a peak external quantum efficiency of 13%, a record maximum luminance of ~50,000 cd m −2 , and an operating half-lifetime of 137 h at 100 cd m −2 . The results highlight the potential of copper halide nanoclusters for next-generation healthy lighting.