Abstract :
Heterojunctions of p-type sodium copper chlorophyllin (p-SCC)/n-type silicon (n-Si) were prepared by deposition of p-SCC film on n-Si wafers using spray-pyrolysis technique. Current–voltage and capacitance–voltage measurements of Au/p-SCC/n-Si/In heterojunctions were performed to discuss the electrical properties of these heterostructures. Rectifying characteristics were observed, which are definitely of the diode type. The current–voltage measurements suggest that the forward current in these junctions involves tunnelling and the results showed that the forward current can be explained by a multi-tunnelling capture–emission model in which the electron emission process dominates the carrier transport mechanism. On the other hand, the reverse current is probably limited by the same conduction process. The capacitance–voltage behavior indicates an abrupt heterojunction model is valid for Au/p-SCC/n-Si/In heterojunctions and the junction parameters such as, built-in potential, VD, carrier concentration, N, the width of depletion layer, W, were obtained. The temperature and frequency dependence of the measured capacitance were also studied. The loaded I–V characteristics under white illumination provided by tungsten lamp (80 mW/cm2) give values of 400 mV, 0.9 mA, 0.38 and 1.7% for the open-circuit voltage, Voc, the short-circuit current, Isc, the fill factor, FF, and conversion efficiency, η, respectively.
