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Ternary chalcogenide-based photoelectrochemical cells V. Surface analyses of the CuInX/sub 2//aqueous polysulfide interface (X = S, Se) by X-Ray photoelectron spectroscopy; absence of Se/S exchange in the CuInSe/sub 2//S /SUB n/ = system

Journal Article · · J. Electrochem. Soc.; (United States)
DOI:https://doi.org/10.1149/1.2114017· OSTI ID:5347714

n-CuInS/sub 2/ and n-CuInSe/sub 2/ were subjected to surface analyses by x-ray photoelectron and Auger electron spectroscopy, after their use as photoanodes in polysulfide solutions. For CuInS/sub 2/ samples that had a poor (ca. 2%) conversion efficiency, a rather heterogeneous surface was found, with patches rich in In, which is probably present mainly as oxide. Some CuO was found as well, although the top layer was depleted in Cu, compared to a reference sample. More efficient (ca. 5%) samples showed a more homogeneous surface and even stronger Cu depletion. These changes are ascribed to additional surface treatments, viz., dipping in hot KCN solution and thermal oxidation o the resultant etched surface. For CuInSe/sub 2/ samples, no significant exchange of lattice Se by S from the polysulfide solution is seen, in sharp contrast to what is observed for CdSe or CdIn/sub 2/Se/sub 4/. If sulfur is found, its presence could be correlated with the spurious occurrence of Cd (used as dopant) or Ag (used for the ohmic back contact). Cu depletion also occur near the surface of the diselenide after use in polysulfide solution. Most of the remaining In seems to occur in indiu oxide and/or indium selenide. Cu/sub 2/ was found neither here nor on the surface of the more efficient disulfide sample. It is suggested that the occurrence of an indium oxide top layer, aided by thermal oxidation of the electrode in the case o CuInSe/sub 2/, has a beneficial effect on electrode performance.

Research Organization:
The Weizmann Institute of Science, Rehovot
OSTI ID:
5347714
Journal Information:
J. Electrochem. Soc.; (United States), Journal Name: J. Electrochem. Soc.; (United States) Vol. 132:5; ISSN JESOA
Country of Publication:
United States
Language:
English