Spatial Control of Nickel Vacancies in Colloidal NiMgO Nanocrystals for Efficient and Stable All-inorganic Quantum Dot Light-Emitting Diodes.
basic_science · Level V
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- Record sourced from PubMed, PMID 39308202.
- Also identified by DOI 10.1002/adma.202410441.
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Abstract
Colloidal quantum dot (QD)-based light-emitting diodes (QD-LEDs) have reached the pinnacle of quantum efficiency and are now being actively developed for next-generation displays and brighter light sources. Previous research has suggested utilizing inorganic hole-transport layers (HTLs) to explore brighter and more stable QD-LEDs. However, the performance metrics of such QD-LEDs with inorganic HTLs generally lag behind those of organic-inorganic hybrid QD-LEDs employing organic HTLs. In this study, colloidal NiMgO nanocrystals (NCs) with spatially controlled Mg are introduced as HTLs for realizing efficient and stable all-inorganic QD-LEDs. During the co-condensation of Ni and Mg precursors to produce valence band-lowered NiMgO NCs, incorporating ≈2% Mg into the NiO lattice creates additional Ni vacancies (V<sub>Ni</sub>) within and on the NCs, influencing the hole concentration and mobility of the NiMgO NC films. Passivating the V<sub>Ni</sub> exposed on the surface with magnesium hydroxide allows for tuning the electrical properties of the NiMgO NCs relative to those of an electron transport layer, allowing for a balanced charge supply and suppressed negative charging of the QDs. Optimized all-inorganic QD-LEDs employing NiMgO NCs achieved a peak external quantum efficiency of 16.4%, peak luminance of 269 455 cd m⁻<sup>2</sup>, and a half-life of 462 690 h at 100 nit.