Study On Photothermoelectric Theory And Package Design Of UVB-LED

As the fourth generation of solid light source,light-emitting diodes(LEDs)are widely used due to the advantages such as small size,low energy consumption,long lifetime and green environmental protection.However,the application of LEDs still faces great challenges,such as crowded chip current,low external quantum efficiency(EQE)and high junction temperature.With the shorter radiation wavelength of LEDs,this disadvantage is more obvious in the ultraviolet band.At present,the radiation power and the wall-plug efficiency(WPE)of ultraviolet LED(UV-LED)are low.In addition to improving the internal quantum efficiency(IQE)by improving the epitaph process,the studies on packaging technology have a significant impact on improving the radiation characteristics of UV-LED and the external quantum efficiency of devices.This paper mainly focuses on the photothermoelectric theory and packaging technology of UVB-LED,and UV-LED with different chip sizes is designed and prepared,and its photothermal and electrical properties are explored.The specific research results are as follows:1.Through the exploration of photothermoelectric theory and the application of finite element method,PCT-LED and EMC-LED devices with different frames are designed and prepared.The study results show that the luminous efficiency and heat dissipation performance of PCT-LED are better than that of EMC-LED,and the distribution results of coupling simulation are also consistent with the experimental values.However,after comparing the optical power before and after the aging experiment,it is found that EMC-LED has better antiageing performance and stronger reliability than PCT-LED.This study also provides a theoretical and experimental basis for the packaging studies of UVB-LED.2.AlGaN-based UVB-LED devices with different chip sizes have been designed and prepared.The research shows that the chip size has a great influence on the radiation efficiency and heat dissipation performance of LED.Although the UVB-LED with chip size of 40 mil has a lower emission power than the UVB-LED with a chip size of 20 mil,its thermal parameters such as junction temperature and thermal resistance are less affected by the current,and heat dissipation performance is better.The accuracy of the model prediction is verified.3.In view of the heat dissipation problem of high-power UVB-LED modules,this study proposes two methods to reduce the working temperature and improve the heat dissipation performance:(1)The direct current driving is replaced by the pulse driving.By controlling the pulse frequency and duty cycle,the working time of the LED device is reduced and the heat generation of the chip is reduced;(2)The power UVB-LED module is equipped with an external radiator and connected with a heat conduction pipe.The simulation data show that the heat dissipation performance can be greatly improved and the working temperature of the module can be reduced by adding external radiators and the number of heat conduction pipes.