Browsing by Author "Chen, H. C."

Now showing 1 - 20 of 24

A Full-Color, White Light Emission of Quantum-Dot-Based Display Technology Using Pulsed Spray Method with Distributed Bragg Reflector
(2012)
Chen, K. J.
;
Chen, H. C.
;
Lin, C. C.
;
Tsai, H. H.
;
Tsai, K. A.
A colloidal quantum dot light-emitting multi-layer structure with HFO2/SiO2 distributed Bragg reflector is manufactured by pulse spray method. A pure white light with strong enhancement due to better utilization of UV pump was demonstrated. (C)2012 Optical Society of America
A HIGHLY EFFICIENT HYBRID CDS-GAAS SOLAR CELL
(2012)
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Han, H. V.
;
Yu, Peichen
A novel design of hybrid solar cell combining traditional GaAs-based solar cell with colloidal CdS quantum dots (ODs) is demonstrated. By applying CdS ODs on the surface of GaAs device, we can obtain an effective antireflection coating at long wavelength. Moreover, due to its strong absorption at ultraviolet range and efficient light emission at blue photon, CdS quantum dots can down-convert the high-energy UV photons into visible ones, which are more easily to be collected in GaAs solar cell. The short circuit current and power conversion efficiency of this new device increases by 21% and 18.9%, respectively, when we compare them to the uncoated GaAs solar cell. An increase of the surface photoconductivity was also detected due to UV presence, and the fill factor of the CdS ODs solar cell can be improved accordingly.
Accuracy analysis of the percentile method for estimating non normal manufacturing quality
(2007)
Wu, Chien-Wei
;
Pearn, W. L.
;
Chang, C. S.
;
Chen, H. C.
;
工業工程與管理學系
Vannman ( 1995) proposed a superstructure C-p(u, v) of capability indices for processes with normal distributions, which include C-p, C-pk, C-pm, and C-pmk as special cases. Pearn and Chen (1997) considered a generalization of C-p(u, v), called C-Np(u, v), to cover processes with non normal distributions. Pearn and Chen ( 1997) also proposed a sample percentile estimator for the generalization C-Np(u , v). In this article, we investigate the performance of the sample percentile estimator. We perform some simulation study, which covers the normal distribution and various non normal distributions including the uniform distribution, chi-square distribution, student's t distributions, F distribution, beta distribution, gamma distribution, Weibull distribution, lognormal distribution, triangular distribution, and Laplace distribution, with selected parameter values. Extensive simulation results, comparisons, and analysis are provided.
Conversion Efficiency Enhancement of GaN/In(0.11)Ga(0.89)N Solar Cells With Nano Patterned Sapphire and Biomimetic Surface Antireflection Process
(2011-09-15)
Wang, H. W.
;
Chen, H. C.
;
Chang, Y. A.
;
Lin, C. C.
;
Han, H. W.
In this study, p-i-n double-heterojunction GaN/In(0.11)Ga(0.89)N solar cells grown by metal-organic chemical vapor deposition on pattern sapphire substrate are presented. The solar cell with standard process has a conversion efficiency of 3.1%, which corresponds to a fill factor of 58%, short circuit current density of 2.86 mA/cm(2), and open circuit voltage of 1.87 V under AM1.5G illumination. To further improve the conversion efficiency of the GaN/In(0.11)Ga(0.89)N solar cells, two-dimensional polystyrene nanospheres were deposited and self-organized as mask in the anisotropic inductively coupled plasma reactive ion etching process to form a biomimetic surface roughing texture. The surface morphology of the solar cell shows a periodically hexagonal bead pattern and the beads are formed in a diameter of 160 nm with a period of 250 nm. An increase of 15% in short circuit current density is found, thus improving the conversion efficiency to 3.87%. If we optimize the structure for 180 nm of the height and 375 nm of the period, a 10% gain can be expected when compared to the current structure.
Conversion Efficiency Enhancement of GaN/In0.11Ga0.89N Solar Cells With Nano Patterned Sapphire and Biomimetic Surface Antireflection Process
(2011-09-15)
Wang, H. W.
;
Chen, H. C.
;
Chang, Y. A.
