Browsing by Author "Nguyen-Hong Quan"

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Broadband antireflection sub-wavelength structure of InGaP/InGaAs/Ge triple junction solar cell with composition-graded SiNx
(2015-05)
Chung, Chen-Chen
;
Lo, Hsiao-Chieh
;
Lin, Yen-Ku
;
Yu, Hung-Wei
;
Binh Tinh Tran
This work reports a fabrication strategy to improve the antireflective ability of a InGaP/GaAs/Ge triple-junction solar cell, by combining a nano-templating technique and a chemical-synthesis approach. SiH4 and N-2 were used as ammonia-free reaction gases in a plasma-enhanced chemical vapor deposition (PECVD) to prepare Si3N4 as an original antireflective coating (ARC) layer with better chemical stability. Composition-graded SiNx was successfully integrated with sub-wavelength structure by modulating SiH4/N-2 ratio during PECVD deposition, and followed by a controllable gold-nanoparticle masking technique on top of the solar cell. Finite-difference time-domain solution was employed to simulate and optimize the aspect-ratio of the ARC, under the condition of variable refractive index over a broad wavelength window, and followed by the masking technique to obtain the desired ARC dimension. This enabled a low light reflectance (<10%) over a broad spectral bandwidth (300-1800 nm) for the solar cell with excellent stability, because of the triple advantages of structural optimization, better chemical stability and graded refractive index of the ARC. The solar cell\'s performance was tested and showed great competitiveness to those of forefront studies, suggesting the feasibility of the proposed technology.
Efficiency improvement of InGaP/GaAs/Ge solar cells by hydrothermal-deposited ZnO nanotube structure
(2014-07-05)
Chung, Chen-Chen
;
Binh Tinh Tran
;
Lin, Kung-Liang
;
Ho, Yen-Teng
;
Yu, Hung-Wei
In this paper, a zinc oxide (ZnO) nanotube, fabricated by the hydrothermal growth method on triple-junction (T-J) solar cell devices to enhance efficiency, is investigated. Compared to those of bare T-J solar cells (without antireflection (AR) coating) and solar cells with Si3N4 AR coatings, the experimental results show that the T-J solar cells, which use a ZnO nanotube as an AR coating, have the lowest reflectance in the short wavelength spectrum. The ZnO nanotube has the lowest light reflection among all experimental samples, especially in the range of 350 to 500 nm from ultraviolet (UV) to visible light. It was found that a ZnO nanotube can enhance the conversion efficiency by 4.9%, compared with a conventional T-J solar cell. The Si3N4 AR coatings also enhance the conversion efficiency by 3.2%.The results show that a cell with ZnO nanotube coating could greatly improve solar cell performances.
The Circle-grid Electrode on Concentrated GaAs Solar Cells Efficiency
(2011)
Chung, Chen-Chen
;
Yu, Hung-Wei
;
Hsu, Li-Han
;
Kuo, Chien-I
;
Nguyen-Hong Quan
The relationship between front contact pattern of GaAs single-junction solar cell with conversion efficiency at different concentration ratios is studied in this paper. Five different front circle-grid patterns were designed and patterned on the in-house fabricated single junction GaAs solar cells. At high light concentration ratio, the cell efficiency is strongly dependent on the series resistance of the electrode. At the same time, the thermal effect should also be taken into consideration, especially when a device is operating under high concentration ratio. Therefore, the aim of this work is to find a suitable front contact pattern for a GaAs single-junction solar cell to increase the conversion efficiency under high concentration solar radiation. It is found that the device with proper pattern design geometrical shadowing factor of 7.1% has the best cell efficiency of 27.05% at CR>100x, AM1.5G.