Research On Quantum Dot White LED Packaging Technology With High Stable Luminescence Performance

As a new type of light conversion material,quantum dot has excellent luminescent properties such as adjustable wavelength and good monochrome which can combine or replace traditional phosphor materials to improve the light-emitting effect of white LED.However,due to the problems of poor thermal stability and poor resistance to water and oxygen,the quantum dot white LED are difficult to maintain stable luminescent properties.This thesis focuses on the stability improvement of quantum dot white LED encapsulated by red quantum dots and green phosphors.The experimental work is carried out from the following points:First,in the improvement of thermal curing in the quantum dot white LED packaging process.By comparing different curing methods,it is concluded that the combination of low temperature delay and easy curing of the silica matrix can significantly improve the stability of the quantum dot white LED in the curing stage.In this experiment,the quantum dot white LED prepared by using OE-6662A/B type silica gel combined with 85?,4h curing condition has a quantum dot luminescence peak intensity maintenance rate of about 90%.Second,in the aspect of the failure of quantum dot white LED.By comparing and analyzing the normal temperature air environment,85(85?)environment,double 85(85?85%RH)environment and drive current four factors on the failure effect of quantum dot white LED.It is concluded that when the driving current is 120mA,the order of four influencing factors is:driving current>850C high temperature>85%RH high humidity>>normal temperature air.Therefore,under no special requirement,using a small current to drive the quantum dot white LED as much as possible.At last,in the optimization and comparison of the package structure of the quantum dot white LED.In order to improve the moisture resistance,a fluoropolymer moisture-proof material is added on the existing quantum dot white LED package structure.The double 85 reliability experiment results show that the fluoropolymer moisture-proof material can protect the quantum dot white LED and the protection effect is more obvious with the increase of concentration.To explore the impact of different package structure on the stability of quantum dot white LED,the experiment of four package structure quantum dot white LED under low current lighting condition is carried out.It is concluded that the quantum dot white LED of the conventional package structure has a slightly better stability under normal temperature air environment.And in the double 85 environment,the quantum dot materials in the four package structure are all failed in a short time.In order to further improve the stability of the quantum dot white LED,the new type package structure of quantum dot material is nested in a double-layer glass is designed.The quantum dot white LED of new type package structure continuously lit for 1000 hours in the double 85 environment,the experiment results show that the red and green two-color quantum dot luminescence peaks existed and the intensity maintenance rates were about 74%,79%respectively,the stability was significantly improved.Figure 52,table 9,references 42.