Effect of bandgap variation on photovoltaic properties of lead sulfide quantum dot solar cell

The tunable bandgap of quantum dot (QD)-based solar cells is their greatest advantage, providing control over light absorption region. However, the investigation of the effect of bandgap variation on QD-based photovoltaic properties is insufficient, in contrast to well-defined material properties. In this study, we analyze the electrical properties of solar cells fabricated with bandgap-tuned lead sulfide (PbS) QDs to examine the effect of bandgap variation on photovoltaic properties. We find that reducing the thickness of the QD active layer is necessary to achieve high power conversion efficiency mainly because the doping concentration of the QD film increases as the QD bandgap decreases. We suggest that QD photovoltaic device structures should be designed with consideration of their electrical characteristics in relation to the bandgap.