Photovoltaic properties of Schottky device based on dye sensitized poly (3-phenyl azo methine thiophene) thin film

The electrical and photovoltaic characteristics of spin coated thin films of poly (3-phenyl azo methine thiophene) (PPAT), sensitized with pyronine (G) (PYR) dye sandwiched between indium tin oxide (ITO) and aluminum (Al) have been investigated. The p-type conductivity and rectification ratio of PPAT increases with dye sensitization. The depletion layer width (9) of about 64 nm evaluated from the C-V measurement reveals the high probability of charge conduction. From J-V characteristics and impedance spectroscopy, it is evidenced that the PYR-PPAT layer form the blocking contact with Al and Ohmic contact with ITO. Also, the device can be modeled by two simple equivalent circuit of resistance-capacitance (RC) elements in series, representing the bulk and a junction region. An increase in conversion efficiency of PPAT is observed from 0.35 to 0.74 after sensitization with PYR under white light illumination. A model based on simple assumptions is used to explain the photoaction spectra of the device. The dye sensitization also causes a reduction in the trapping centers of the material. (C) 2004 Elsevier B.V. All rights reserved.