Browsing by Author "Lin, Chien Chung"

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A novel randomly textured phosphor structure for highly efficient white light-emitting diodes
(2012-03-16)
Chen, Hsin Chu
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Chen, Kuo Ju
;
Wang, Chao Hsun
;
Lin, Chien Chung
;
Yeh, Chia Chi
We have successfully demonstrated the enhanced luminous flux and lumen efficiency in white light-emitting diodes by the randomly textured phosphor structure. The textured phosphor structure was fabricated by a simple imprinting technique, which does not need an expensive dry-etching machine or a complex patterned definition. The textured phosphor structure increases luminous flux by 5.4% and 2.5% at a driving current of 120 mA, compared with the flat phosphor and half-spherical lens structures, respectively. The increment was due to the scattering of textured surface and also the phosphor particles, leading to the enhancement of utilization efficiency of blue light. Furthermore, the textured phosphor structure has a larger view angle at the full width at half maximum (87A degrees) than the reference LEDs.
Enhanced Luminous Efficiency of WLEDs Using a Dual-Layer Structure of the Remote Phosphor Package
(2013-06-15)
Chen, Kuo-Ju
;
Chen, Hsin-Chu
;
Shih, Min-Hsiung
;
Wang, Chao-Hsun
;
Tsai, Hsin-Han
This study demonstrates how the insertion of a thin silicone layer into a dual-layer remote phosphor structure enhances light extraction in white light-emitting diodes (WLEDs). In the experiment, a dual-layer phosphor structure yielded a higher intensity of blue and yellow components than a conventional structure. Moreover, the lumen flux was 5% higher than a conventional remote phosphor package at the same correlated color temperature (CCT). Using a TFCalc32 simulation, the electric field intensity was calculated for different thicknesses of the dual-layer remote phosphor structures, and the enhanced use of blue rays was verified. Additionally, the dual-layer structure reduces chromaticity deviations as the driving current increases.
Enhanced performance of nitride-based ultraviolet vertical-injection light-emitting diodes by non-insulation current blocking layer and textured surface
(2014-12-29)
Chiang, Yen Chih
;
Lin, Bing Cheng
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Chen, Kuo Ju
;
Lin, Chien Chung
;
Lee, Po Tsung
For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated. The optical and electrical characteristics were investigated in this n-CBL UV-VLED. Furthermore, the efficiency of optimized structure was improved by 5 similar to 6 times compared to our reference.
Novel thin-GaN LED structure adopted micro abraded surface to compare with conventional vertical LEDs in ultraviolet light
(2015-04-15)
Chiang, Yen Chih
;
Lin, Chien Chung
;
Kuo, Hao Chung
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光電系統研究所
;
照明與能源光電研究所
In this study, novel thin-GaN-based ultraviolet light-emitting diodes (NTG-LEDs) were fabricated using wafer bonding, laser lift-off, dry etching, textured surface, and interconnection techniques. Placing PN electrodes on the same side minimized the absorption caused by electrodes in conventional vertical injection light-emitting diodes (V-LEDs) and the current spreading was improved. The light output power (700 mA) of the NTG-LEDs was enhanced by 18.3% compared with that of the V-LEDs, and the external quantum efficiency (EQE) of the NTG-LEDs was also relatively enhanced by 20.0% compared with that of a reference device. When the current operations were 1,500 mA, the enhancements of the light output power and EQE were 27.4% and 27.2%, respectively. Additionally, the efficiency droop was improved by more than 15% at the same current level.