Optimum temperature of atomic layer deposition of alumina on CsPbBr₃ quantum-dot for optical performance and environmental stability

Atomic layer deposition (ALD) plays a pivotal role in raising the long-term stability of perovskite quantum dot (PQD). The deposition temperature of excellent alumina film prepared by ALD is generally higher than 200 °C. In such a temperature environment, the lattice morphology of PQD is seriously damaged. In this work, to effectively protect PQD, the optimum temperature for depositing alumina on the surface of CsPbBr₃ PQD is investigated. The CsPbBr₃ PQD is deposited on a transparent glass substrate. Subsequently, an alumina layer is deposited on the surface of PQD via ALD at a deposition temperature of 40–120 °C. In our experiment, the significant degradation of PQD is observed when the deposition temperature of ALD is set to 80 °C and above. Lowering the deposition temperature can effectively improve the optical performance of PQD. The samples with alumina deposited at 75 °C show excellent stability after undergoing aging tests, and therefore 75 °C is considered the best ALD temperature. Besides, white light-emitting diode (W-LED) is produced by a method that a stack structure consisting of CsPbBr₃ coated via ALD at 75 °C and CdSe QD is excited using blue Micro-LED, and the color gamut of W-LED accounts for the wide area of 94.00% NTSC (1953) and 86.20% Rec.2020 displayed wide color gamut features. The experiment provides practical guidance for selecting the optimal deposition temperature for ALD-packaged PQD-based devices.