;
Lin, C. C.
;
Han, H. W.
In this study, p-i-n double-heterojunction GaN/In0.11Ga0.89N solar cells grown by metal-organic chemical vapor deposition on pattern sapphire substrate are presented. The solar cell with standard process has a conversion efficiency of 3.1%, which corresponds to a fill factor of 58%, short circuit current density of 2.86 mA/cm(2), and open circuit voltage of 1.87 V under AM1.5G illumination. To further improve the conversion efficiency of the GaN/In0.11Ga0.89N solar cells, two-dimensional polystyrene nanospheres were deposited and self-organized as mask in the anisotropic inductively coupled plasma reactive ion etching process to form a biomimetic surface roughing texture. The surface morphology of the solar cell shows a periodically hexagonal bead pattern and the beads are formed in a diameter of 160 nm with a period of 250 nm. An increase of 15% in short circuit current density is found, thus improving the conversion efficiency to 3.87%. If we optimize the structure for 180 nm of the height and 375 nm of the period, a 10% gain can be expected when compared to the current structure.
Design of Highly Absorption Structure by Flatted ITO Patterned Substrate for Thin Film a-Si Solar Cells
(2012)
Han, H. V.
;
Shih, H. S.
;
Chen, H. C.
;
Tsai, Y. L.
;
Yu, P. C.
The patterned substrate is a flatted structure which composed with two materials to enhance the absorption of a-Si solar cell. We optimized this structure by simulation method and find it has good omnidirectional antireflection effect. (C) 2012 Optical Society of America
Development of optimised carrier sequence in MCU-based random-frequency PWM
(2007-01-01)
Chen, H. C.
;
Chang, Y. C.
;
Huang, C. K.
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The effect of the carrier sequences on the voltage spectrum of MCU(microcontroller)based random-frequency pulse-width modulation (RFPWM) is presented. To optimise the carrier sequence efficiently, first all possible sequences are classified into groups according to the time-shift and time-reverse properties of the Fourier transform. Then, some evaluation indexes are proposed to obtain the optimal sequence quickly with the end of a personal computer (PC). Finally, some optimised carrier sequences with only two carrier frequencies are recommended. The experimental results also indicate that we should pay more attentions to the carrier sequences than to the selection of carrier frequency and on the numbers of carrier frequencies.
Dissociation dynamics of anionic and excited neutral fragments of gaseous SiCl(4) following Cl 2p and Si 2p core-level excitations
(2008-10-08)
Chen, J. M.
;
Lu, K. T.
;
Lee, J. M.
;
Chou, T. L.
;
Chen, H. C.
The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl(4) following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photon-induced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states) doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl4 lead to a remarkably enhanced production of anionic, Si-and Cl(-), fragments and excited neutral atomic, Si*, fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.
Dissociation dynamics of anionic and excited neutral fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations
(2008-10-08)
Chen, J. M.
;
Lu, K. T.
;
Lee, J. M.
;
Chou, T. L.
;
Chen, H. C.
The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photon-induced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states) doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl4 lead to a remarkably enhanced production of anionic, Si-and Cl-, fragments and excited neutral atomic, Si*, fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.
Effect of the Thermal Characteristics of Phosphor for the Conformal and Remote Structures in White Light-Emitting Diodes
(2013-10-01)
Chen, K. J.
;
Lin, B. C.
;
Chen, H. C.
;
Shih, M. H.
;
Wang, C. H.
The influence of the thermal effect of phosphor for conformal and remote structures in white light-emitting diodes was investigated using the junction and phosphor temperatures. Comparing the measured temperatures with IR thermometer, the remote structure has a higher phosphor temperature than the conformal structure. This result indicates that the phosphor in the conformal structure has demonstrated superior conduction because of the high thermal conductivity in surrounding. Furthermore, thermal distribution in the simulation results has shown to have favorable agreement with the experimental results. Consequently, the lifetime measurement is shown to verify the results of the simulation and experiment for both structural types.
EFFICIENCY ENHANCEMENT IN SINGLE JUNCTION INGAP SOLAR CELLS BY USING SELF-ASSEMBLED NANOSPHERES
(2010)
Chen, H. C.
