Abstract
Energy shortage has become one of the important issues to be resolved. People are eagerly looking for alternative energy sources to replace traditional fossil fuels. Organic solar cells have attracted much attention due to their unique properties such as low-cost, simple fabrication process and flexibility. In addition, it can be combined with roll-to-roll process to fabricate large-area organic solar cell. Most of the organic solar cells are fabricated using spin-coating technique; however, this technique is not applicable for large-area device fabrication. Therefore, we develop blade-coating process to fabricate large-area organic solar cells, not only enhancing the efficiency of material usage but also developing toward roll-to-roll process in the future. In this work, the hole transport layer and active layer are deposited by blade-coating method. The active layer was a bulk heterojunction (BHJ) consisting of P3HT and PCBM. However, the uniformity of large-area blade-coating will be affected by several factors such as the flow variability, surface tension of the solution and the velocity of blading. We discuss the different heating methods and use low boiling point CB to replace DCB as the solvent of active layer. To develop the serial connection of large-area devices, the scaling effect of the fabricated devices is studied by varying the widths of active area while keeping lengths the same. As a result, with increasing the width of active area, the impact of series resistance is more significant but the aperture ratio is increased. Therefore, an optimal width of the active area could be obtained, showing a good agreement with the simulated results of organic large-area solar cell. Therefore, we expect the series of large-area solar cells could be a good reference for the future.