Light-induced circuit parameter variation in self-assembled quantum-dot photovoltaic cell

Abstract

We investigate the variations of circuit parameters of photovoltaic (PV) cells containing self-assembled InSb and GaSb quantum dots. The solar cell samples are fabricated by conventional molecular beam epitaxy on (001) GaAs substrate. The current–voltage (I-V) characteristics and the frequency response (10 Hz – 100 kHz) of the fabricated cell is then extracted in dark and illuminated environment. The obtained I-V curves show typical PV properties. The static series and shunt resistances can be then extracted from this measurement result. From the Nyquist plot of the device impedance, both dynamic resistance and capacitance can be further extracted. Variations of these values are quantified. Light-induced lowering of the resistance values are explained by the presence of photogenerated carriers. This work provides a useful information for both the basic understanding of PV devices and the design of electronic circuit for energy harvesting and sensing with PV cells.