Influence of oxygen doping on the electrical and photovoltaic properties of Schottky type solar cells based on α-nickel phthalocyanine

Single layer thin film cells were fabricated by successive thermal sublimation of gold, nickel phthalocyanine and lead under high vacuum conditions (10-4 Pa). Structural properties of NiPc film were studied using X-ray diffraction measurements. Charge carrier transport mechanisms were identified from the dark current density-voltage (J-V) characteristics. A rectifying junction was found to exist at the NiPc/Pb interface. The potential barrier height was evaluated under high vacuum and upon exposure of the cells to dry air for different periods of time. Density of acceptors was calculated for O2 doped cells utilising the small a.c. signal capacitance-voltage technique. A photovoltaic effect was observed upon illumination of the sample with white light. Various photovoltaic parameters were determined from the J-V characteristics of the cells as a function of incident light intensity and exposure time to dry air. Although the initial power conversion efficiency (under vacuum) was low the cells show promising photovoltaic characteristics upon doping with O2. © 2003 Elsevier Science B.V. All rights reserved