Electron transfer via organic dyes for solar conversion

The dye-sensitized solar cells are formed by a wide band gap semiconductor such as TiO2, an organic dye coated on the semiconductor for light absorpti on, an electrolyte containing a suitable redox couple and a counterelectrod e. In the present study, we investigated the functioning of black berry ext ract to sensitize TiO2 for light absorption. TiO2 thick films were screen-p rinted and sintered at 450 degrees C in air. It was sensitized with a fruit extract that contains anthocynin kind of organic dye, for example black be rry extract. The black berry extract sensitized TiO2 exhibited an increase in the photocurrent response indicating excess generation of photoelectrons due to light absorption by black berry extract. The photocurrent response in this case depends on parameters such as soaking time of TiO2 in black be rry juice, period of illumination, etc. The black berry extract was analyze d by optical absorption spectroscopy to characterize its absorption band. A n absorption peak was observed at 517 nm, the intensity of which depends on the concentration of the black berry extract. (C) 1999 Elsevier Science B. V. All rights reserved.