Design And Research Of Enhancing LED Performance Based On Patterned Substrate

Light emitting diodes are called fourth-generation light sources,which have the advantages of energy saving,safety,long life,low power consumption and high brightness,and are widely used in many fields such as lighting and transportation.Aiming at the optimization of the luminous efficiency of LEDs,the thesis mainly studies multilayer hyperbolic metamaterial structures of different shapes,using multilayer film transmission matrix theory and finite difference time domain method to systematically study the factors affecting the luminous efficiency of LEDs,by changing the metal film,the thickness of the dielectric film,the distance between light emitting diode and the HMMs,and the length of the multilayer HMMs respectively proposed optimized design schemes.The main research content of this thesis is as follows:1.Based on the theory of surface plasmon resonance technology,the most typical layered metal-dielectric structure is studied,and the reflection characteristics of the multilayer film are simulated with the FDTD simulation software based on the finite difference time domain method.The SPR phenomenon is stimulated,and it is discovered that metal-dielectric films of different periods excite different BPP modes,the relationship between the reflectivity of nano-metal-dielectric multilayer films of different periods and the change of incident wavelength is studied in depth,which provides a basis for the design of LEDs with patterned substrates.2.Propose a patterned metal-dielectric multilayer LED structure,improve the luminous efficiency of the LED by changing the structure of the multilayer HMMs and metal materials,optimize the thickness of each layer,analyze the optimal value of the purcell factor,and study its light field distributed.The results show that when the incident light is irradiated from450nm-700 nm,the luminous efficiency of the circular Ag/Si multilayer HMMs is the best.The optimal thicknesses of the metal film,dielectric film and Ga N barrier layer are 20 nm,3nm and10 nm,respectively.The purcell factor of the LED is the highest,reach 183,which greatly enhances the luminous efficiency.3.Combining the two most typical hyperbolic metamaterial structures,namely the layered metal-structure and the metal nanowire array structure,a patterned metal-dielectric multilayer film array LED structure is proposed,based on the previous patterned metal-dielectric multilayer The optimal parameters of the film's LEDs are analyzed and the effects of the array spacing,the irradiation position of light emitting diode and the irradiation angle on the luminous efficiency of the LED are analyzed.The results show that when the incident light is located in the middle of the multilayer HMMs and irradiated vertically,the purcell factor is the largest,and it is 183,indicating that the LED array structure is feasible.