Study Of CsPbBr₃ Quantum Dots Stabilization Via Atomic Layer Deposition

As a kind of semiconductor nanoparticle,quantum dots have good absorption properties,high quantum yield,narrow emission half-width,long carrier diffusion length and excellent multi-exciton effect.These excellent properties make quantum dots have excellent application prospects in the field of optoelectronic devices.However,the biggest problem that currently restricts the practical use of quantum dots optoelectronic devices is the stability of the device.Atomic layer deposition?ALD?as a self-limiting sub-nano-scale controllable thin film growth technology,the growth of the film has a high degree of compactness,uniformity and consistency.At present,there are few applications about the application of ALD technology to the stabilization and surface modification of quantum dot particles,and there are few studies on the interaction mechanism between ALD precursors and quantum dots surface ligands.In our research,based on the atomic layer deposition technique,the typical alumina?TMA,H₂O?ALD deposition process is used to represent the relationship of the interaction between the ALD precursor and the surface of CsPbBr₃ quantum dots with the performance of CsPbBr₃ quantum dots.The CsPbBr₃ quantum dot/silica microspheres were prepared,and the alumina film was then deposited on the surface of the quantum dot/silica microspheres to passivate the quantum dot defect surface,which improved the stability and optical performance of the quantum dots in actual use.The main research of this paper is divided into the following sections:1.By analyzing the changes of the optical performance of quantum dots at different ligand types and different ligand concentrations on the surface of CsPbBr₃ perovskite quantum dots.The relationship between the performance of CsPbBr₃ quantum dots and common oleic acid?oleyl amine?is founded.The interaction between precursor and ligand in alumina ALD process was preliminarily investigated by FTIR.The relationship between the ALD growth process and the number of cycles was preliminarily studied by QCM and the performance of quantum dots in the ALD process was improved by adding DDAB ligands.2.By preparing the quantum dot/silica composite microspheres,the stability and dispersibility of the CsPbBr₃ quantum dots are initially improved,and the CsPbBr₃ quantum is greatly improved by depositing an aluminum oxide film on the surface of the quantum dots microspheres.By combining XPS,XRD and TR-PL transient spectroscopy,the valence state changes,crystal structure changes and surface defects of CsPbBr₃ quantum dots before and after ALD deposition were analyzed in detail.Finally,the mechanism of quantum dot stabilization via ALD method is investigated.