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The effects of the immersion into a NH3 aqueous solution on the structural characteristics of the chemically deposited Zn(S,O,OH) layer and photovoltaic performance of the CIGS/Zn(S,O,OH) solar cells were investigated with structural and electrical characterizations. The as-deposited-Zn(S,O,OH) layer possessed a layered structure of upper Zn(OH)2 and Zn(S,O) layers, and the upper Zn(OH)2 layer was removed by the immersion. The conversion efficiency for the CIGS solar cell was improved from 6.8% to 13.7% by removing the upper Zn(OH)2 layer during the immersion. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Cu(In,Ga)Se2 (CIGS) thin films were grown using a rf-cracked Se-radical beam source. A unique combination of film properties, a highly dense and smooth surface with large grain size, is shown. These features seem to have no significant influence on the photovoltaic performance. Defect control in bulk CIGS leading to corresponding variations in the electrical and photoluminescence properties was found to be possible by regulating the Se-radical source parameters. A competitive energy conversion efficiency of 17.5%, comparable to that of a Se-evaporative source grown CIGS device, has been demonstrated from a solar cell fabricated using a Se-radical source grown CIGS absorber. [ABSTRACT FROM AUTHOR]

Abstract: Cu(In,Ga)Se2 (CIGS) thin films were grown by the three-stage process using a rf-plasma cracked Se-radical beam source. CuGaSe2 (CGS) films grown at a maximum substrate temperature of 550°C and CuInSe2 (CIS) and CIGS films grown at the lower temperature of 400°C exhibited highly dense surfaces and large grain size compared with films grown using a conventional Se-evaporative source. This result is attributed to the modification of the growth kinetics due to the presence of active Se-radical species and enhanced surface migration during growth. The effect on CIGS film properties and solar cell performance has been investigated. Enhancements in the cell efficiencies of 400°C-grown CIS and CIGS solar cells have been demonstrated using a Se-radical source. [Copyright &y& Elsevier]

Cu2SnSe3 (CTSe) thin films were prepared by coevaporation at different substrate temperatures (325–400°C). The dependence of the phase transformation of CTSe thin films on the substrate temperature was investigated by X-ray diffraction and transmission electron microscopy analyses. The CTSe films grown at low temperatures (≤350°C) crystallized in the monoclinic phase and showed a strong preferential orientation of the (002) plane. The films grown at higher substrate temperatures (≥375°C) were randomly oriented with a cubic structure. A slight increase in the optical band gap from 0.84eV to 0.91eV was observed as substrate temperature was increased from 325°C to 400°C. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between the composition and conversion efficiency of Cu2ZnSnSe4 (CZTSe)-based solar cells was investigated. CZTSe films were grown by thermal deposition using a coevaporation method. It was found that the composition of CZTSe and Na concentration [Na] have strong correlations to the conversion efficiency, and higher-efficiency samples were obtained with the composition ratios closer to Zn/Sn~1.6, Cu/(Zn+Sn)~0.8, and [Na]~2%. The highest conversion efficiency (η =2.1%) was obtained in the composition region, and the composition was significantly nonstoichiometric. The CZTSe composition was automatically fixed on a tie line between Cu2ZnSnSe4 and ZnSe, and it was demonstrated that this composition can be expressed by one parameter. The structural and electrical properties of the high- and low-efficiency samples were also investigated. No significant differences in such properties were observed between the high- and low-efficiency samples by surface, x-ray diffraction, and Raman measurements. However, the low-efficiency sample showed a high carrier concentration. [Copyright &y& Elsevier]

Abstract: We have developed a fabrication process for integrated submodules using Cu(In,Ga)Se2 (CIGS) absorbers deposited by in-line three-stage evaporation. An in-situ monitoring system for the compositions and thicknesses of the CIGS absorbers was also developed. High-performance CIGS submodules with efficiencies as high as η=15.8% with 17 interconnected cells (aperture area: 76.5cm2) have been fabricated. [ABSTRACT FROM AUTHOR]