Sulphidation of electrodeposited cuprous oxide thin films for photovoltaicapplications

Electrodeposited cuprous oxide thin films on indium-doped tin oxide (ITO) s ubstrates were sulphided by exposing them to a spray of aqueous solution of sodium sulphide or to a mixture of hydrogen sulphide and nitrogen gases. B oth methods produced light darker and darker films having different photovo ltaic characteristics in a solar cell structure. The photovoltages produced by the light darker films under AM 1.5 illumination was negative as compar ed to the positive photovoltages produced by the darker films. Spectral res ponse measurements revealed that most of the light darker films produced po sitive photovoltages in the shorter wavelengths and negative photovoltages in the longer wavelengths. However, Some of the light darker films produced only the negative photovoltage for the entire spectral range and their pho tovoltaic properties were comparatively better. Darker films resulted in on ly the positive photovoltages in the entire spectral range. As a result of the sulphidation, the bulk crystal structure of the cuprous oxide thin film s was not changed, however, the interfacial characteristics of the solar ce ll structure were modified. (C) 2000 Elsevier Science B.V. All rights reser ved.