Sensitization of screen-printed and spray-painted TiO2 coatings by chemically deposited CdSe thin films

We have investigated the sensitization of screen-printed and spray-painted titanium dioxide coatings by chemically deposited cadmium selenide thin fil ms. The structural, optical and photoelectrochemical characterization of th e composite films indicate the strong role played by the titanium dioxide m orphology during the sensitization step and during photovoltaic conversion. Air annealing at temperatures close to 400 degreesC helps to improve the p hotocurrent quantum yields and the photostability of the composite coatings in broad pH media. The spectral response, I-V curves and photostability of the sensitized spray-painted and screen-printed TiO2 coatings is superior in polysulfide media than in ferro/ferricyanide electrolytes, indicating th e possibility of electroless etching and/or surface modification by ferricy anide. Overall, the sensitized films based on spray-painted TiO2 show stron ger photocurrents under visible light and withstand better the deleterious effect of the ferro/ferricyanide media. (C) 2001 Elsevier Science B.V. All rights reserved.