Student Paper Award Announced!!

Session Index

Solid State Lighting

Oral Session 1 - Solid State Lighting
Thursday, Dec. 4, 2014  13:30-15:00
Chair: Ching-Cherng Sun,Chia-Feng Lin
Room: B22
13:30 - 14:00 Paper No.  2014-Thu-S0801-I001
Invited Speaker:
Sune Svanberg
Laser remote sensing of the atmosphere: Atoms, molecules, particles, insects and birds
Sune Svanberg,Sune Svanberg,

An overview of optical probing of the atmosphere will be given, where mostly active remotesensing techniques of the laser-radar type will be covered, but also some passive techniques employing ambient radiation. As the title suggests, objects of quite varying sizes can be studied. Mercury is the only pollutant in atomic form in the atmosphere, while other pollutants are either molecular or in particle form. Light detection and ranging (Lidar)techniques allow three-dimensional mapping of such constituents. More recently, flying insects and birds have been studied in projects of considerable ecological interest. Mostly, elastic backscattering and fluorescence techniques are employed. Some references to some recent activities by the author are given.

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14:00 - 14:15 Paper No.  2014-Thu-S0801-O003
Yu-Lin Tsai Award Candidate External quantum efficiency enhancement of GaN-based LEDs with multi-layers of nano-air-voids
Yu-Lin Tsai,Che-Yu Liu,Chirenjeevi Krishnan,Tsung-Sheng Kao,Da-Wei Lin,Martin D. B. Charlton,Chien-Chung Lin,Peichen Yu,Hao-Chung Kuo,

A novel mask-free fabrication process for homogeneously embedding multi-layers of nano-air-voids in GaN has been successfully developed. These nano-air-voids also show its great advantages in enhancement of the EQE up to 16.2% in GaN-based LEDs.

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14:15 - 14:30 Paper No.  2014-Thu-S0801-O008
An-Jye Tzou Award Candidate The Efficiency Droop Behavior Improvement through Barrier Thickness Modification for GaN-on-Silicon Light Emitting Diodes
An-Jye Tzou,Bing-Cheng Lin,Zen-Yu Li,Chun-Yen Chang,Hao-Chung Kuo,

The crack-free GaN-on-silicon light emitting diodes (LED) with improved droop behavior was achieved. Through the thinner design of quantum barriers (QBs), the LED with 8 nm-thick QBs shows a good peak EQE, and a 13.85% droop behavior was obtained.

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14:30 - 14:45 Paper No.  2014-Thu-S0801-O011
Tzu-Pei Chen Award Candidate Characteristics of green InGaN/GaN multiple quantum well grown on top-down nonpolar GaN nanorods arrays
Tzu-Pei Chen,Hao-Chung Kuo,Wei-Chi Hsu,Da-Wei Lin,Jhih-Kai Huang,Tsung-Sheng Kao,

Tip-free core-shell nonpolar green InGaN/GaN light-emitting diodes (LEDs) have been successfully designed and characterized. Electroluminescence measurement showed a slight blue-shift as the injected power increases. Through this 3-dimention current spreading layer, a high efficient 3D green LED device could be achieved.

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14:45 - 15:00 Paper No.  2014-Thu-S0801-O016
Yang Ta Shih Award Candidate Advantage of Asymmetric Triangular Multiple Quantum Wells in GaN-based Light Emitting Diodes
YangTa Shih,TienChang Lu,

We report on high-efficiency GaN-based LEDs using different asymmetric triangular multiple quantum well. The experiment results show that the gallium-face oriented inclination asymmetric triangular MQW (GOAT-MQW) and nitrogen-face oriented inclination asymmetric triangular MQW (NOAT-MQW) not only have better optical performance but reduce efficiency droop in compared to symmetric square MQW (SS-MQW). The simulation results were in good agreement with the experimental results.

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Solid State Lighting

Poster Session 1
Thursday, Dec. 4, 2014  15:00-16:20
Paper No.  2014-Thu-P0801-P002
Liu Keng-Chen Award Candidate Characteristics research of different size embedded electrodes GaN LEDs
Liu Keng-Chen,

Small size Embedded electrodes GaN LED (S-LED) is developed to improve light extraction efficiency and in this research. The heat dissipation performance could be improved by small size effect. Improved heat dissipation performance caused better photoelectron transfer efficiency and lower power consumption.

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Paper No.  2014-Thu-P0801-P005
Award Candidate Effect of Current Blocking Layer on the Light Output in GaN-Based Ultraviolet Light-Emitting Diodes

A SiO2/TiO2 distributed Bragg reflector (DBR) and a reflective electrode (R-pad) as a hybrid reflective current blocking layer (CBL) was prepared on the 370 nm ultraviolet light-emitting diodes (UV-LEDs). It was found that the output power was 145.6 mW for the UV-LED with a 5-pair DBR+R-pad CBL at 350 mA.

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Paper No.  2014-Thu-P0801-P008
Jiong-Fu Huang Award Candidate Plasmonic Effects of Gold Nanoparticle-Decorated Graphene Oxide Nanocomposites on the Performance of Polymer Light-Emitting Devices
Chun-Hao Lin,Jiong-Fu Huang,Fang-Chung Chen,

In this work, we blended gold nanoparticle-decorated graphene oxides (AuNPs-PEG-GO) into the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) layer and emission layers of green phosphorescent polymer light-emitting diodes. The device efficiencies have improved substantially. We contributed the device enhancement to the effects of the localized surface plasmon resonance induced by Au nanoparticles of the AuNPs-GO nanocomposites.

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Paper No.  2014-Thu-P0801-P011
Jie-Ru Li Award Candidate High Color Rendering Index Quantum Dots White Light-Emitting Diode with Capped Distributed Bragg Reflector Structure
Jie-Ru Li,Hao-Chung Kuo,Kuo-Ju Chen,Shih-Hsuan Chien,Chien-Chung Lin,

Excellent uniformity colloidal quantum dot white LED with high CRI were demonstrated with different CCT from 2500 K to 6500K. The experimental results showed that the DBR structure could enhance the intensity output by reflecting unconverted UV light.

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Paper No.  2014-Thu-P0801-P014
Che-Yu Liu Award Candidate Highly Light Extraction Ability GaN-based Light Emitting Diodes by Using Hybrid Micro-holes and Nano-rods structure
Che-Yu Liu,Hao-Chung Kuo,

High light extraction GaN-based light-emitting diodes (LEDs) with a hybrid structure of straight nanorods located in an array of microholes have been successfully demonstrated. The light output power of the hybrid nanorods LED is 22.04 mW at the driving current standard of 25.4 A/cm2, an enhancement of 38.7 % to the conventional GaN-based LEDs.