;
Tsai, Y. L.
;
Wang, H. W.
;
Tsai, M. A.
;
Tseng, P. C.
A single-junction InGaP solar cells with polystyrene (PS) nanospheres on the surface has been developed. The self-assembly of PS nanospheres is one of the simplest and the fastest methods with which to build a 20 closely packed periodic structure. Based on the scattering of the PS nanospheres, the light path length can be increased. As compared to the InGaP solar cells without PS nanospheres on the top surface the standard process. An increase short-circuit current form 8.93% to 10.31% is improved when a single-junction InGaP solar cells with PS nanospheres. The conversion efficiency measured can also be improved from 8.79% to 9.71%. The single-junction InGaP solar cell with PS nanospheres was achieved.
Efficiency Enhancement in Single-Junction InGaP Solar Cells by Using Self-Assembled Nanospheres
(2011-06-01)
Chen, H. C.
;
Lin, C. C.
;
Wang, H. W.
;
Tsai, M. A.
;
Tseng, P. C.
A single-junction InGaP solar cell with polystyrene (PS) nanospheres on the surface has been developed. The self-assembly of PS nanospheres is one of the simplest and the fastest methods with which to build a 2-D closely packed periodic structure. Due to the scattering of the PS nanospheres, the light path length can be increased when compared to the InGaP solar cells without PS nanospheres on the top. An increase short-circuit current from 8.93 to 10.31 mA is improved when a single-junction InGaP solar cell is coated with PS nanospheres. The conversion efficiency measured can also be improved from 8.79% to 9.71%. The single-junction InGaP solar cell with PS nanospheres was achieved.
EFFICIENCY ENHANCEMENT InGaP/GaAs DUAL-JUNCTION SOLAR CELL WITH SUB-WAVELENGTH ANTIREFLECTION NANOROD ARRAYS
(2010)
Wang, H. W.
;
Tsai, M. A.
;
Chen, H. C.
;
Tsai, Y. L.
;
Tseng, P. C.
The enhanced conversion efficiency of the InGaP/GaAs dual-junction solar cell was demonstrated antireflection nanorod arrays. After self-assembled Ni clusters, the nanorod arrays were fabricated by inductively-coupled-plasma reactive ion etching. The conversion efficiency were measured under one-sun air mass 1.5 global illuminations at room temperature. The short current of the nanorod arrays cell was enhanced 10.0% and the efficiency was enhanced 10.8%. We were also studied the light absorption efficiencies of the top InGaP and bottom GaAs cells under the influence of nanorod arrays. Surface nanorod arrays were not only as antireflection layers but also scattering sources. The nanorod arrays structure can be significant improved the maximum conversion efficiency.
Enhance current density and light trapping effect in a-Si thin film solar cells by flexible textured PDMS film
(2013)
Han, H. V.
;
Chen, H. C.
;
Tsai, Y. L.
;
Lin, C. C.
;
Kuo, H. C.
The light trapping effect of a textured polydimethylsiloxane (PDMS) film on the suppression of surface reflection in a-Si:H solar cell is investigated. The angular dependence of scattered light from this PDMS film was measured and a symmetric scattering intensity peak was found at +/- 20(0). The enhancement of power conversion efficiency in the a-Si:H solar cell with textured PDMS film can reach 16.37% compared to the a-Si:H solar cells without textured PDMS film. This improvement is mainly attributed to the enhanced efficiencies of light trapping and scattering. Such a design concept and fabrication process can be widely adapted to a variety of thin film solar cells.
Enhanced Omnidirectional Photon Coupling via Quasi-Periodic Patterning of Indium-Tin-Oxide for Organic Thin-Film Solar Cells
(2011-01-01)
Tseng, P. C.
;
Hsu, M. H.
;
Chen, H. C.
;
Tsai, M. A.
;
Yu, Peichen
Enhanced optical coupling with respect to all incident angles via an indium tin oxide quasi-periodic structure (ITO-QPS) for organic thin-film solar cells was demonstrated. The cell @2010 Optical Society of America
Enhancement of Light Harvesting and Power Conversion Efficiency in GaAs solar cells using flexible textured PDMS film
(2013-01-01)
Han, H. V.
