Voltage recovery in charged InAs/GaAs quantum dot solar cells

The realization of high efficiency quantum dot intermediate band solar cells is challenging due to the thermally activated charge escaping at high temperatures. The enhancement in short circuit current of quantum dot solar cells is largely undermined by the voltage loss. In this paper, InAs/GaAs quantum dot solar cells with direct Si doping in the quantum dots are studied. The open circuit voltage is improved with increasing doping concentration in the quantum dots. The recovery of open circuit voltage as large as 105mV is measured. This voltage recovery is attributed to suppressed charge thermal escaping from quantum dots. The suppressed thermal coupling is supported by the external quantum efficiency and photoluminescence measurements.