A comparative study of the effects of light and heavy alkali-halide postdeposition treatment on CuGaSe2 and Cu(In, Ga)Se2 thin-film solar cells. (15th November 2020)

• Record Type: Journal Article
• Authors: Ishizuka, Shogo; Taguchi, Noboru; Nishinaga, Jiro; Kamikawa, Yukiko; Shibata, Hajime
• Is Part Of: Solar energy. Volume 211(2020)
• Page Start: 1092
• Page End: 1101
• Publication Date: 2020-11-15
• Subjects: CuGaSe2 -- Cu(In, Ga)Se2 -- Lithium -- Cesium -- Interfaces; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2020.10.048
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: Beneficial effects of heavy alkali-metals on CuGaSe2 films and devices are small. LiF postdeposition treatment leads to few CuGaSe2 film surface modifications. Li may be more beneficial than Cs for CuGaSe2 devices, unlike quaternary Cu(In, Ga)Se2 . Abstract: Enhancement of photovoltaic performance due to alkali-metal doping in various thin-film compound solar cells such as chalcogenide Cu(In, Ga)Se2 (CIGS), Cu2 ZnSnS4 (CZTS), and organic–inorganic hybrid perovskite, is significant in the development of photovoltaic technologies. In this work, the effects of light Li- and heavy Cs-doping in ternary CuGaSe2 (CGS) and quaternary CIGS thin-films and devices are compared. The new findings are: (i) heavy alkali-metal halide CsF postdeposition treatment (PDT) modifies the CGS film surface morphology and increases the carrier density; however, the beneficial effects of Cs on the CGS photovoltaic performance are low when compared to the results observed from quaternary CIGS devices; (ii) LiF-PDT leads to no significant CGS and CIGS film surface (hetero p-n junction interface) modifications; thus, the use of a thin (approximately 30 nm) CdS buffer layer is not effective in enhancing photovoltaic performance; and (iii) the beneficial effects of either light Li or heavy Cs on ternary CGS devices are modest; nonetheless, Li may be more effective than Cs, unlike quaternary CIGS devices.