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 (W) 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.