Photovoltaic properties of a single layer poly [3-(4-octylphenyl)-2,2′-bithiophene] (PTOPT)

A Schottky contact is made from a single layer polymer poly [3-(4-octylphenyl)-2,2′-bithiophene] (PTOPT) in its neutral state and a low work function metal (Al). The electrical and optical properties have been investigated by means of I–V measurements in the dark and under illumination. Various parameters such as the reverse saturation current density, barrier height, and diode quality factor were determined from the I–V curves in the dark of Al/PTOPT/ITO sandwich structure using thermionic emission theory. Spectral response of the device was measured at various wavelengths giving a peak at 500 nm. The IPCE% was obtained for illumination through both the Al and ITO sides. By illuminating the diode with a monochromatic light of wavelength 500 nm, the open-circuit voltage, short-circuit current density, power conversion efficiency, and fill-factor (FF) were obtained. The dependence of photocurrent on light intensity was also recorded and analyzed.