;
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Yeh, Y. L.
Light trapping of textured polydimethylsiloxane films for antireflection is investigated. The efficiency of GaAs solar cell with textured PDMS film reach 28% enhancement. Numerical analysis successfully rebuilds the surface profile close to the real situation. (C) 2013 Optical Society of America
Highly Efficient GaAs Solar Cells with Dual Layer of Quantum Dots And A Flexible PDMS Film
(2012)
Lin, Chien-chung
;
Chen, H. C.
;
Chen, K. J.
;
Han, H. V.
;
Kuo, H. C.
High performance of GaAs solar cell with dual layer quantum dots separated by flexible polydimethylsiloxane film was demonstrated. By this scheme, the efficiency increased by 22 %, compared to the cell without QDs. (C) 2012 Optical Society of America
Improve GaAs Solar Cells Efficiency by Using High-transmittance Textured PDMS Film
(2013)
Han, H. V.
;
Chen, H. C.
;
Lin, C. C.
;
Tsai, Y. L.
;
Kuo, H. C.
We demonstrate the GaAs solar cells which utilize the high-transmittance textured polydimethylsiloxane (PDMS) film can outstanding increase the short circuit current density and power conversion efficiency of solar cells. The transmittance of PDMS film is exceeded 90%, which can pass through almost all the light of GaAs Solar cells can be absorbed. We used a special imprint technology to let the PDMS film possess a highly textured surface. Then we measured the characteristics of textured PDMS film and found out that it has a very excellent Haze performance. The effect of flexible textured PDMS film on the suppression of surface reflection in GaAs solar cells is also investigated. The presented technology provides an inexpensive surface anti-reflection process, which can potentially replace typically complex anti-reflection coating (ARC) layer. The GaAs solar cells with textured PDMS layer can effectively enhance the short-circuit current density from 22.91 to 26.54 mA/cm(2) and the power conversion efficiency from 18.28 to 21.43 %, corresponding to a 17 % enhancement compared to the one without textured PDMS. The open-circuit voltage (V-oc) and the fill-factor (FF) of GaAs solar cells exhibit negligible change, because the textured PDMS film was pasted up on the surface of GaAs solar cells and did not interfere with the diode operation. At the same time, we observed through the EQE measurement that the textured PDMS film not only proved wonderful light scattering effect but also generated more electron-hole pairs in all absorption spectrum range. Finally, through this simple PDMS process, we believe this technology shall be a great candidate for next generation of highly efficient and low-cost photovoltaic devices.
Improvement of Angular-dependent CCT Uniformity by ZrO2 Nano-particles in Remote Phosphor White LEDs
(2012)
Chen, H. C.
;
Chen, K. J.
;
Wang, C. H.
;
Tsai, H. H.
;
Lin, C. C.
The superior uniformity of angular-dependent CCT white LEDs have been investigated by ZrO2-type remote phosphor structure. This novel structure reduces angular-dependent CCT deviations from 1000K to 420K in range of -70 to 70 degrees. (C)2012 Optical Society of America
Improvement of lumen efficiency in white light-emitting diodes with air-gap embedded package
(2012-05-01)
Chen, H. C.
;
Chen, K. J.
;
Lin, C. C.
;
Wang, C. H.
;
Yeh, C. C.
In this paper, white light-emitting diodes (LEDs) with air-gap embedded package were proposed and fabricated by a simple method including pulsed spray coating. The lumen efficiency of air-gap embedded LED was enhanced by 8.8% at driving current of 350 mA, compared to conventional remote phosphor white LED. This improvement was due to the enhanced utilization of blue and yellow rays, which were confirmed by pulse current-dependent correlated color temperature (CCT). The utilization efficiency of blue rays was enhanced by 12.4% due to the embedded air-gap layer. The simulation results performed by Monte-Carlo ray tracing method agreed with our experiments, which showed enhancement in lumen efficiency and similar CCT. Finally, the electric field intensity versus different thickness for air-gap and no air-gap embedded white LED was calculated to check the incident blue rays trapped in phosphor layer. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.