Effect of temperature on GaAs/AlGaAs multiple quantum well solar cells

Al0.36Ga0.64As p-i-n solar cells with multiple quantum wells (MQW) GaAs/Al0.36Ga0.64As in the i-region have been tested at various temperatures, ranging from −10 to 100°C, and compared with conventional solar cells composed of either the quantum well material (GaAs) or the barrier material (Al0.36Ga0.64As) alone. The dark current of the MQW cells lied between the dark currents of the conventional cells. The increase of dark current with temperature was accompanied by a small reduction of the diode ideality factor and the main component of the dark current was found to be dominated by recombination/generation processes. When the cells were illuminated with a halogen lamp of 198 mW cm−2 intensity, the open-circuit voltage Voc of the MQW cells was above the Voc of the conventional cell consisting of the well material alone. The dependence of the number of wells in the i-region on the output performance of the MQW cells was found to be more profound at low temperatures than at high temperatures. All MQW cells examined in this work showed remarkable output performance with temperature. It has been clearly indicated, for the first time, that GaAs/Al0.36Ga0.64As MQW structures, when fully processed as solar cells, can deliver more output power under intense illumination than conventional solar cells composed of the well material alone.