Efficient Quantum Dot Solar Cells with Sustainable Oxide Thin Films

Thin-film solar cells are more promising for low-cost and large-area photovoltaic devices. Tremendous efforts have been invested in using cadmium telluride (CdTe), copper indium gallium selenide (CIGS), and perovskite thin films for energy harvesting. In contrast, zinc oxide (ZnO) and molybdenum trioxides (MoO3) are relatively earth-abundant, environmentally stable, and sustainable for thin-film solar cells. ZnO nanostructures have recently gained success in producing effective (similar to 8.55%) quantum dot solar cells (QDSCs). While nanostructures offer high surface areas to receive electrons from quantum dots (QDs), they are dominated by surface dangling bonds. These defects can trap electrons and limit effective transport at the interface between the ZnO nanostructures and QDs. We anticipate that QDSCs based on thin-film materials can minimize such interface trapping states and be more efficient than those demonstrated with ZnO nanostructures. We strategically develop quality ZnO and MoO3 thin films to produce QDSCs with power conversion efficiency as high as 11.4%. Our approach will inspire others to use scalable thin-film technology and QDs for solar energy harvesting based on sustainable ZnO and MoO3.