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Paper No.  2014-Thu-P0801-P017
WEI-CHU SUN Fabrication of micro-trapezoidal arrays for efficacy improvement of organic light-emitting diodes

This study is focused on the fabrication of the micro-trapezoidal arrays and their application on efficacy enhancement of organic light emitting diodes (OLEDs). The micro- trapezoidal arrays were made by the combination of photolithography, polydimethylsiloxane molding and UV forming techniques. The efficacy of the OLED increases with decreasing the gap distance of attached micro-trapezoidal array. In fact, the micro-trapezoidal array can improve efficacy of the OLED up to 50%.

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Paper No.  2014-Thu-P0801-P020
Yu-Chi Fang Color Mismatching between Different Sizes of CCT tunable LEDs
Yu-Chi Fang,Hung-Shing Chen,Jung-Chieh Su,

This paper reported color property and electro-optical transfer property of three primary emission colors between small-size LED and large-size LED. The mismatching of color gamut and tone response curve between them cause chromaticity inconsistency of different size CCT tunable LEDs.

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Paper No.  2014-Thu-P0801-P023
Yu-Chen Lin Influence of Buffer Growth Condition on the Reliability of InGaN LED
Yu-Chen Lin,Man-Fang Huang,Chia-Hung Sun,Hsu-Han Yang,Hong-Jie Zhaung,Ya-Hsuan Shih,Ming-Cheng Lo,Tzung-Te Chen,

This paper reports the dependence of buffer growth condition on reliability of InGaN LED. Experimental results showed that LED grown on a low-temperature and low-growth-rate buffer layer has less defect density, smaller power degradation and voltage increase, compared with LED with a buffer grown using high temperature and growth rate.

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Paper No.  2014-Thu-P0801-P026
Yu-Wen Chern Simulation of Quantum Well Optimization in Light-Emitting Transistors
Yu-Wen Chern,Chao-Hsin Wu,

The DC electrical and optical characteristics of light-emitting transistors are obtained by using Silvaco TCAD. Based on the optimization of the quantum well location in the simulated light-emitting transistors, the device where quantum well near the collector can get both the high current gain and high optical output.

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Paper No.  2014-Thu-P0801-P029
Yi-Yin Kuo Novel Glass-Based Phosphor-Converted for Laser Illumination Source
Yi-Yin Kuo,Li-Yin Chen,Jin-Kai Chang,Wei-Chih Cheng,Yi-Chung Huang,Wood-Hi Cheng,

In this study, we demonstrated a glass phosphor combining with a blue laser diodes as a solid-state lighting source. The glass phosphor with 30wt% phosphor concentration has high reflection-fluorescence luminous flux up to 165 lm.

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Paper No.  2014-Thu-P0801-P032
Yung-Fu Chang The Performance of InGaN/GaN LEDs with Al and Ga co-doped ZnO by ALD as Transparent Conductive Layer
Yung-Fu Chang,Chien-Lan Liao,Jia-Zhe Liu,Wei-Hao Lee,Chong-Lung Ho,Meng-Chyi Wu,

In this paper, we present the ZnO co-doped by Al and Ga by ALD. The Al and Ga co-doped ZnO (AGZO) shows low resistivity and high transparency. As compared with the InGaN LED with GZO, an increment of light output power by 10.1% for an AGZO-coated InGaN/GaN MQW LED.

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Paper No.  2014-Thu-P0801-P035
Chun-Ta Yu Characterization of thick InGaN wells with alternative grown InN/GaN on green light-emitting diodes
Chun-Ta Yu,Wei-Chih Lai,Cheng-Hsiung Yen,Shoou-Jinn Chang,

The authors report the use of InN/GaN alternative structure to replace the thick InGaN well layers in the InGaN/GaN multiquantum well (MQW) and the fabrication of GaN-based green light-emitting diodes (LEDs). Using this method, it was found that we could achieve InGaN “well layers” with high crystal quality due to the enhanced migration of adatoms during the growth. It was also found that indium composition in the InGaN “well layers” and the thickness of the InGaN “well layers” both depend strongly on the growth time of InN and GaN. It was also found that we could achieve stronger electroluminescence (EL) intensities with narrower full-width-half-maxima (FWHMs) from the LEDs with InN/GaN alternative growth InGaN “well layers”.

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Paper No.  2014-Thu-P0801-P038
Lin Huang Yu Improvement the color uniformity of white LED by Distributed Bragg reflector structure
LinHuang Yu,Chen Kuo-Ju,Wang Sheng-Wen,Lin Chien-Chung,Wang Kuan-Yu,Li Jie-Ru,Chen Huang-Ming,Kuo Hao-chung,

This study demonstrates the application of DBR structure into the remote phosphor structure to improve the angular CCT deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structure yielded nice color uniformity that the CCT deviation can be improved from 1758K to 280K.

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Paper No.  2014-Thu-P0801-P041
Hao-hsuan Huang Cooling apparatus using solid-liquid phase-change material
Hao-hsuan Huang,

A cooling apparatus using solid-liquid phase-change material (PCM) is proposed to achieve effective thermal management of high power LEDs. The high heat capacity and high latent heat of PCM effectively slow down the temperature rise to ensure LEDs can be operated at a lower temperature for a finite operation time.

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Paper No.  2014-Thu-P0801-P044
Chen-Yu Chang Application of Surface Guide Mode Resonance Enhancement on Nonpolar GaN Light-emitting Diodes
Chen-Yu Chang,Jian Jang Huang,

With the specific light direction and affectless of quantum-confines Stark effect (QCSE), non-polar GaN light-emitting diodes (LEDs) has been widely investigated and developed with its specialized optical properties. In our research, we demonstrate the a-plane GaN LED with two dimensional Photonic Crystal (PhC) surface guide mode structure.

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Paper No.  2014-Thu-P0801-P047
Ming-Yuan Huang Light extraction enhancement in the green organic light emitting diode by using photonic quasi-crystals
Ming-Yuan Huang,

This study shows the enhanced light extraction efficiency from organic light emitting diodes (OLEDs) by fabricating the device on the photonic quasi-crystal (PQC) substrate. The experimental results demonstrate that the green OLED with the PQC substrate increases the external quantum efficiency (EQE) by 20.0% compared to the standard.

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Paper No.  2014-Thu-P0801-P050
Chen-Kuo Wu The Effects of Random Indium Fluctuations on InGaN Quantum Well LEDs with Different Growth Orientations
Chen-Kuo Wu,Yuh-Renn Wu,

Abstract—In this paper, we studied the turn-on and IQE behaviors of c-plane, semipolar(20-21), and non-polar LEDs. The percolation transport of the carriers induced by the random alloy potential fluctuation has been considered with a full 3D transport model and compared with the different growth orientations.

