Browsing by Author "Yeh, Yun-Ling"

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A Highly Efficient Hybrid GaAs Solar Cell Based on Colloidal-Quantum-Dot-Sensitization
(2014-07-18)
Han, Hau-Vei
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Lin, Chien-Chung
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Tsai, Yu-Lin
;
Chen, Hsin-Chu
;
Chen, Kuo-Ju
This paper presents a hybrid design, featuring a traditional GaAs-based solar cell combined with various colloidal quantum dots. This hybrid design effectively boosts photon harvesting at long wavelengths while enhancing the collection of photogenerated carriers in the ultraviolet region. The merits of using highly efficient semiconductor solar cells and colloidal quantum dots were seamlessly combined to increase overall power conversion efficiency. Several photovoltaic parameters, including short-circuit current density, open circuit voltage, and external quantum efficiency, were measured and analyzed to investigate the performance of this hybrid device. Offering antireflective features at long wavelengths and luminescent downshifting for high-energy photons, the quantum dots effectively enhanced overall power conversion efficiency by as high as 24.65% compared with traditional GaAs-based devices. The evolution of weighted reflectance as a function of the dilution factor of QDs was investigated. Further analysis of the quantum efficiency response showed that the luminescent downshifting effect can be as much as 6.6% of the entire enhancement of photogenerated current.
Embedded InN Dot-Like Structure within InGaN Layers Using Gradient-Indium Content in Nitride-Based Solar Cell
(2013)
Hsu, Lung-Hsing
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Lin, Chien-Chung
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Tan, Ming-Hsuan
;
Yeh, Yun-Ling
;
Lin, Da-Wei
The novel design of embedded InN dot-like structure within InGaN was useful as an absorption layer in photovoltaic (PV) cells. We constructed the simulation model by employing the commercial software APSYS (R) and integrating the absorption coefficient of thin InN materials fabricated by metal organic vapor deposition (MOCVD). The model of simulating gradient Indium content of InGaN used as transition interface between InN and GaN was investigated. The results exhibit utilizing the effective variation of Indium content and suitable thickness to approach the optimal characteristic of hybrid InN/InGaN structure within solar cells shall be anticipated to enhance the performance of current nitride-based solar cells.
Spectrally Dependent Performance of Hybrid Colloidal Quantum Dots GaAs Solar Cells
(2013)
Han, Hau-Vei
;
Lin, Chien-Chung
;
Chen, Hsin Chu
;
Tsai, Yu-Lin
;
Yeh, Yun-Ling
Because of the global warming effect and energy crisis, the usage of solar energy gets more and more important in recent years. In particular, GaAs-based solar cells have been regarded as a promising candidate to provide high power conversion efficiency because of their direct band gap and strong absorption over the entire visible part of the solar spectrum. In this work, we demonstrate a hybrid design of traditional GaAs-based solar cell combined with colloidal quantum dots. Several photovoltaic parameters were enhanced, including the short circuit current density, fill factor, and power conversion efficiency, which were measured under white light illumination similar to the solar spectrum. With anti-reflective feature at long wavelength and down-conversion at high energy photons, the quantum dot effectively enhance the overall power conversion efficiency by as high as 25% compared to traditional GaAs-based device. The evolution of short-circuit current density and weighted reflectance as a function of the dilution factor of three type QDs has been investigated. The dilution factors of quantum dots solution also have been optimized for single junction GaAs devices. We also use the EQE enhancement spectrum to further distinguish between the photon down-conversion and antireflection capability of QDs. Finally, we believe this technology shall be a great candidate for next generation of highly efficient photovoltaic devices.