Fabrication of highly-transparent solar cell in centimeter scale based on atomically thin 2D materials

Transition metal dichalcogenides (TMD) is one of the most attractive materials for future transparent and flexible optoelectrical devices due to their atomically thin structure, band gap in visible light range, and high optical transparency. Recently, we have developed a new Schottky type TMD-based solar cell, which can be simply formed by asymmetrically contacting electrodes and TMD. The power conversion efficiency (PCE) can be reached up to 0.7 %, which is the highest value for solar cell with similar TMD thickness [1]. To make highly-transparent solar cell with this Schottky type structure, plasma sputtered indium tin oxide (ITO) electrodes are used in this study. By coating various thin metals on top of ITO (M_x/ITO) and inserting a thin layer of WO₃, Schottky barrier height can be well controlled between electrode and TMD. Then, the PCE of our solar cell with the optimized electrode (WO₃/M_x/ITO) becomes more than 1000 times higher than that of a device using a normal ITO electrode. Furthermore, a near-invisible (averaged transparency >79%) solar cell in 1 cm² scale has been successfully fabricated. These findings can contribute to the study of TMD-based transparent solar cell from fundamentals to truly industrialized stages.