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Paper No.  2014-Thu-P0801-P053
Min-Cheng Haung Achromatic projection low beam Design
Min-Cheng Haung,Chi-Hung Lee,Chia-Hsian Yang,Shih-Hsin Ma,

In this study, an achromatic projection-type low-beam headlight had been proposed. The headlight was composed by a WLLED, an ellipsoidal reflector, a stop, and an achromatic doublet. The light pattern which was 25m away had been simulated and tested by ECE R112 regulation. Moreover, the dispersion extent of the headlight light pattern which is 25m away was measured by a spectrometer. Finally, according to the experimental results of dispersion extent, the dispersion extent can be improved to narrower 1cm.

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Paper No.  2014-Thu-P0801-P056
Chang Mei-Ying The process condition effects on spirobifluorene derivative and its application in white OLED
Chen Hsin-Yu,Chang Mei-Ying,

This research controls emitting spectrum with white light emitter in single emitter by multi-methods for film fabrication using blue light emitting material TPSBF. We study mechanism of spectrum containing multiple emissions wavelength by thicknesses and deposition rates. As results, efficient and brightness white organic light emitting devices were obtained.

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Paper No.  2014-Thu-P0801-P057
Lin Wei Ming Organic Light-Emitting Diodes with Aluminum Zinc Oxide Embedded Anodes
LinWei Ming,HsuChing Ming,LinBo Ting,ZengYing Xun,WuWen Tuan,

The current efficiency of OLEDs was enhanced up to 64% using AZO embedded ITO anodes, attributed to the improved light extraction by additionally created optical reflection and scattering at the AZO wall. The current efficiency was limited by the increase in haze or electrical resistance of AZO embedded ITO film.

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Paper No.  2014-Thu-P0801-P060
You-Chen Chu Investigation of strain relaxation induced wavelength shift in InGaN/GaN nano-ring light-emitted diodes
You-Chen Chu,Hao-Chung Kuo,

The strain relaxation in InGaN/GaN MQW LEDs by using the nano-ring structure was demonstrated through the nanosphere lithography. When comparing with the sample without nano-ring structure, a blue-shift of emission wavelength of 18nm can be achieved by using a nano-ring structure with wall width of 60nm.

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Paper No.  2014-Thu-P0801-P061
Chien-Rong Yu Advantages of Tapered AlGaN Electron Blocking Layer in InGaN-based Light-Emitting Diodes
Chien-Rong Yu,Bing-Cheng Lin,An-Jye Tzou,Yuh-Jen Chen,Chun-Yen Chang,Hao-Chung Kuo,

A tapered AlGaN electron blocking layer (EBL) is experimentally and numerically analyzed in blue light-emitting diodes (LEDs). The simulation results demonstrate that the hole injection and further electron confinement could be effectively enhanced with tapered structure. Consequently, the experimental result exhibits a reduction of efficiency droop behavior in tapered-EBL LEDs.

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Paper No.  2014-Thu-P0801-P064
Wen-Hao Liu Synthesis and Luminescence Characteristics of Green SrZn2(PO4)2:Mn2+ Phosphors
Wen-Hao Liu,

Mn2+ doped SrZn2(PO4)2 phosphor was prepared under reducing atmosphere by solid state reaction method. Luminescence measurement showed that the SrZn2(PO4)2:Mn was a promising green phosphor for photoelectronic devices. The influence of Mn doping concentration on the luminescence properties of phosphor were investigated and discussed.

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Paper No.  2014-Thu-P0801-P065
Jian-Ping Wu High Color Rendering Index and Chromatic-Stable Tandem White OLED
Xuan-Fu Chen,Jian-Ping Wu,Su-Hua Yang,

A chromatic-stable tandem white organic light emitting diode with a high color rendering index (CRI) was designed. The concentration of DCJTB emitter was optimized. A maximum CRI of 84 at 13 V and the highest chromatic stability were achieved when 0.25% DCJTB was doped into the emission layer.

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Paper No.  2014-Thu-P0801-P066
An-Yung Shiu The Optical Characteristics of Improved SPE Package Structure for Phosphor-converted LEDs
An-Yung Shiu,Shang-Ping Ying,

This study proposes an improved SPE package structure that utilizes a reflection plate on the remote phosphor layer. The thin remote phosphor lay below the reflection would reduce the re-emitting light absorbed by other phosphor in the phosphor layer, and then increase the intensities between 500-550nm.

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Solid State Lighting

Oral Session 2 - Solid State Lighting
Thursday, Dec. 4, 2014  15:30-17:30
Room: B22
Notes: N/A
15:30 - 15:45 Paper No.  2014-Thu-S0802-O002
Yen-Hsiang Hsu Award Candidate Nanoscale epitaxial lateral overgrowth of GaN-based light-emitting diodes on an AlN nanorod-array template
Yen-Hsiang Hsu,Chen-Hung Tsai,Yu-Feng Yin,Hsiang-Wei Li,Wei-Chih Lai,JianJang Huang,

We propose an AlN nanorod template grown on sapphire substrate using vapor-liquid-solid (VLS) method. The corresponding material quality, including voids near nanorods, Raman spectra and transmission electron microscopy (TEM) images, indicates significant improvement. Internal quantum efficiency (IQE) of the device with the proposed AlN nanorod template increases 12.2% as compared with the reference sample without AlN rod.

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15:45 - 16:00 Paper No.  2014-Thu-S0802-O003
Cheng-Han Wu Award Candidate Voltage modulation of a tunnel junction light-emitting transistor via photon-assisted tunneling
Cheng-Han Wu,Chao-Hsin Wu,

We demonstrate the voltage modulation of a tunnel junction light-emitting transistor (TJLET) via Franz-Keldysh photon-assisted tunneling. The base-collector tunnel junction can be effectively controlled by the change of voltage. A resonant optical modulation bandwidth up to 7.6 GHz is obtained when the TJLET is operated in negative differential resistance region.

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16:00 - 16:15 Paper No.  2014-Thu-S0802-O011
Ming-Shiou Tsai Award Candidate Spatial-color Model for Light Distribution of Phosphor-converted White LEDs
Ming-Shiou Tsai,Yu-Yu Chang,Yu-Huan Wang,Ching-Yi Chen,Yi-Chien Lo,Chien-Hung Hsu,Ching-Cherng Sun,

A modeling algorithm is proposed for pcW-LEDs, and it can be applied to accurately simulate color appearances, potentially enabling optical designers to remove yellowish/bluish spots in LED lighting. The developed optical model can predict the behavior of light sources with adding TIR lens. Accordingly, the color uniformity is improved with the appropriate optical design.

