Temperature effect on the performance of phthalocyanine based photovoltaic devices

Abstract

In this paper, the effect of temperature on performance of phthalocyanine based photovoltaic devices is investigated. Zinc phthalocyanine (ZnPc) and metal free phthalocyanine (H₂Pc) are used as donor whereas fullerene (C₆₀) is used as an acceptor. Prior to these investigations, the thicknesses of the active layers are optimized to get the optimum performance. The optimised device has an efficiency of ~1.4% for ZnPc and ~0.5% for H₂Pc at room temperature. Investigations on the optimized device show that temperature has significant effect on the photovoltaic performance. Short circuit current density (<i style="">J_sc</i>) and fill factor (<i style="">FF</i>) decrease whereas open circuit voltage (<i style="">V_oc</i>) increases with reduction in temperature. The reduction in <i style="">J_sc</i> has been attributed to the temperature dependent electronic properties of the active organic layers while the increment in the <i style="">V_oc</i> has been attributed to the reduction in band bending and increment in built in voltage (<i style="">V_bi</i>) on lowering of temperature. In overall the efficiency first increases and then decreases with reduction in temperature.