| In recent years,semiconductor quantum dot(QD)materials have attracted widespread attention and research due to their favorable photoelectric properties,which make them have broad application prospects in display,lighting,and biomedicine fields.However,QDs are extremely sensitive to external environment,water,oxygen,light and heat in the air environment can reduce their performance,and finally limit their practical applications.This thesis focuses on solving the problems of dispersion and stability of QDs in practical applications.The single-core double-shell QD composite materials based on cadmium-based and perovskite QDs have been prepared.The prepared QD composite material effectively improved the dispersion and stability of QD,and its fluorescence characteristics have been maintained.The main research content and results of this thesis are as follows:1、Taking the traditional core-shell structure QDs as the research object,with silica microspheres as the core,a layer of core-shell structure QDs was adsorbed on the surface of the silica spheres as the inner shell layer,and then the QD-adsorbed silica spheres were coated by a silica shell as the second shell.Through the optimization of catalyst and reaction reagents,the single-core double-shell structure QD composite material was prepared.By comparing the effects of QDs with different shell thickness on the properties of composite materials,we found that a thicker shell thickness can effectively inhibit the capture of excitons inside the QDs by the surface defects of QDs during the silica coating process.So the excitons can effectively radiate and recombine,thereby improving the fluorescence retention rate of QDs.2 、 The alloyed single-core double-shell QD composites were obtained by replacing the core-shell QDs with alloy QDs.The optimal coating thickness was 12 ±5 nm when the reaction time reached 6 h after adjusting the coating time.Alloy structure QDs have less lattice mismatch and lattice stress,so that the defects on the surface of QDs cannot capture the excitons inside the QDs during the coating process.And the non-radiative recombination was inhibited,thus the QD composites with high fluorescence retention rate were obtained.3、The perovskite QDs were grown on the surface of silica microspheres by ligandassisted reprecipitation(LARP)method at room temperature,and then the perovskite QDs were coated with a layer of silica to obtain the perovskite single-core double-shell QD composites.Fluorescence lifetime analysis showed that the fluorescence lifetime of the perovskite single-core double-shell structure QD composite(99.77 ns)was significantly longer than that of the perovskite QDs grown on the surface of silica spheres(55.53 ns)and pure perovskite QDs(40.64 ns).The stability test showed that the stability of the composite material was significantly improved compared with that of pure perovskite QDs.4、The prepared single-core double-shell structure QD composite material was applied to the QD light guide plate(LGP).The color coordinate of the prepared QD LGP was(0.3031,0.2854),and the color temperature(CCT)was 6419 K,which was close to the standard of D65 light source.Its color gamut was 123.32% NTSC,an increase of nearly 50% compared to the LED backlight on the market.Through the stability test,the prepared QD LGP has obvious stability improvement,including photo-thermal stability and moisture stability.This shows that the single-core doubleshell structure QD composite material can effectively improve the stability of the QD LGP. |
