Research On Optical Efficiency Improvement Of Planar Near-ultraviolet LED And Its Application

Ultraviolet light-emitting diodes(UVLEDs)have important application prospects in the fields of disinfection,sterilization,full-spectrum lighting,and backlight display.However,its low optical efficiency has severely limited the industrial development of UVLEDs.For UVLED,packaging technology is a key part of the development of the UVLED industry.Through optical simulation,this research firstly explores the impact of two typical packaging structure designs on the performance of planar near-ultraviolet LED(NUVLED).In order to improve the luminous efficiency of NUVLEDs,the efficient packaging structure based on nanoparticles is proposed to prepare high-efficiency planar NUVLED devices.Finally,NUVLEDs based on the proposed packaging structure are applied to quantum dot LEDs(QD-LEDs).(1)Planar NUVLED design based on optical simulationThrough model simulation,this chapter compares the performance of all-inorganic packaging and organic silicone packaging structure design for planar NUVLEDs.In the allinorganic packaging structure,the surface reflectance and inclination of the LED bracket have a great impact on the optical performance.In the organic silicone packaging structure,in addition to the surface reflectance and inclination of the LED bracket,the refractive index and scattering properties of the organic silicone is further optimized for package.After system optimization,the radiant flux of planar NUVLED devices using the organic silicone packaging structure is 3.4 times of that using an all-inorganic packaging structure,and the light extraction efficiency is improved by 33.9%.Therefore,from the perspective of optical energy utilization efficiency,the organic silicone packaging structure is much more suitable for planar NUVLED packaging.(2)Research on preparation of high-efficient planar NUVLED devicesThrough analyzing the six common nanoparticles,boron nitride(BN)nanoparticles are most suitable for NUVLED packaging technology.Based on the organic silicone package,a BN nanoparticle-doped packaging structure is proposed to reduce the total reflection loss of the organic silicone and air interface.The radiant flux of the NUVLED device is improved by 8.1% after optimizing the BN doping concentration.In order to solve the serious light absorption loss on the surface of the LED bracket,an efficient nanoparticle reflective coating packaging structure is proposed.After comparing six kinds of nanoparticles,experiments have confirmed that BN nanoparticles are still quite suitable for this reflective coating structure.Through optimizing the structure based on the BN nanoparticle reflective coating,the light output power of the NUVLED is increased by 46.2%.Finally,the planar NUVLED device with high light output efficiency is prepared.(3)Application research of planar NUVLEDQuantum dot LED(QD-LED)has great potential in the next generation display technology.The optical properties of QD-LED under different excitation wavelengths,especially under NUV and blue-light excitation,are compared and studied.It is found that the NUV excitation solution has an advantage in colorimetry.In order to eliminate the residual NUV excitation peaks in quantum dot LED applications,a strategy combining a BN nanoparticle reflective coating and a reflective filter is proposed.Using this combination strategy,the QD-LED not only substantially eliminates the residual NUV excitation peaks,but also improves the green light emission intensity by 82.0%,compared with the conventional method using highconcentration QDs.This strategy has important practical significance for QD-LED application.