Photovoltaic properties of NiPc/p-Si (organic/inorganic) heterojunctions

Current-voltage (I-V) and capacitance-voltage (C-V) characteristics of NiPc thin films deposited on p-Si as heterojunction have been investigated. For I-V measurements, the conventional rectifying properties were shown with rectification ratio of 1750. At low voltages, current in the forward direction was found to obey the diode equation and the conduction was controlled by thermionic emission mechanism. For relatively higher voltages, conduction was dominated by a space-charge-limited conduction mechanism with single trap level of 0.36 eV. On the other hand, the carrier generation-recombination process limits the reverse current. Also, various electrical parameters were determined from the I-V and C-V analysis. The junction exhibits photovoltaic characteristics with open-circuit voltage (Voc) of 0.32 V, a short-circuit current (Isc) of 186 μA and a power conversion efficiency (η) of 1.11%. These parameters have been estimated at room temperature and under illumination of 6 mWcm−2 white light.