Potassium Iodide Passivation Enabling Performance Improvement of CsCu₂I₃-Based LEDs

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Ternary copper halide CsCu_ 2I_ 3emerges as a highly promising candidate for eco-friendly light-emitting diodes (LEDs), but the electroluminescent performance is limited by defect-related nonradiative losses and disordered crystallization. Herein, we develop a potassium iodide (KI)-modified engineering of CsCu_ 2I_ 3emitters to passivate the defects by compensating for any halide vacancies, and reduce trap state density. Meanwhile, this strategy can optimize the crystallization process of CsCu_ 2I_ 3to obtain continuous high-quality CsCu_ 2I_ 3films, which is conductive to suppressing leakage current of corresponding devices. Benefitting from the suppression of nonradiative recombination due to the reduced halide vacancies, and improved film morphology of CsCu_ 2I_ 3by optimizing the crystallization process of CsCu_ 2I_ 3, the EQE of corresponding LED is largely improved from 0.02% to 0.065%. The results highlight the great potential of KI passivation for high performance eco-friendly CsCu_ 2I_ 3based LED.