Construction Of Perovskite Quantum Dots Composites And Study On Their Photoelectric Stability

In recent years,because of the excellent optical properties of perovskite quantum dots(PQDs)such as extremely high fluorescence quantum efficiency,narrow emission peak half-peak width,and tunable emission spectral range.PQDs have been widely used in lighting and display field,showing a strong potential to replace traditional quantum dots and organic rare-earth fluorescent materials.However,the poor stability of PQDs severely limits the application of PQDs.Water in humid air,high temperature and light irradiation may lead to the shedding of PQDs ligands,accompanied by the collapse of the PQDs structure,the light conversion ability is gradually lost,and its excellent optical properties are difficult to translate into practical applications.In the field of display lighting,PQDs need to face a complex environment,which is difficult to store and process easily.At the same time,they have to face the high temperature brought by long-term power-on,and their structure faces the risk of collapse,which is easy to cause them to agglomerate with each other.The degradation will eventually lead to the shift of the emission peak,which greatly affects the long-term working performance of the device.Therefore,how to prepare highly stable PQDs composite materials and improve the stability of PQDs in complex environments will help to broaden their application scenarios.This dissertation mainly investigates the construction of encapsulating PQDs in various organic or inorganic matrices to provide protection for PQDs in complex environments,improve their poor stability defects,and retain their excellent optical properties.First,CH3NH3PbBr3 PQDs were encapsulated by ethyl cellulose(EC),and a sandwich structure packaging process was proposed to prepare EC-CH3NH3PbBr3 PQDs composites with a thickness of about 70 μm.The film material retains the excellent optical properties of PQDs,and at the same time has strong waterproof performance,shields the erosion effect of water on PQDs.And as a solar cell packaging film material,with the help of the down-conversion luminescence function of PQDs broadens the spectral response range of crystalline silicon solar cells and improves the photoelectric conversion efficiency.Further,an innovative one-step strategy for preparing EC-PQDs composite films with emission light covering the full spectral range is proposed.The core of this method lies in the simultaneous use of toluene as a poor solvent for PQDs in the ligand-assisted precipitation method.It can also be used as a good solvent for EC.PQDs can be directly generated inside cellulose and encapsulated into a film,which prevents the loss of optical properties of PQDs by water in long-term immersion experiments.The application of the film as the luminescent material of monochromatic light LED,and the application prospect of PQDs in the field of flexible display is explored.Secondly,in this paper,hexagonal boron nitride(h-BN)material with twodimensional layered structure is used to obtain h-BN/CH3NH3PbBr3 PQD nanocomposites by ligand-assisted precipitation at low temperature.In this study,hBN endows PQDs with the ability to stably preserve in high temperature environments by virtue of its high stability,large specific surface area and excellent thermal conductivity.The application potential of this composite material in the field of lighting display is proved.Subsequently,in this paper,ZrSi/CH3NH3PbX3 and ZrSi/CsPbX3 PQD composites with high stability were prepared with zirconium silicate(ZrSi).The composite material has excellent optical properties and high stability.We further explored the mechanism of high luminescence stability of ZrSi perovskite quantum dot composite material,expands the preparation of ZrSi/CH3NH3PbX3 and ZrSi/CsPbX3 perovskite quantum dot composite material covering the full spectral range,and explored the advantages of perovskite quantum dot nanocomposites in the field of lighting.Finally,combining carboxymethyl cellulose(CMC)with ZrSi,we designed and prepared CMC-ZrSi-CH3NH3PbX3 aerogel composites with high flexibility and strong deformability.The successful expansion of PQDs into the field of luminescent aerogels demonstrates the application potential of highly stable PQDs in various fields.