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16:15 - 16:30 Paper No.  2014-Thu-S0802-O012
Shih-Yu Tu Award Candidate Speckle suppressed blue laser light in a micro-vibrated phosphor paper
Shih-Yu Tu,Hoang Yan Lin,Tsung-Xian Lee,

In this paper, we have demonstrated an efficient speckle suppressed technique for a blue laser light in a micro-vibrated phosphor paper. The speckle contrast could be reduced from 51% to 7.4%. A mixing speckle contrast is defined for LD pumped phosphor material. The almost speckle-free result is achieved.

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16:30 - 16:45 Paper No.  2014-Thu-S0802-O021
Chung-cheng Hsu 3D Finite Element Strain Analysis of InGaN Quantum Well with Indium Fluctuations
Chung-cheng Hsu,Yuh-Renn Wu,

In this paper, we developed a 3-D finite element method for the strain calculation. With this program, it is able to calculate the strain distribution inside a quantum well (QW). We analyzed the strain distribution of nanowire based QW with indium fluctuation and compare the difference with the ideal normal nanowire QW. With this method, it is possible for us to accurately estimate the piezoelectric polarization inside the quantum well.

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16:45 - 17:00 Paper No.  2014-Thu-S0802-O022
Yi-Ju Wu General Method for Freeform Lens Design in White Light-Emitting Diodes
Yi-Ju Wu,Li-Yin Chen,

In this study, we proposed a general method for freeform lens design in white light-emitting diodes. The design method was then verified by Monte Carlo ray tracing system. The simulation result shows a huge improvement on illuminance uniformity, from 35.4% to 94.3%.

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17:00 - 17:15 Paper No.  2014-Thu-S0802-O025
Jhih-You Cai A Novel Lighting Design of Optical-adjustable Illumination with Surface-structured Diffuser by Index-matching Liquid
Jhih-You Cai,Xuan-Hao Lee,Chi-Shou Wu,Kuan-Hung Lee,Tsung-Hsun Yang,Ching-Cherng Sun,

In this research, a novel lighting design for a different requirement target area is proposed. With the index-matching liquid, the micro lens array of surface structure diffuser is compensated through a certain level of index matching so that the illumination pattern is adjustable.

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Solid State Lighting

Poster Session 2
Thursday, Dec. 4, 2014  16:40-17:50
Paper No.  2014-Thu-P0802-P001
Rong-Ci Hong Steady State Analysis of the Thermal Resistance for Multi-chip LED
Rong-Ci Hong,Shang-Ping Ying,Huan-Yu Chien,

Abstract—This study investigated the thermal resistance measurement proposed by NIST to access the thermal resistance of multi-chip LEDs and the relation between the thermal resistances of single chip and the chip in the multi-chip LEDs. It is found that the thermal resistance of the chip in four-chip 7070 LED with one chip power on is lower than the measured thermal resistance of the four-chip 7070 with all chips power on. The low temperature contribution of the chips nearby the chip measured for the thermal resistance is resiponsible fot the low thermal resistance for the four-chip 7070 LED.

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Paper No.  2014-Thu-P0802-P004
Cheng-chin Chen Greatly Improved Efficiency Droop for InGaN-Based Green Light Emitting Diodes by Quaternary Content Superlattice Electron Blocking Layer
Cheng-chin Chen,Bing-Cheng Lin,An-Jye Tzou,Chun-Yen Chang,Hao-Chung Kuo,

We presented a low efficiency droop behavior green light emitting diodes (LEDs) with a quaternary content InAlGaN/GaN superlattice electron blocking layer (SL-EBL). The light output power shows a 57% enhancement and only 30% efficiency droop, which is attributed to a smooth band bending with a uniform carrier distribution.

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Paper No.  2014-Thu-P0802-P005
huan-Yu Chien The Optical characteristics of PC-LEDs with Different Phosphor Concentrations and Leadframe Reflectivity
huan-Yu Chien,Shang-Ping Ying,Rong-Ci Hong,

This study proposes the effects of phosphor concentration and leadframe reflectivity on the pc-LEDs manufactured by dispensing method. The simulated results show the luminous flux increases as the phosphor concentration increasin It is also found that the CCT of the pc- LEDs decreases as the phosphor concentration increasing.

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Paper No.  2014-Thu-P0802-P008
Jian-Yu Shen Spectral of phosphor-conversion light-emitting diodes for ultimate color rendering
Jian-Yu Shen,Shang-Ping Ying,Tzung-Te Chen,

We proposed the relation between the chromaticity of two phosphors pc-LEDs and shingle phosphor white pc-LEDs in this study. The blue chip, green and red phosphors are used to fabricate pc-LEDs. It is found that the chromatic coordinate of the LEDs with two phosphor should relate to the LEDs with single phosphor.

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Paper No.  2014-Thu-P0802-P009
Xinhui Chen Numerical Study of current spreading and light extraction in deep UV light emitting diode
Xinhui Chen,Yuh-Renn Wu,

The current crowding effect in AlGaN 275 nm deep UVLEDs has been investigated using 2D drift diffusion solver and Monte Carlo ray-tracing method. Optimized condition for both lateral and vertical structure is presented here by changing the spacing between 2 fingers. Graphene as contact layer also has been discussed in this paper.

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Paper No.  2014-Thu-P0802-P010
Huan-Yu Chien The Optical characteristics of PC-LEDs with Different Phosphor Concentrations and Leadframe Reflectivity
Huan-Yu Chien,Shang-Ping Ying,Rong-Ci Hong,

This study proposes the effects of phosphor concentration and leadframe reflectivity on the pc-LEDs manufactured by dispensing method. The simulated results show the luminous flux increases as the phosphor concentration increasin It is also found that the CCT of the pc-LEDs decreases as the phosphor concentration increasing.

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Paper No.  2014-Thu-P0802-P011
I-Hsin Lu Modeling for Carrier Transportation in Organic Light-emitting Diode by Considering Effective Tail States
I-Hsin Lu,Yuh-Renn Wu,

We developed the 1D Poisson and drift-diffusion Solver by considering the effective tail states and field-dependent mobility to simulate the organic materials, such as NPB or TAZ. With the obtained tail state distribution and the field dependent mobility model, we applied this result in modeling organic light emitting diodes.

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Paper No.  2014-Thu-P0802-P012
Lin Huang-Yu Improvement the color uniformity of white LED by Distributed Bragg reflector structure
Lin Huang-Yu,Chen Kuo-Ju,Wang Sheng-Wen,Lin Chien-Chung,Wang Kuan-Yu,Li Jie-Ru,Chen Huang-Ming,Kuo Hao-chung,

This study demonstrates the application of DBR structure into the remote phosphor structure to improve the angular CCT deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structure yielded nice color uniformity that the CCT deviation can be improved from 1758K to 280K.

