Interface Engineering of CsPbBr₃ Nanocrystal Light‐Emitting Diodes via Atomic Layer Deposition

Perovskite nanocrystal (PNC) suffers from solution corrosion and water/oxygen oxidation when used in light‐emitting diodes (LEDs). Atomic layer deposition (ALD) is applied to introduce Al₂O₃ infilling and interface engineering for the CsPbBr₃ nanocrystal emission layers, and the inorganic electron transport layer‐based CsPbBr₃–ZnMgO LED device is fabricated. The introduction of Al₂O₃ ALD layers significantly improves the tolerance of CsPbBr₃ PNC thin films to polar solvents ethanol of ZnMgO during spin coating. The operation lifetime of ALD‐treated CsPbBr₃ PNC–ZnMgO LED is prolonged to about two orders of magnitude greater than that of the CsPbBr₃ PNC‐TPBi LED device with a largely improved external quantum efficiency (EQE) value. Moreover, the infilling of Al₂O₃ into the CsPbBr₃ layer boosts the carrier mobility for more than 40 times inside the light‐emission layer. However, the interfacial carrier transport between different functional layers is hindered by the insulated Al₂O₃ layer, which provides an effective barrier for excess electron transport. Such a favorable band alignment facilitates the carrier balance of the device and contributes to the improved electroluminescent performance of the device with ALD Al₂O₃ interface engineering, which is further supported by theoretical device modeling. Herein, a facile method is provided to fabricate PNC‐LED devices with both high efficiency and long‐term lifetime.