Browsing by Author "Wang, Hsun-Wen"

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Enhanced efficiency for c-Si solar cell with nanopillar array via quantum dots layers
(2011-09-12)
Chen, Hsin-Chu
;
Lin, Chien-Chung
;
Han, Hao-Wei
;
Tsai, Yu-Lin
;
Chang, Chia-Hua
The enhanced efficiency of the crystalline silicon (c-Si) solar cell with nanopillar arrays (NPAs) was demonstrated by deployment of CdS quantum dots (QDs). The NPAs was fabricated by the colloidal lithography and reactive-ion etching techniques. Under a simulated one-sun condition, the device with CdS QDs shows a 33% improvement of power conversion efficiency, compared with the one without QDs. For further investigation, the excitation spectrum of photoluminescence (PL), absorbance spectrum, current-voltage (I-V) characteristics, reflectance and external quantum efficiency of the device was measured and analyzed. It is noteworthy that the enhancement of efficiency could be attributed to the photon down-conversion, the antireflection, and the improved electrical property. (C) 2011 Optical Society of America
High Extraction Efficiency of GaN-Based Vertical-Injection Light-Emitting Diodes Using Distinctive Indium-Tin-Oxide Nanorod by Glancing-Angle Deposition
(2011-05-01)
Tsai, Min-An
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Wang, Hsun-Wen
;
Yu, Peichen
;
Kuo, Hao-Chung
;
Lin, Shiuan-Huei
The enhanced light extraction and reduced forward voltage of a GaN-based vertical injection light emitting diode (VI-LED) with an indium-tin-oxide (ITO) nanorod array were demonstrated. The ITO nanorod array was fabricated by the glancing-angle deposition method. The employment of ITO nanostructures amplified not only the broadband transmission but also the current spreading. The optical output power of GaN-based VI-LEDs with ITO nanorods was enhanced by 50% compared with a conventional VI-LED at an injection current of 350 mA. The extraction efficiency was dramatically raised from 62 to 93% by the surface ITO nanorods. We also optimized the extraction efficiency of the GaN-based VI-LED with an ITO nanorod array by tuning the thickness of the n-GaN top layer via three-dimensional finite difference time domain (3D-FDTD) simulation. (C) 2011 The Japan Society of Applied Physics
Influence of barrier thickness modulation of InGaN/GaN MQW solar cells
(2013)
Hsieh, Chi-Chang
;
Lai, Fang-, I
;
Wang, Hsun-Wen
;
電子物理學系
;
Department of Electrophysics
The influence of band structure and indium composition of stepping layer are numerically investigated on the photovoltaic characteristics of InGaN/GaN MQW solar cell. In this study, the barrier structure and indium composition of inserting stepping layer leads to a substantial influence in the cell efficiency and output short circuit current density. It reveals that L-structure in barrier modulation would contribute to fine carrier collection and increase the conversion efficiency. Moreover, L-structure barrier modulation would effectively reduce the recombination rate in wells near p-GaN side where dominant recombination in well regions is. Barrier height of stepping layers plays an important role in high carrier collection that keeps high conversion efficiency. However, the optimal 5% indium composition of L-structure 14-pair MQW solar cell would obtain the best performance.
Numerical Study of In0.15Ga0.85N/GaN MQW Solar Cells with varying well band structure
(2013)
Wang, Hsun-Wen
;
Hsieh, Chi-Chang
;
Lai, Fang-I
;
Lin, Shiuan-Huei
;
Kuo, Hao-Chung
The photovoltaic properties of 14 pairs In0.15Ga0.85N/GaN multiple quantum well solar cells with varying indium composition of QW are investigated numerically. The simulation results show that smooth well structure of energy band can be reduce carrier confinement and the recombination to enhance photo-current generation. This helpful design is easy to improve carrier transport to collection. And the optimal In0.15Ga0.85N/GaN MQW solar cell had V-oc of 2.37V, J(sc) of 0.73, and the efficiency of 0.79%, which the efficiencies is enhanced 69.2 % to reference cell.
Projected Efficiency of Polarization-Matched p-InxGa1-xN/i-InyGa1-yN/n-GaN Double Heterojunction Solar Cells
(2013-07-01)
Wang, Hsun-Wen
;
Yu, Peichen
;
Wu, Yuh-Renn
;
Kuo, Hao-Chung
;
Chang, Edward Yi
Traditional p-GaN/i-InGaN/n-GaN double heterojunction solar cells have limited power conversion efficiency due to large polarization charges that accumulate at the heterojunction interfaces, leading to severe band bending that, in turn, hinders the carrier transport. In this study, we proposed the use of a p-type InGaN layer to reduce the polarization field and projected the power conversion efficiencies of p-InxGa1-xN/i-InyGa1-yN/n-GaN double heterojunction solar cells that are grown on a c-facet sapphire substrate with various indium components. Numerical simulations predict that a maximal power conversion efficiency that is close to 7% with a short-circuit current density of 4.05 mA/cm(2) and an open-circuit voltage of 1.94 V can be achieved with a p-In0.2Ga0.8N/i-In0.2Ga0.8N/n-GaN structure due to a polarization-matched p-i interface. Further efficiency enhancement with a higher indium composition over 20% is also possible via the redistribution of the built-in potential with n-GaN doping.
Simulation of Grading Double Hetero-junction non-polar InGaN Solar cell
(2012)
Wang, Hsun-Wen
;
Yu, Pei-Chen
;
Han, Hau-Vei
;
Lin, Chien-Chung
;
Kuo, Hao-Chung
The characteristics of non-polar double heterojunction GaN/InxGa1-xN solar cells with various indium contents are numerically investigated. By smoothing the interface band edge offset with graded junction, the maximum efficiency reached 24.32 % as In0.6Ga0.4N. (C) 2012 Optical Society of America
Simulation of Grading Double Hetero-junction non-polar InGaN Solar cell
(2013)
Wang, Hsun-Wen
;
Yu, Pei-Chen
;
Han, Hau-Vei
;
Lin, Chien-Chung
;
Kuo, Hao-Chung
In this study, the characteristics of non-polar double heterojunction GaN/ InxGa1-xN solar cells with various indium contents are numerically investigated under AM 1.5 global spectrum using finite element analysis. By smoothing the interface band edge offset with graded junction, we see the enhancement on short circuit current and power conversion efficiency. The maximum efficiency of the simulation results reached 24,32 % when the major absorption region contains 65% of indium composition..