Synthesis,luminescence Properties And Stabilization Of Highly Stable Perovskite Quantum Dots/alumina Composites

In recent years,perovskite quantum dots stand out for their excellent photoelectric properties among all kinds of optoelectronic materials.Compared with organic-inorganic hybrid perovskite quantum dots,all-inorganic perovskite quantum dots?IPQDs?show higher chemical stability.All-inorganic perovskite quantum dots have aroused tremendous interest owing to their high absorption coefficient,narrow full-width at half maximum,high photoluminescence quantum yield?PLQY?,controllable composition and size,tunable emission spectrum,photoluminescence and electroluminescence dual characteristics.These excellent properties have made all-inorganic perovskite quantum dots become one of the most promising optoelectronic materials,and widely used in light emitting diodes?LEDs?,solar cell,photodetector,laser and other fields.Unfortunately,there still exist many problems in all-inorganic perovskite quantum dots.1.The luminescence mechanism of all-inorganic perovskite quantum dots is not clear enough.A large number of comprehensive and systematic studies are still needed to reveal the mechanism for their excellent photoelectric performance.2.The photoluminescence quantum yield of the CsPbCl₃ quantum dots is low and needs to be further improved.3.Pb in all-inorganic perovskite quantum dots is toxic.Further analysis of the impact of Pb in all-inorganic perovskite quantum dots should be carry out so as to lay a theoretical foundation for development of lead-free or lead-less quantum dots materials.4.Further optimization of preparation process is required for the sake of adapting to large-scale production.5.Long chain insulation ligands on the surface of quantum dots hinder the charge-transfer between crystal grains.On the premise of sufficient passivation of quantum dots surface,an effective way to develop highly efficient LEDs is to minimize the hindrance of ligands to charge transfer.6.All-inorganic perovskite quantum dots are unstable,and they are easy to decompose or agglomerate in polar solvents.The all-inorganic perovskite quantum dots,especially CsPbI₃ quantum dots,exhibit poor stability to light,oxygen,high humidity and temperature.Anion exchange can occur easily when different all-inorganic perovskite quantum dots are mixed.In this paper,the stability problem to be solved is studied and some progress has been made.All-inorganic perovskite quantum dots was synthesized by high temperature hot injection method,and their luminescence properties were controlled by controlling the reaction temperature and halogen composition.In addition,a series of oxide/quantum dot composites were prepared by in situ adsorption.The structure and morphology of all-inorganic perovskite quantum dots and composites were characterized by X-ray diffraction?XRD?,field emission scanning electron microscope?FE-SEM?and transmission electron microscope?TEM?.The luminescence properties of all-inorganic perovskite quantum dots and composites were studied by using photoluminescence quantum yield,steady-state and time-resolved spectra.In addition,their luminescence thermal stability was studied by variable temperature spectra.Among them,both dendritic silica/quantum dots and hierarchicalalumina/quantumdotcompositesshowsignificant improvement in thermal stability.In addition,the Al₂O₃/CsPbBr₃composites exhibit a high photoluminescence quantum yield?PLQY?of80%and dramatically improved stability against destruction by water and heat.Further,density functional theory calculations reveal that significant charge transfer between CsPbBr₃ and Al₂O₃ surface leads to enhanced electrostatic adherence of the two parts and internal stability improvement of the CsPbBr₃.These findings are expected to shed light on further understanding and design of novel perovskite composites for stable,tunable optoelectronic devices.