Preparation Of NANO-ZrO₂/polysiloxane Composite Film And Application In LED Double-layer Encapsulation

By designing the composition structure of the organic silicone encapsulating material and the matching of the multi-layer refractive index and the optimization of the thickness,the light output efficiency and stability of the LED can be further improved.To this end,this work firstly provide a design basis for the experiment through simulations and calculations,then a light-curable silicone resin that combined with modified ZrO₂ are applied to the LED double-layer Encapsulation.The effect of the matching of refractive index between the encapsulating layers and the change of thickness on light extraction efficiency(LEE)is studied.This work provides theoretical and experimental basis for the optimization of LED light extraction efficiency.The main contents are as follows.Rayleigh scattering formula,Fresnel formula and Lambert-beer law are combined to calculate and simulate the light transmittance of LED single-layer encapsulation and double-layer encapsulation.The result shows that the light transmittance of the LED double-layer encapsulation is better than that of the single-layer encapsulation.The simulation shows that double-layer encapsulation reaches the highest light transmittance when the thickness of the nano-composite encapsulation layer is less than 10?m.The matrix refractive index was 1.55 and the additive amounts of nanoparticles are about 65wt%(regardless of particle agglomeration)under this condition.In the research,a new type of polysiloxane(MD-DPS)is synthesized by the condensation reaction of dihydroxydiphenylsilane(DPSD)and 3-(dimethoxymethylsilyl)propyl methacrylate(MPDMS).MD-DPS has a high refractive index(RI=1.54)and easy-to-process viscosity which with high phenyl groups.It can be synthesized in a simple method and cured by ultraviolet light.Zirconium dioxide(ZrO₂)nanoparticles with high crystallinity were synthesized by hydrothermal method.Then modified particles(MP-ZrO₂)are obtained by using 3-trimethoxysilyl-propyl-methacrylate(MPTMS).It is compounded with synthetic resin(content is 0-20 wt%)to obtain a composite system with different MP-ZrO₂ content.The refractive index from 1.54-1.61 has been obtained for MP-ZrO₂/resin composites by adding 0-20 wt%ZrO₂.the LEE value was increased by 2%-5%compared with the single-layer encapsulated LED When the MP-ZrO₂/resin composites are applied to the LED double-layer encapsulation.The LEE value of the double-layer encapsulated LED sample is 1%-8%higher than that of the single-layer encapsulated LED sample after 4hours of sulfur resistance test.The relationship between the thickness of the encapsulating layer and the LEE in the LED double-layer encapsulation is studied.As the thickness of the nanocomposite encapsulation layer increased,the LEE value first decreases and then increases.The LEE can reach the highest value when the nanocomposite encapsulation layer is thinner(0.15?m).