Interface Engineering of CsPbBr<sub>3</sub> Nanocrystal Light‐Emitting Diodes via Atomic Layer Deposition
Binze Zhou, Zhaojie Wang, Shicai Geng, Yun Li, Kai Wang, Kun Cao, Yanwei Wen, Rong Chen
Abstract
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 Al 2 O 3 infilling and interface engineering for the CsPbBr 3 nanocrystal emission layers, and the inorganic electron transport layer‐based CsPbBr 3 –ZnMgO LED device is fabricated. The introduction of Al 2 O 3 ALD layers significantly improves the tolerance of CsPbBr 3 PNC thin films to polar solvents ethanol of ZnMgO during spin coating. The operation lifetime of ALD‐treated CsPbBr 3 PNC–ZnMgO LED is prolonged to about two orders of magnitude greater than that of the CsPbBr 3 PNC‐TPBi LED device with a largely improved external quantum efficiency (EQE) value. Moreover, the infilling of Al 2 O 3 into the CsPbBr 3 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 Al 2 O 3 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 Al 2 O 3 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.