Browsing by Author "Li, Xiuling"

Now showing 1 - 6 of 6

Efficient hybrid white light-emitting diodes by organic-inorganic materials at different CCT from 3000K to 9000K
(2015-04-06)
Chen, Kuo-Ju
;
Lai, Yi-Chun
;
Lin, Bin-Cheng
;
Lin, Chien-Chung
;
Chiu, Sheng-Huan
The hybrid white light-emitting didoes (LED) with polyfluoren (PFO) polymer and quantum dot (QD) was investigated using dispensing method at the different correlated color temperature (CCT) for cool and warm color temperature. This result indicates that the hybrid white LED device has the higher luminous efficiency than the convention one, which could be attributed to the increased utilization rate of the UV light. Furthermore, the CIE 1931 coordinate of high quality white hybrid LED with different CCT range from 3000K to 9000K is demonstrated. Consequently, the angular-dependent CCT and the thermal issue of the hybrid white LED device were also analyzed in this study. (C) 2015 Optical Society of America
Improvement of light quality by DBR structure in white LED
(2015-02-09)
Lin, Huang-Yu
;
Chen, Kuo-Ju
;
Wang, Sheng-Wen
;
Lin, Chien-Chung
;
Wang, Kuan-Yu
This study demonstrates the application of DBR structure into the remote phosphor structure to improve the angular correlated color temperature (CCT) deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structure yielded a higher luminous efficiency than a conventional structure. The CCT deviation can be improved from 1758K to 280K in a range of -70 to 70 degree and the luminous flux increases more than 10% due to the enhancement of the light extraction of the blue light. Moreover, the reflectance of the different DBR structures is analyzed with different angles to reveal the reasons of such improvements. As the result, this LED device with DBR structure shows the great potential to use as the next generation lighting source. (C) 2014 Optical Society of America
Large Area MoS2 van der Waals Epitaxy on III-Ns and the Epitaxial Formation of a n-MoS2/p-InGaN Diode
(2016-01-01)
Jung, Kyooho
;
Liu, Che-Yu
;
Kim, J. D.
;
Choi, Wonsik
;
Zhou, Weidong
Epitaxial growth of aligned MoS2 triangles on GaN substrates and their evolution into a continuous sheet of >centimeter size are demonstrated. An n-MoS2/p-InGaN diode with clear rectifying behavior is realized by direct van der Waals epitaxy. Epitaxial growth of aligned MoS2 triangles on GaN substrates and their evolution into a continuous sheet of >centimeter size are demonstrated. An n-MoS2/p-InGaN diode with clear rectifying behavior is realized by direct van der Waals epitaxy.
Large-area, uniform white light LED source on a flexible substrate
(2015-09-21)
Sher, Chin-Wei
;
Chen, Kuo-Ju
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Lin, Huang-Yu
This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications. (C) 2015 Optical Society of America
Pseudo-van der Waals Epitaxy of MoS2 on Patterned and Planar GaN Substrates
(2019-01-01)
Liu, Che-yu
;
Choi, Wonsik
;
Huang, Hsien-chih
;
Kim, Jeongdong
;
Jung, Kyooho
n-MoS2/p-GaN diodes monolithically formed by pseudo-van der Waals epitaxy show well-defined rectifying behavior. Growth on patterned GaN substrates yields monolayer and few-layer MoS2 formation on the planar surface and the pyramids, respectively. (c) 2019 The Author(s)
Wide-Range Correlated Color Temperature Light Generation From Resonant Cavity Hybrid Quantum Dot Light-Emitting Diodes
(2015-07-01)
Chen, Kuo-Ju
;
Lin, Chien-Chung
;
Han, Hau-Vei
;
Lee, Chia-Yu
;
Chien, Shih-Hsuan
This study presents extremely uniform colloidal quantum dot white light-emitting diodes (QD-WLEDs) that demonstrate a high color rendering index (CRI) and correlated color temperatures (CCTs) ranging from 2500 to 4500 K. Experimental results indicate that the structure of the distributed Bragg reflector (DBR) containing a stopband in the UV region enhances the intensity output of both monochromatic QD-LEDs and QD-WLEDs by reflecting the unconverted UV light back onto the package to excite the QDs further. Furthermore, the angular CCT uniformity of the QD-WLEDs also improved considerably because of the dependence of the DBR structure on the incident angle. The angular CCT deviation in the range of -70 degrees to 70 degrees decreased to 39 K and the CRI of the WLED is higher than 90. The high-CRI and uniform angular CCT QD-WLED containing the DBR demonstrates potential applicability as the lighting source of next-generation display devices and solid-state lighting.