Temperature dependences of In_<i>x</i>Ga_1−<i>x</i>N multiple quantum well solar cells

Abstract

In this work, high open circuit voltages (Voc) of In0.2Ga0.8N and In0.28Ga0.72N multiple quantum well solar cells (MQWSCs) are experimentally obtained (2.2 V and 1.8 V, respectively). The Voc of In0.28Ga0.72N MQWSCs is lower than the expected value due to serious indium segregation problems causing more defects in In0.28Ga0.72N films, which is consistent with the observation of a high ideality factor in dark current measurement. The temperature dependence of the Voc and the short circuit current (Jsc) in In0.2Ga0.8N MQWSCs is found to be larger than the corresponding values in In0.28Ga0.72N MQWSCs. It is also observed that higher quantum well energy barrier exhibits a low fill factor of 0.52 due possibly to the loss of electric field and the higher energy barrier. This obtained efficiency increases with temperatures up to 100 °C and then decreases due to competing results between the reduction in Voc and an increase in Jsc.