Identification and Remedy of Defect States in Quantum Dot Electroluminescent Devices
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Colloidal quantum dot-based light-emitting diodes (QD-LEDs) have rapidly advanced in peak efficiency and brightness, paving the way for next-generation lighting devices, including augmented and virtual reality displays This presentation focuses on various defects in QD-LEDs and remedies for realizing efficient and stable all-inorganic devices. We found zinc vacancies in QDs acting as hole traps, but compressive strain developed by the outermost shell can deactivate their involvement in exciton recombination process. Meanwhile, in NiO-based hole transport layers (HTLs), nickel vacancies significantly affect carrier transport and charge transfer at QD-HTL interfaces. Chemical passivation of nickel vacancies allowed for optimizing hole concentration and mobility with respect to the electron transport layer. Comprehensive defect management in all-inorganic QD-LEDs demonstrated a record efficiency of 16.3% and peak brightness over 200,000 nits.