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Paper No.  2014-Thu-P0802-P013
Chih-Hao Li Electrode Pattern Design for GaN Vertical Light Emitting Diodes on Nano-patterned Si Substrates
Chih-Hao Li,

Optimized electrode patterns of vertical GaN-based light emitting diodes are designed on nanoscale patterned Si substrates. By introducing the device parameters reported from literatures, a uniform current spreading distribution is obtained from our designed electrodes.

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Paper No.  2014-Thu-P0802-P014
Hsin-Jen Chen Bipolar Host for an Efficient Blue Phosphorescence Organic Light-Emitting Diode
Tien-Lung Chiu,Hsin-Jen Chen,Yu-Hsuan Hsieh,Man-kit Leung,Chi-Feng Lin,Jiun-Haw Lee,

A new bipolar material, CbzOXD, was synthesized to be the host of emitting layer doped with FIrpic inside an efficient blue phosphorescence organic light-emitting diode. The device showed the maximum efficiency performance, e.g. current efficiency of 25.1 cd/A, power efficiency of 16.8 lm/W and external quantum efficiency of 12%.

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Paper No.  2014-Thu-P0802-P015
Chian-Yu Chen Failure Origins of AlGaN/GaN Light Emitting Diodes by Reverse-bias Water Vapor Stress
Hsiang Chen,Chian-Yu Chen,Yun-Yang He,Shang-Ren Lin,Kun-Min Hsieh,Min-Han Lin,Ba Syuan Siao,Huan-Yu Shen,Chin-Pang Chen,Li-Chen Chu,Yu-Cheng Chu,

Resolving failure origins of AlGaN/GaN light emitting diodes (LED) has received intensive study recently. In this research, reverse-bias emissions and deformation of the contact near the surface have been observed in stressed devices moisture conditions. We performed detailed studies on forward and reverse I-V, breakdown current profiles, and optical and material observations to gain insight to failure origins of AlGaN/GaN LEDs. Our studies indicate that the deformation of the contact may cause the device failure.

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Paper No.  2014-Thu-P0802-P016
Shun-Yuan Huang The Material of Encapsulation of light-emitting diodes characteristic for short wavelength in high temperature aging test
Shun-Yuan Huang,Yii-Der Wu,Jau-Sheng Wang,

The light-emission diode has a good development in shorter wavelength, the major encapsulates material has a problem for the optics. Therefore we develop a novel material to encapsulate the ultraviolet-light emission diode module. The material of Sol-Gel has higher transmittance for the ultraviolet band and higher thermal stability than silicone.

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Paper No.  2014-Thu-P0802-P017
Yifan Liu Simulation on Parameters with Tracepro Based on New Remote Phosphor LED Design
Liu Yifan, Liang Hengmao, Lv Weiwen, Liu Jun, Wu Yiping,

The article focuses on simulation of remote phosphor LED with Tracepro. After designing three different models, we corroborate the circular plate structure is the most efficient. Based on this, we investigated the influence of concentration and thickness of phosphor on intensity and color temperature; hence figuring out optimal parameter settings.

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Paper No.  2014-Thu-P0802-P018
Lin Huang-Yu Improvement the color uniformity of white LED by Distributed Bragg reflector structure
Lin Huang-Yu,Chen Kuo-Ju,Wang Sheng-Wen,Wang Kuan-Yu,Lin Chien-Chung,Li Jie-Ru,Chen Huang-Ming,Kuo Hao-chung,

This study demonstrates the application of DBR structure into the remote phosphor structure to improve the angular CCT deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structure yielded nice color uniformity that the CCT deviation can be improved from 1758K to 280K.

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Paper No.  2014-Thu-P0802-P019
Yu-Chi Wang High-Reliability of Warm-White LEDs Containing Composite Silica Photonic Crystals
Yu-Chi Wang,Chun-Feng Lai,

In this study, we demonstrated a reduced phosphor use technique that applied to white light-emitting diodes (WLEDs) containing composite silica colloidal photonic crystals (c-SCPhCs) for developing the warm-white LEDs (w-WLEDs). Thus, WLEDs containing c-SCPhCs conducted a reliability analysis test that applied a temperature/relative-humidity at 85 °C/85 with 120 mA for 2500 h, determining no visible degradation in optical performance. We implemented a novel, inexpensive technique to produce high luminous flux w-WLEDs for use as a residential light source.

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Paper No.  2014-Thu-P0802-P020
Jia-Yu Zeng Excellent Color-Rendering Index Candlelight LEDs Containing Composite Photonic Crystals
Jia-Yu Zeng,Chun-Feng Lai,

In this study, a technique that saved phosphor use was applied to warm white light-emitting diodes containing composite colloidal photonic crystals to develop the candlelight that exhibits a high luminous flux (52 lm) and an excellent color-rendering index (CRI; 94). A novel, inexpensive technology was implemented to produce high-CRI candlelight LEDs for use as a residential light source.

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Paper No.  2014-Thu-P0802-P021
Yi Ting He Internal quantum efficiency droop of GaN LED
Yi Ting He,Min Gong,Zhi Ren Qiu,Bao Ping Zhang,Zhe Chuan Feng,

Internal quantum efficiency droop of GaN LED

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Solid State Lighting

Oral Session 3 - Solid State Lighting
Friday, Dec. 5, 2014  08:00-09:30
Room: B22
08:00 - 08:15 Paper No.  2014-FRI-S0803-O001
Fu-Pang Chen Improvement in the light-output efficiency of high-power vertical LEDs using silicon dioxide current distribution layer
Fu-Pang Chen,

A novel current distribution layer (CDL) was employed to improve the current spreading of a vertical light-emitting diode. Based on a 55x55 mil2 power chip having optimized CDL thickness and width of 500Å and 50µm, the best of VF and LOP were 2.97 V and 671.8 mW, respectively.

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08:15 - 08:30 Paper No.  2014-FRI-S0803-O010
Zong-Yi Tu A Large-area flexible phosphor film for superior performance of white light-emitting Diodes
Zong-Yi Tu,Chin-Wei Sher,Kuo-Ju Chen,Bing-Cheng Lin,Hau-Vei Han,Min-Hsiung Shih,Chien-Chung Lin,Hao-Chung Kuo,Chien-Chung Fu,Sheng-Huan Chiu,

This study demonstrates a low cost and flexible phosphor film for both cool and warm white LEDs. The luminous efficiency was improved by 6.7% and 7%, compared to conventional white LEDs, respectively. Furthermore, the flexible LEDs were demonstrated and show the great potential in lighting or biomedical applications.

