Browsing by Author "Jheng, Bao-Tang"

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A non-selenization technology by co-sputtering deposition for solar cell applications
(1970-01-01)
Jheng, Bao-Tang
;
Liu, Po-Tsun
;
Wu, Meng-Chyi
;
Shieh, Han-Ping D.
;
光電工程學系
"This work presents a novel method to form polycrystalline Cu(In1-xGax)Se-2 (CIGS) thin film by co-sputtering of In-Se and Cu-Ga alloy targets without an additional selenization process. An attempt was also made to thoroughly elucidate the surface morphology, crystalline phases, physical properties, and chemical properties of the CIGS films by using material analysis methods. Experimental results indicate that CIGS thin films featured densely packed grains and chalcopyrite phase peaks of (112), (220), (204), (312), and (116). Raman spectroscopy analysis revealed chalcopyrite CIGS phase with Raman shift at 175 cm(-1), while no signal at 258 cm(-1) indicated the exclusion of Cu2-xSe phase. Hall effect measurements confirmed the polycrystalline Cu(In, Ga)Se-2 thin film to be of p type semiconductor with a film resistivity and mobility of 2.19 x 102 Omega cm and 88 cm(2)/V s, respectively. (C) 2012 Optical Society of America"
A promising sputtering route for dense Cu2ZnSnS4 absorber films and their photovoltaic performance
(2014-09-01)
Jheng, Bao-Tang
;
Liu, Po-Tsun
;
Wu, Meng-Chyi
;
光電工程學系
;
顯示科技研究所
Copper zinc tin sulfide (Cu2ZnSnS4, CZTS) is highly abundant in nature. It is an important absorber material for the development of low-cost and sustainable next-generation I-2-II-IV-VI4 thin-film solar cells because it has a the tunable direct band gap energy, inexpensive constituent elements, and a large absorption coefficient in the visible wavelength region. This work develops an efficient one-step vacuum-based approach to depositing CZTS films without the need to supply excess sulfur during/after deposition or to perform any post-sulfurization treatment. This one-step RF sputtering process produces CZTS films that are crystalline, phase-pure, dense, smooth, and continuous. Air Mass 1.5 G power conversion efficiencies of as high as 6% have been achieved with an antireflection coating, demonstrating that this new approach has great potential as a low-cost alternative for high-efficiency CZTS solar cell production. (C) 2014 Elsevier B.V. All rights reserved.
A promising sputtering route for dense Cu2ZnSnS4 absorber films and their photovoltaic performance
(2014-09-01)
Jheng, Bao-Tang
;
Liu, Po-Tsun
;
Wu, Meng-Chyi
;
光電工程學系
;
顯示科技研究所
Copper zinc tin sulfide (Cu2ZnSnS4, CZTS) is highly abundant in nature. It is an important absorber material for the development of low-cost and sustainable next-generation I-2-II-IV-VI4 thin-film solar cells because it has a the tunable direct band gap energy, inexpensive constituent elements, and a large absorption coefficient in the visible wavelength region. This work develops an efficient one-step vacuum-based approach to depositing CZTS films without the need to supply excess sulfur during/after deposition or to perform any post-sulfurization treatment. This one-step RF sputtering process produces CZTS films that are crystalline, phase-pure, dense, smooth, and continuous. Air Mass 1.5 G power conversion efficiencies of as high as 6% have been achieved with an antireflection coating, demonstrating that this new approach has great potential as a low-cost alternative for high-efficiency CZTS solar cell production. (C) 2014 Elsevier B.V. All rights reserved.
Effects of ZnO-nanostructure antireflection coatings on sulfurization-free Cu2ZnSnS4 absorber deposited by single-step co-sputtering process
(2013-07-29)
Jheng, Bao-Tang
;
Liu, Po-Tsun
;
Wang, Min-Chuan
;
Wu, Meng-Chyi
;
電子工程學系及電子研究所
ZnO nanostructures as anti-reflective coatings were synthesized by using hydrothermal technique for a sulfurization-free Cu2ZnSnS4 absorber prepared by co-sputtering deposition. By controlling the morphology of solution-grown ZnO nanostructures, the average reflectance of the Cu2ZnSnS4 solar cell with branched ZnO nanorods decreased from 7.6% to 1.12%, and the energy conversion efficiency promoted by 10.4% from the initial value of 4.8% to 5.3%. The efficiency improvement was well studied with the effects of the gradually increased refractive index between the air and the top electrode of Cu2ZnSnS4 solar device, due to the presence of the ZnO nanostructure. (C) 2013 AIP Publishing LLC.
Efficiency enhancement of non-selenized Cu(In,Ga)Se-2 solar cells employing scalable low-cost antireflective coating
(2014-07-04)
Jheng, Bao-Tang
;
Liu, Po-Tsun
;
Wu, Meng-Chyi
;
光電工程學系
;
顯示科技研究所
In this study, a non-selenized CuInGaSe2 (CIGS) solar device with textured zinc oxide (ZnO) antireflection coatings was studied. The ZnO nanostructure was fabricated by a low-temperature aqueous solution deposition method. With controlling the morphology of the solution-grown tapered ZnO nanorod coatings, the average reflectance of the CIGS solar device decreased from 8.6% to 2.1%, and the energy conversion efficiency increased from 9.1% to 11.1%. The performance improvement in the CuInGaSe2 thin-film solar cell was well explained due to the gradual increase of the refractive index between air and the top electrode of solar cell device by the insertion of the ZnO nanostructure. The results demonstrate a potential application of the ZnO nanostructure array for efficient solar device technology.