Solution-Processed Short-Wave Infrared PbS Colloidal Quantum Dot/ZnO Nanowire Solar Cells Giving High Open-Circuit Voltage

A systematic investigation into the performance of PbS quantum dot (QD)/ZnO nanowire (NW) solar cells in the near-infrared (NIR) and short-wave infrared (SWIR) regions was carried out. The solar cells were confirmed to convert a wide range of solar energy (3.54–0.62 eV, corresponding to 0.35–2.0 μm). We found that the solar cells working in the SWIR region had a high open-circuit voltage ( V oc ). A relatively high V oc of 0.25 V was achieved even in solar cells whose photocurrent onsets were at approximately 0.64 eV (1.9 μm); this V oc is as high as that of Ge solar cells, which have been used for III–V compound semiconductor triple-junction solar cells. Although short-circuit current density and fill factor have to be further increased, these results indicate that solution-processed colloidal QD solar cells with ZnO NWs are promising candidates for the middle and/or bottom subcells of multijunction solar cells.