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08:30 - 08:45 Paper No.  2014-FRI-S0803-O011
Bo-Yu Wei Investigation of Quantum Dot Color Conversion in GaN-Based Minimized LEDs with Reflectors and ZnO Nanorod Arrays
Chao-Jung Cheng,Hsin-Yin Lee,Ching-Ting Lee,Ying-Chien Chu,Yen-Hsiang Fang,Chia-Hsin Chao,Ming-Hsien Wu,Bo-Yu Wei,

In this work, the distributed bragg reflector and the hybrid bragg reflector were respectively stacked at the top and the bottom of the minimized QDs-LEDs with the zinc-oxide nanorod. The resulting characteristics verified that the chromaticity coordinate was located at (0.59, 0.26) and the red illumination intensity increased 57.4 %.

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08:45 - 09:00 Paper No.  2014-FRI-S0803-O022
Wei-Ju Hsu InGaN light-emitting diodes with embedded air-gap disks through laser-drilling and electrochemical processes
Wei-Ju Hsu,

InGaN-based light-emitting diodes with an embedded air-gap disk structure were fabricated using a laser drilling process and an electrochemical (EC) wet etching process to enhance the light extraction efficiency. The air-disk structure was formed by a one-step epitaxial growth process and a selective wet etching process on a highly doped GaN:Si layer. The light output power of the treated LED structure was enhanced by 22% compared with a conventional LED at 20 mA.

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09:00 - 09:15 Paper No.  2014-FRI-S0803-O023
Yu-Feng Yin Optical Frequency Response of Light-emitting Diodes with Embedded Photonic Crystals
Yu-Feng Yin,Yen-Hsiang Hsu,Liang-Yu Su,Yuan-Fu Hsu,Li-Cheng Chang,Chao-Hsin Wu,JianJang Huang,

Here, sub-GHz modulation of GaN-based photonic crystal light-emitting diodes (PhCLEDs) were demonstrated. The higher operation speed is attributed to faster radiative carrier recombination of extracted guided modes from the PhC microcavity. The optical -3-dB bandwidth up to 240 MHz (an 1.5-fold increase as compared to conventional LEDs) is achieved.

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09:15 - 09:30 Paper No.  2014-FRI-S0803-O031
Bing-Cheng Lin Advantages of InGaN/GaN Light-Emitting Diodes with a Quaternary Superlattices EBL
Bing-Cheng Lin,Chien-Chung Lin,Po-Tsung Lee,Hao-Chung Kuo,

InGaN/GaN light-emitting diodes (LEDs) with AlInGaN/AlGaN quaternary superlattices (SLs) electron blocking layer (EBL) were grown by metal-organic chemical vapor deposition. The simulation results demonstrated the LED with a AlInGaN/AlGaN quaternary SLs EBL have superior hole injection efficiency and lower electron leakage over the LED with a conventional AlGaN EBL.

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Solid State Lighting

Oral Session 4 - Solid State Lighting
Friday, Dec. 5, 2014  09:30-11:00
Room: B22
09:30 - 10:00 Paper No.  2014-FRI-S0804-I002
Invited Speaker:
Franz-Peter Wenzl
Phosphor converted LEDs: The challenges from an optical and thermal point of view
Franz-Peter Wenzl,Franz-Peter Wenzl,

In this contribution a comprehensive discussion on the impact of the phosphor layer of phosphor converted LEDs on the amount of light output, white light quality and heat dissipation upon the color conversion process will be given and some general requirements for improved solid-state lighting sources will be deduced therefrom.

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10:00 - 10:15 Paper No.  2014-FRI-S0804-O003
Kuan-Yu Chen Zn-VI Semiconductor Phosphors for White Light-Emitting Diodes
Kuan-Yu Chen,Pin-Chun Shen,Hua-Yi Hsueh,Ching-Fuh Lin,

Nowadays, efficient down conversion for white light-emitting diodes (white LEDs) is mostly based on rare-earth element doped or cadmium contained materials, which lead to serious environmental detriment. Therefore, we propose a novel strategy embracing environmental benignity to achieve brightly light conversions based on Zn-VI semiconductor nanoparticles.

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10:15 - 10:30 Paper No.  2014-FRI-S0804-O006
Chun-Hsiang Liao Predicting Discomfort Glare caused by LED Lighting with Different CCT
Chun-Hsiang Liao,Tsung-Xian Lee,

This study was to investigate the discomfort glare caused by LEDs with different correlated color temperature (CCT). A psychophysical experiment was performed to evaluate visual comfort, and a new evaluation model was established by modifying unified glare rating (UGR). These data will be very useful in establishing a comfortable and efficient lighting for the future smart lighting systems.

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10:30 - 10:45 Paper No.  2014-FRI-S0804-O009
Yu-Yu Chang The Analysis of Phosphor-converted White LED with Various Packaging Structures in Packaging Efficiency
Yu-Yu Chang,Cheng-Chien Chen,Ching-Yi Chen,Tsung-Hsun Yang,Ching-Cherng Sun,

In this study, packaging efficiency for four different packaging structures is presented. Based on the developed phosphor model, the packaging loss in these structures can be predicted. The tendency of the corresponding experimental measurement can match the simulated results, and the highest packaging efficiency can reach 63% accordingly. This analysis can provide to optimize the packaging structure.

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10:45 - 11:00 Paper No.  2014-FRI-S0804-O012
Hwang Jung-Min Tunable color rendering index with RGBY metameric colours LEDs
Hwang Jung-Min,Wang Mei-Tan,Lin Chih-Wei,Hsu Ke-Fang,

In this study, color rendeing index (CRI) is demonstrated has a high degree of selectivity in chromaticity diagram with RGBY metameric colours LEDs. However, there is a trade-off between high CRI and high luminous efficacy in LEDs. In this paper, the RGBY metameric colours LEDs was applied to adjust the CRI with acceptable luminous efficacy are evaluated.

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Solid State Lighting

Poster Session 3
Friday, Dec. 5, 2014  11:00-12:10
Paper No.  2014-Fri-P0803-P001
Shu-Bin Chuang Enhancement in Output Power of Blue Nitride-based Light Emitting Diodes with an Electron Retarded Layer
Shu-Bin Chuang,Chun-Kai Wang,Y. Z. Chiou,C. H. Yen,W. C. Lai,S. J. Chang,

We proposed LEDs with a p-type AlGaN layer as the electron retarded layer (ERL) in front of electron injection layer. From our result, the light output powers at an injection current of 60 mA can enhancement of 9.76%. The rest electrical and optical characteristics of LEDs was also have improved.

