Effect of Boron Nitride Nano-Particle on the Efficiency of Light Extraction Efficiency for Light-Emitting Diodes
| Autor: | Chia-Yi Yang, 楊家宜 |
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| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 LED becomes the shining star of green lighting source mainly due to its small size, high luminous efficiency, and energy savings. To increase the LED light extraction efficiency is the key to improve this technology. When the refractive index of the crystal grains (n=2.5) is higher than the air (n=1) and a high light refractive index difference in the interface is created, the narrow critical angle is formed. The light will be totally reflected due to the narrow critical angle, therefore the light generated would be easily confined LED inside. The light extraction efficiency becomes lower. In this research, we uniformly dispersed the Boron Nitride Nano-Particle (BN) (n = 1.7), which features not absorbing visible light and high refractive index, in silicone and in phosphor silicone encapsulation respectively. At same time, we utilized the high refractive index nature of BN on encapsulation material and different package structures through four experiments to increase the LED light extraction efficiency. Experiment I, different proportions of BN doping concentration in silicone ; Experiment II, different proportions of BN doping concentration in phosphor silicone encapsulation. From experiments I and II, we found the best optimal ratio to dope BN on LED package; Experiment III, doping BN with the best optimal ratio in the silicone ; Experiment IV, doping BN with best optimal ratio in the phosphor silicone encapsulation. Experiment III and experiment IV along with three different package structures: including doped BN uniformly in the encapsulation material of the entire package; or only doped BN uniformly on the upper encapsulation material package, but the lower layer is not doped; or only doped BN uniformly on the lower encapsulation material package, but the upper layer is not doped. From these four experiments, we have discovered doped BN uniformly only on the lower encapsulation material package but not the upper layer can effectively form the optimal refractive structure and furthermore to enhance the light extraction efficiency. In confidence interval testing, not only there is no difference for the LED components between doped BN and not doped BN in silicone and phosphor silicone encapsulation when light the LED for 1000 hours continuously, but also the high heat dissipation characteristics of BN reduces internal heat accumulation. Therefore, life time of internal LED components is extended because of slower deterioration. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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