Current transport mechanisms and photovoltaic properties of tetraphenylporphyrin/n-type silicon heterojunction solar cell

Abstract Au/tetraphenylporphyrin (TPP)/n-type silicon (n-Si)/Al heterojunction solar cell was constructed and prepared by growing TPP film on n-Si wafer using thermal evaporation technique, the dark current–voltage and dark capacitance–voltage characteristics of the cell were measured over temperature range from 291 to 373 K. The parameters and mechanisms of conduction of heterojunction diode have been studied, current–voltage characteristics indicated an ohmic conduction at voltages 1.3 V. Space charge-limited conduction and multi-step tunneling mechanisms occur consequentially at (0.11–1.25) V. The capacitance–voltage measurements showed that the diode is linearly graded junction and the width of depletion layer, impurity gradient and built in voltage were estimated. The current–voltage characteristics under illumination have also been investigated and photovoltaic properties of Au/TPP/n-Si/Al solar cell were evaluated.