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Paper No.  2014-Fri-P0803-P002
Chien-Shou Tang Lumen Maintenance of High Power LEDs
Chien-Shou Tang,Ting-Jou Ding,Hong-Yu Chou Hong-Yu Chou,Tsung-Hsun Yang,

By analyzing the measurement spectral data in detailed, the characteristics including the luminous efficiency, the light decay, the thermal resistance and so on can easily be studied. Thus, the lumen maintenance of high power white LEDs can be explored with a systematic comparison. It is found that the lumen maintenance almost linearly decrease as the driving electric current increases.

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Paper No.  2014-Fri-P0803-P003
Hsing-Yen Lin Spectral Analysis on Thermochromism
Hsing-Yen Lin,Tsung-Hsun Yang,Ching-Cherng Sun,

In this work, the spectral analysis has been applied on the thermochromic materials. A quantitative model is established by analyzing the emission spectra of the thermochromism materials. As a result, a novel temperature sensing method and procedure can be further developed based on thermochromism.

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Paper No.  2014-Fri-P0803-P004
Shih-Yung Huang Characteristics of GaN Decomposition in Atmospheric Pressures
Shih-Yung Huang, Wei-Kai Wang,Po-Rung Lin

Behavior of thermal decomposition of GaN epilayers in atmospheric pressures was studied. Thermal dissociation reaction of GaN epilayers depends on the annealing temperature. The GaN epilayers is complete dissociation and has a GaO2H reactant on surface of exposed patterned sapphire substrates. We demonstrated that the complete decomposition reaction can be expressed as below equation:GaN(S) + H2(V) + 1/2 O2(V) + 1/4 N2(V) = 1/2 Ga(V) + 1/2 GaO2H(S) + 1/2 N2(V) + 1/2 NH3(V).

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Paper No.  2014-Fri-P0803-P005
Ke-Fang Hsu Flexible Panel Lighting with High Illumination Uniformity Incorporating a Microlens Array Design on A Polymer.
Ke-Fang Hsu,Chih-Wei Lin,Jung-Min Hwang,

In this study, a micro-lens array on the polymer material is analyzed in flexible LED panel lighting design. According to the simulation result, the improvement of the v-cut structure is more uniform for the panel lighting surface. By the molding method, a prototype flexible LED panel lighting had been demonstrated with uniformity 0.77 at 5.5mm thick module.

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Paper No.  2014-Fri-P0803-P006
Mei-Wen Chen Energy Saving Designs in Corridor Areas with Batwing Light Distribution.
Ke-Fang Hsu,Chih-Wei Lin,Jung-Min Hwang,Li-Ling Lee,Mei-Wen Chen,

In this study, the LED luminaire with batwing beam shape using in corridor is analyzed. Comparing with the T-bar fluorescent luminaire or lambertian beam shape lighting design, the batwing lighting distribution design in corridor can save more fixture numbers under same illuminance condition. Therefore, the suitable lighting distribution design in the corridor for energy-saving is achieved.

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Paper No.  2014-Fri-P0803-P007
Yen-Hsun Lee Improved Water Vapor Absorption Efficiency Using Carbon Nanotubes of Network Morphology
Wen-Tuan Wu,Shih-Han Lin,Yen-Hsun Lee,Ching-Ming Hsu,

This work demonstrated that vertically-aligned MWNTs reveal higher moisture content than that of horizontally-distributed MWNTs. However, the network morphology in horizontally-distributed MWNTs seems to prevent the absorbed H2O molecules releasing back in the compartment and then acting with Ca, thus leading to a lower WVTR.

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Paper No.  2014-Fri-P0803-P008
Hong-Jie Zhaung Influence of Carrier Gas Used in P-GaN Growth on the Failure Mechanisms of InGaN LED
Hong-Jie Zhaung,Man-Fang Huang,Chia-Hung Sun,Hsu-Han Yang,Yu-Chen Lin,Ya-Hsuan Shih,Ming-Cheng Lo,Tzung-Te Chen,

This paper studied the influence of carrier gas used in p-GaN growth one failure mechanisms of InGaN LEDs. Experimental results showed that LED with a p-GaN layer grown under hydrogen mixed with nitrogen gas, could effectively reduce Mg-H bond formation and defects, which exhibited stable output power and operation voltage.

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Paper No.  2014-Fri-P0803-P009
Chien-Chih Hsu Organic Light-Emitting Diodes based on phosphorescent Blue-Emitting Layer
Jian-Yang Lin,Chien-Chih Hsu,

In this work, the phosphorescent material TCz1 has been used as the blue-emitting layer for the flexible organic light-emitting diodes (OLEDs). The emission performance of the flexible OLEDs has been characterized and discussed in this work.

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Paper No.  2014-Fri-P0803-P010
Chih-Wei Lin Phosphor Layer Design Optimization for LED Package by Generalized Reduced Gradient Method
Chih-Wei Lin,Ke-Fang Hsu,Jung-Min Hwang,

The phosphor with blue chip model is constructed and linked with generalized reduced gradient method in spreadsheet for the LED spectrum control. The parameters of the model are calibrated or defined with the dispenser LED prototype measurement results. Finally, the phosphor model can be used for specific spectrum control.

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Paper No.  2014-Fri-P0803-P011
Mei-Tan Wang 3D micro-molded LED light engine
Mei-Tan Wang,

3D micro-scaled lenses on light-emitting diodes (LEDs) light engine are realized through ultra-precision injection molding in this study. The geometrical construction of single lens is fabricated using 5-axis machining and has pitch from sub-millimeter to micrometer on curved surface. The radiation pattern is designed to 42∘and the radius of lens is less than 3mm.

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Paper No.  2014-Fri-P0803-P012
Fu-Jun Lu Reducing dark area of LED tube lamps
Fu-Jun Lu,Cheng-Chung Jaing,Hung-I Li,Chien-Jen Tang,Yeuh-Yeong Liou,

An improvement on reducing the dark area of LED tube lamps has been made using triangular microlens arrays. The influence of nine different heights of triangular microlens on optical power distributions of LED tube lamps from 75 to 90 degrees in the observed planes has been investigated.

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Paper No.  2014-Fri-P0803-P013
Uan-De Sue Anti-glare LED lamps with adjustable illumination light field
Uan-De Sue,Hsiang-Chen Wang,

We introduce a type of LED light-gauge steel frame lamp with an adjustable illumination light field that does not require a diffusion plate. Base on the Monte Carlo ray tracing method, this lamp has a good glare rating (GR) of 17.5 at 3050 lm. Compared with the traditional LED light-gauge steel frame lamp (without diffusion plate), the new type has low GR. The adjustability of the illumination light field could improve the zebra effect caused by the inadequate illumination light field of the lamp. Meanwhile, we adopt the retinal image analysis to discuss the influence of GR on vision. High GR could reflect stray light on the retinal image, which will reduce vision clarity and hasten the feeling of eye fatigue.

