Exceptional stability of Mg-implemented PbS quantum dot solar cells realized by galvanic corrosion protection

Lead sulfide (PbS) quantum dots (QDs) have been the focus of photovoltaics research because of their high quantum confinement effect and broad band absorption in the red to near-infrared (NIR) region. However, PbS QDs are easily oxidized under ambient conditions and many research groups are trying to improve their stability in air. In particular, various organic or inorganic materials are used to protect the PbS surface. In this report, we introduce the Mg-implemented PbS colloidal system (Mg-PbS) with enhanced PbS air stability. We obtained a short-circuit current density (J_SC) of 11.8 mA cm^-2, open-circuit voltage (V_OC) of 0.6 V, fill factor (FF) of 62.3%, and power conversion efficiency (η) of 4.4% in a m-TiO₂ solid PV cell using Mg-PbS. In addition, their cell properties remained unchanged in a corrosive ethanedithiol solution even after 4 days because of the Mg galvanic corrosion protection of PbS QDs, whereas the PbS QD solar cells were quickly degraded by the corrosion of PbS QDs.