Preparation Of CsPbBr₃/CdS Perovskite Core-shell Quantum Dots And Application Of Optoelectronic Devices

Quantum dots?QDs?are one of the most popular topics in materials in the 21th century.Perovskite QDs,as the leader in the field of QDs,are popular in recent years.Perovskite QDs have excellent optical properties,such as narrow-emission peak,good monochromaticity and high photonluminesce quantum yield,and have great potential for application in various fields.Thus,due to the sensitivity to polar solvents and high temperatures,their further application is limited.And the single halide perovskite QDs have fluorescence intermittency,which further hinders their application in the fields of quantum dot light emitting diode?QLED?,nanolaser,and solid state lighting.In order to overcome the above drawbacks,core-shell structures have been introduced.The formation of core-shell structure between semiconductor is an effective way to enhance the performance of nanocrystals.The synthesis of QDs in core/shell structure is already very mature between binary II-VI nanocrystals.For the cladding between semiconductors and semiconductors,when the band gap of shell is larger than the band gap of core,it can effectively enhance the stability of core QDs in harsh environments.While carriers are prevented from escaping from the surface of QDs,then the non-radiative Auger recombination is suppressed.In order to study the performance of the core-shell structure perovskite and pure perovskite,laser performance and electroluminescent light emitting diode performance based on two QDs were explored.In this paper,the following research work has been specifically done for the above discussion:This article describes the preparation process of CsPbBr₃ perovskite QDs and CsPbBr₃/CdS perovskite QDs and summarizes the chemical reagents and equipment needed for preparation in detail.Two types of QDs were characterized.In order to verify that the coated CsPbBr₃/CdS QDs have higher stability than the pure CsPbBr₃QDs,three groups of contrast experiments were designed for QDs before and after coating,which are temperature stability test,humidity stability test and water resistance test.The experimental results show that the coated CsPbBr₃/CdS QDs exhibit better stability than the pure CsPbBr₃ QDs in both three comparison tests.Next,the optical properties of CsPbBr₃ QDs and CsPbBr₃/CdS QDs were explored.The principle of the inhibition of blinking by introducing CdS nanocrystals was analyzed,and the fluorescence trajectories of two QDs were captured by fluorescence microscopy.The experimental results show that the coated CsPbBr₃/CdS QDs exhibit non-blinking characteristics and are consistent with the theoretical results.For further application of CsPbBr₃/CdS QDs in the field of nanolaser,spontaneous emission amplification tests of CsPbBr₃ QDs and CsPbBr₃/CdS QDs were performed,and the relative efficiency of CsPbBr₃ QDs was increased by 131%.As for the application part,we combined the CsPbBr₃ QDs with the micro-tube resonators and using a single-photon femtosecond laser as the pump source,a whispering gallery mode laser is successfully detected,and the laser exhibits the characteristics of low threshold and high-quality factor.In another work,we fabricated the perovskite QDs based QLED.ITO/ZnO/Mg/QDs/CBP/MoO₃/Al is choosen to be the structure of a perovskite QDs based QLED,in which ITO is a cathode and Al is an anode,and which is an inverted structure.Two QLED devices based on CsPbBr₃ QDs and CsPbBr₃/CdS QDs were characterized respectively by spectrophotometric colorimeter?PR-670?.The experimental results show that the CsPbBr₃/CdS QDs exhibit superior performance in the characterization of each.The CsPbBr₃/CdS based QLED has a lower turn-on voltage and a maximum brightness of 5.4 times that of the pure CsPbBr₃ based QLED.The maximum current efficiency of CsPbBr₃/CdS based QLED is 2.1 times that of the pure CsPbBr₃ based QLED,and the maximum external quantum efficiency is 5.7 times that of the pure CsPbBr₃ QLED.At last,the research work of this paper is summarized and the advantages of the above materials and the high performance of the lasing and QLED based on CsPbBr₃/CdS QDs are pointed out.The further optimization of the core-shell structure coating process and the prospects for the development of core-shell structure perovskite quantum dots are proposed.