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Paper No.  2014-Fri-P0803-P014
Kung-Cheng Ho Device and materials characteristics of GaN-based LEDs using In-doped ZnO transparent conductive layers grown by atomic layer deposition
Kuo-Yi Yen,Chi-Ying Hsiao,Chun-Wei Li,Chien-Hua Chou,Ko-Ying Lo,Tzu-Pei Chen,Kung-Cheng Ho,Bo-Yan Chen,Jyh-Rong Gong,

The implementation of N2-annealed ALD-grown IZO in an InGaN/GaN MQW LED results in light extraction enhancement and forward voltage reduction. At 20 mA operating condition, N2-annealed n-IZO-coated InGaN/GaN MQW LED was found to show a smaller ideality factor than that of the same LED structure having an ITO TCL.

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Paper No.  2014-Fri-P0803-P015
Yang Yen Ting Influences of phosphor sedimentation phenomenon of Phosphor-Converted White Light Emitting Diodes
YangYen Ting,ShihTien Tsorng,

The effect of phosphor sedimentation in silicone during isothermal curing on color rendering for WLED is investigated. The CCT changed from 5115K to 5887K and the power efficiency degraded 3.5% under different sedimentation conditions have been observed.

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Paper No.  2014-Fri-P0803-P016
chi-min Liu Simulation and fabrication of heterogeneous microlenses array
chi-min Liu,

We calculated the profile of convex and concave microlenses with Lighttool®, and fabricated the heterogeneous microlenses array by using inkjet-printing and 3D-printer. We placed the microlens array on top of LEDs, so as to make the light of LEDs more evenly. Finally, we succeed in constructing the microlens array and an energy saving device

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Paper No.  2014-Fri-P0803-P017
Hwang Jung-Min Optical-electrical-thermal coupling analysis for 3D micro-molded LED
Hwang Jung-Min,Wang Mei-Tan,

To get the optimized cost-performance for operating the LEDs, well understanding and well-controlled of the optical-electrical-thermal coupling characteristics were the key issues. In this paper, the coupling model of the optical-electrical-thermal with commercial LED’s datasheet was proposed. The coupling effect of the 3D micro-molded LED was measured and analyzed

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Paper No.  2014-Fri-P0803-P018
Tien-Lung Chiu Carbazole-Triazole Derivative Host for High Efficiency Blue Phosphorescence Organic Light-Emitting Diode
Tien-Lung Chiu,Hsin-Jen Chen,Yu-Hsuan Hsieh,Man-kit Leung,Chi-Feng Lin,Jiun-Haw Lee,

A new carbazole triazole derivative, CbzTAZ, was synthesized to be the host of emitting layer doped with FIrpic inside an efficient blue phosphorescence organic light-emitting diode. This OLED shows the excellent external quantum efficiency of more than 24%.

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Paper No.  2014-Fri-P0803-P019
Yi-Hsin Lan Blue phosphorescent organic light-emitting diode with different electron transport materials
Yi-Hsin Lan,Jau-Jiun Huang,Man-kit Leung,Tien-Lung Chiu,Chi-Feng Lin,Jiun-Haw Lee,

In this paper, we demonstrated blue phosphorescence organic light-emitting diode (OLED) with two different electron transporting materials. The highest current efficiency was 23.01 cd/A, and the driving voltage is 9.54 V at 10 mA/cm2.

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Paper No.  2014-Fri-P0803-P020
Po-Ruei Yan Synthesis of Ionic Polyfluorene Derivatives Containing Iridium Complexes as Active Layers in White Light-Emitting Electrochemical Cells
Bao-Ren Chen,Po-Ruei Yan,Sheng-Hsiung Yang,Yi Chang,Hai-Ching Su,

Ionic polyfluorene derivatives containing iridium complexes were synthesized. The ionic polymers with PF6 − counterions have better thermal stabilities than those with Br− ones. White light-emitting electrochemical cells based on those Ionic polyfluorenes were fabricated and evaluated.

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Paper No.  2014-Fri-P0803-P021
Tsung-Lin Lu Experimental analysis of far-field region of non-CSU LED Light Source
Tsung-Lin Lu,Bo-Song Chen,Tsung-Xian Lee,

In general, the distance of far-field of a light source was defined by the intensity distribution (ID) base on the color spatial distribution (CSD) was assumed uniform. This study compared the relationship between far-field decided by ID and CSD for a non-CSU LEDs. From the results, we found that the far-field decided by CSD was farer than ID.

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Paper No.  2014-Fri-P0803-P022
Jhih-Wei Deng Efficiency Droop in GaN Light-Emitting Diodes Caused by Auger Recombination and Enhanced by Current Crowding Effect
Jenq-Shinn Wu,Jhih-Wei Deng,

We simulate the radiative and non-radiative recombinations in GaN LEDs. It’s clearly shown that, as confirmed by experimental results published elsewhere, Auger recombination dominates the efficiency droop behavior. Besides, current crowding enhances Auger recombination, causing more efficiency droop. Increasing the thickness and doping concentration of the n-GaN buffer layer eases off efficiency droop.

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Paper No.  2014-Fri-P0803-P023
Horng son Wang Evaluation of Perceived Brightness of LED Array Lighting
Horng son Wang,Tsung-Xian Lee,

The purpose of this study was to investigated the evaluation of perceived brightness with different light source-spacing under same luminance level. The interaction of planar light source luminance, spacing of point light source array and viewing distance were investigated. Accordingly, the optimized luminance and arrangement of LED array lighting can be obtained.

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Paper No.  2014-Fri-P0803-P024
Lung-Chien Chen Fabrication of white light-emitting diodes with yellow phosphor on PDMS
Kai-Chieh Liang,Ting-Chun Hsv,Jyun-Wei Chen,Wen-Wei Lin,Lung-Chien Chen,

In this study, we develop a method to directly transfer GaN-based light-emitting diode (LED) from sapphire onto flexible substrates by laser lift-off (LLO) process. Polydimethylsiloxane (PDMS) was prepared as a flexible substrate which had the advantages of flexible, low cost, good chemicophysical properties and good optically transparent. We have added the yellow phosphor (cerium doped yttrium aluminum garnet, YAG: Ce) in PDMS and caused the GaN-based LED to send out the white photosource directly. In the experiment, through the phosphor doped with different concentrations and observed electro-optical properties of structures to achieve the effect of white light emitting diode device.

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