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Chen K.-J.,National Chiao Tung University | Han H.-V.,National Chiao Tung University | Lin B.-C.,National Chiao Tung University | Chen H.-C.,National Chiao Tung University | And 10 more authors.
IEEE Electron Device Letters | Year: 2013

This letter examines a hybrid phosphor structure for white light-emitting diodes. The hybrid phosphor structure produces more efficient luminosity and more uniform angular correlated color temperature The lumen output produced was higher than that produced by dispense and conformal phosphor structures. Therefore, there sults show that the hybrid phosphor structure can be used in solid-state lighting. © 2013 IEEE. Source


Taloni A.,CNR Institute for Energetics and Interphases | Yeh J.-W.,Academia Sinica, Taiwan | Chou C.-F.,Academia Sinica, Taiwan | Chou C.-F.,Research Center for Applied science
Macromolecules | Year: 2013

We provide a scaling framework describing the different regimes attained by a slit-confined polymer, undergoing an external pulling force f el,slit. Linear and nonlinear force-extension relations are discussed in the limit of small and large elongations, resorting to the notion of self-avoiding pancakes. The crossover to a channellike behavior allows to explain the scaling of fel,slit as a function of the confinement h observed in recent tug-of-war experiments. The theoretical analysis provides also a qualitative explanation of DNA relaxation and coil-stretch transition experiments performed in nanoslits. © 2013 American Chemical Society. Source


Lin B.-C.,National Chiao Tung University | Chen K.-J.,National Chiao Tung University | Han H.-V.,National Chiao Tung University | Lan Y.-P.,National Chiao Tung University | And 6 more authors.
IEEE Photonics Technology Letters | Year: 2013

InGaN/GaN light-emitting diodes (LEDs) with graded-composition AlGaN/GaN superlattice (SL) electron blocking layer (EBL) were designed and grown by metal-organic chemical vapor deposition. The simulation results demonstrated that the LED with a graded-composition AlGaN/GaN SL EBL have superior hole injection efficiency and lower electron leakage over the LED with a conventional AlGaN EBL or normal AlGaN/GaN SL EBL. Therefore, the efficiency droop can be alleviated to be ~20%from maximum at an injection current of 15-120 mA, which is smaller than that for conventional AlGaN EBL (30%). The corresponding experimental results also confirm that the use of a graded-composition AlGaN/GaN SL EBL can markedly enhance the light output power by 60%. © 1989-2012 IEEE. Source


Wei H.-Y.,National Taiwan University | Huang J.-H.,Academia Sinica, Taiwan | Ho K.-C.,National Taiwan University | Ho K.-C.,National Chiao Tung University | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2010

We have developed polymer solar cells featuring a buffer layer of polythiophene (PT) sandwiched between the active layer and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. We attribute the improvement in power conversion efficiency of these polymer solar cells, relative to that of those based on poly(3-hexylthiophene):[6,6]-phenyl- C 61-butyric acid methyl ester (P3HT:PCBM), to a reduction in the degree of carrier recombination at the junction interface. Because the conductivity and the energy level of PT can be tuned simply by applying a bias to it in an electrolytic solution, we also investigated the effect of the energy level on the devices' performances. The power conversion efficiency of a solar cell containing a PT buffer layer reached 4.18% under AM 1.5 G irradiation (100 mW/cm 2). © 2010 American Chemical Society. Source


Huang J.-H.,Research Center for Applied science | Ibrahem M.A.,Research Center for Applied science | Ibrahem M.A.,University of Taipei | Chu C.-W.,Research Center for Applied science | Chu C.-W.,National Chiao Tung University
Progress in Photovoltaics: Research and Applications | Year: 2015

In this study, an air-stable bulk heterojunction organic solar cell demonstrated by utilization of titanium oxide (TiO2) nanoparticles as a hole blocking layer was prepared through high-energy grinding method. The large clumps of the anatase TiO2 underwent deaggregation to form a stable dispersed solution during the grinding process. The resultant suspension can form a uniform and smooth TiO2 film through spin coating on various substrates. Because of substantial oxygen and water protection effect of TiO2 thin film, the bulk heterojunction solar cells exhibit a significant long-term stability. It is also found that the cell performance can be promoted dramatically after ultraviolet activation. The mechanism responsible for the enhanced cell efficiency was also investigated. This solution-based method does not require surfactants, thus preserving the intrinsic electronic and optical properties of TiO2 that makes these proposed buffer layers quite attractive for next-generation flexible devices appealing high conductivity and transparency. Copyright © 2014 John Wiley & Sons, Ltd. Source

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