Effect of temperature on the performance of CuPc/C₆₀photovoltaic device

Abstract

We demonstrate the effect of temperature on the performance of a copper phthalocyanine (CuPc)/fullerene (C60) based bilayer organic photovoltaic device. The current–voltage (J–V) characteristics of the device have been studied in the dark as well as under illumination at different temperatures in the range 300–125 K. The variation in temperature strongly influences the device parameters and hence its performance. It has been found that (i) the lowering of the temperature results in a reduction in the rectification ratio, (ii) reverse bias current at low temperatures is governed by the tunnelling of the charge carriers and (iii) short circuit current (Jsc) decreases while the open circuit voltage (Voc) increases with the decrease in temperature. The change in Voc with temperature has been attributed to the variation in the built-in voltage (Vbi) arising due to band bending with a decrease in temperature. In summary the overall efficiency of the device first increases and then decreases with the reduction in temperature.