Preparation, Properties And LED Device Research Of Cs_α(Pb/Cu_β)X_γ(X=Cl,Br) Materials Based On Perovskite Structur

Perovskite light-emitting diodes have attracted much attention due to their high photoluminescence quantum efficiency,tunable light emission wavelength,and high color purity.In recent years,researchers have done a lot of work on improving the performance of perovskite light-emitting diode devices,with external quantum efficiencies exceeding20%,representing an important step towards commercial applications.At present,the stability of blue perovskite materials has greatly hindered the progress of its commercialization,which is a huge challenge faced by the entire perovskite light-emitting diode field.Among them,the photoluminescence of perovskite quantum dots is affected when heated,and even decomposes directly when the external temperature is too high.Thermal stress also leads to accelerated oxidation and hydrolysis,induces fluorescence quenching,and has larger surface defects and poorer stability.Therefore,perovskite crystal materials are important materials for the application of light-emitting diode materials.In order to solve these problems,this thesis uses the thermal injection method to synthesize blue-emitting lead-based CsPbBr_1.5Cl_1.5 quantum dots and copper-based Cs₃Cu₂Br₅ quantum dots,and investigate the effect of surface engineering on the stability of quantum dots through surface engineering treatment.In addition,by preparing Cs₃Cu₂Br₅ single crystals combined with commercial phosphors or perovskite powders,white light-emitting diodes with white light emission with good stability and high color rendering index were prepared.The research contents of this thesis mainly include the following:The lead-based CsPbBr_1.5Cl_1.5 perovskite quantum dots were prepared by hot injection method,the surface of the quantum dots was purified,and then the short-chain ligands and long-chain ligands were exchanged to improve the stability of the quantum dots and its luminous properties.The copper-based Cs₃Cu₂Br₅ perovskite quantum dots were subjected to the exact same surface modification treatment,and the photoluminescence intensity was significantly different from that of the lead-based perovskite quantum dots.The phenomenon of photoluminescence intensity decreased and the stability was not stable.increase,indicating that surface engineering in the traditional sense has no effect on copper-based Cs₃Cu₂Br₅ quantum dots.Finally,the application of blue light emitting Cu-based Cs₃Cu₂Br₅ single crystal to white light LED devices is mainly introduced,the basic properties such as the color rendering index of the device are characterized,and the stability of the LED device is explored.Since the prepared yellow-green Cs Cu₂Cl₃ perovskite powder and blue Cs₃Cu₂Br₅ perovskite powder have different photoluminescence intensities under the same excitation wavelength,the amount of powder is adjusted according to the ratio of fluorescence intensity.The color rendering index of the device shows an obvious upward trend,and the thermal stability of the device is very good.