Research On Quantum Dots Composite Materials Used In Pc-LEDs Packaging

Owing to its long service life,environmental protection and energy saving,green and high-efficiency,the LED(Light Emitting Diode)lighting technology has gradually become the mainstream of the lighting industry.Among them,phosphor-converted LED is the main way to achieve white light illumination.But,traditional phosphors have limited their development and application due to high cost and high pollution.Thus,the development of new fluorescent materials is a top priority.Among them,quantum dots have become the first choice for the majority of scholars due to their advantages such as adjustable size,wide excitation spectrum coverage,narrow emission spectrum,excellent fluorescence performance,and diverse preparation methods.In this paper,to synthesizing quantum dot materials that can replace partially or fully traditional phosphors,we design a novel quantum well composite structure of cadmium-containing quantum dots to achieve tunable size in a wide spectral range and improve the problem of insufficient red light composition in conventional pc-LEDs,and improve its color rendering.For this reason,we prepare CdSe/ZnS quantum dots by the solvothermal method based on the LSS three-phase system,which verified the rationality and feasibility of the scheme.At the same time,the structure and synthesis scheme of CdSe_xS_1-x/CdSe/ZnS quantum well quantum dots were further designed,and we discuss the influence of key experimental parameters on the experimental results.Finally,quantum dot composite material with a tunable size,good dispersion,and high stability were successfully prepared.Then we use it in the packaging of pc-LEDs.The specific work points are as follows:(1)Ethanol and oleic acid form the liquid L phase,sodium oleate forms the solid S phase,and the aqueous solution containing the reactant ions and ethanol form the solution S phase,which together form the LSS three-phase system.And under solvothermal conditions,a controllable synthesis with a temperature ranging from140�C to 200�C and a reaction time ranging from 2h-11h was achieved.(2)Synthesis and characterization of wavelength-tunable CdSe/ZnS core-shell quantum dots.The CdSe/ZnS core-shell quantum dots were successfully synthesized by the solvothermal method based on the LSS three-phase system,which verified the rationality of the experiment and obtained reproducible experimental results.Through the optimization of experimental parameters,the luminescence wavelength of quantum dots in the range of 540nm-600nm is adjustable.We characterize the physical properties of the synthesized quantum dot products through transmission electron microscopy and fluorescence spectrophotometer.(3)Synthesis and characterization of wavelength-tunable CdSe_xS_1-x/CdSe/ZnS quantum well quantum dots.We designed CdSe_xS_1-x/CdSe/ZnS quantum well quantum dots,and we prepared CdSe_xS_1-x/CdSe/ZnS quantum dots successfully using the solvothermal method based on the LSS three-phase system,and through composition control.We achieved the luminous wavelength in the range of 540nm-700nm inside is adjustable.Also,through the optimization of experimental parameters(including drug dosage,temperature,and time),the conclusion of the law that affects the experimental results is obtained.At the same time,the test and characterization obtained CdSe_0.1S_0.9/CdSe/ZnS quantum dots with a particle size of 11.26�5.91nm,a dominant wavelength of emitted light of 670nm,and a FWHM of 50nm.(4)Packaging and testing of pc-LEDs based on quantum dot composites.The white and red light emission were successfully realized by using the prepared quantum dots,which improved the deficiency of red light composition and enhanced the color rendering of the device.