Large-Area Organic Solar Cells: Material Requirements, Modular Designs, and Printing Methods.

The printing of large-area organic solar cells (OSCs) has become a frontier for organic electronics and is also regarded as a critical step in their industrial applications. With the rapid progress in the field of OSCs, the highest power conversion efficiency (PCE) for small-area devices is approaching 15%, whereas the PCE for large-area devices has also surpassed 10% in a single cell with an area of ≈1 cm2 . Here, the progress of this fast developing area is reviewed, mainly focusing on: 1) material requirements (materials that are able to form efficient thick active layer films for large-area printing); 2) modular designs (effective designs that can suppress electrical, geometric, optical, and additional losses, leading to a reduction in the PCE of the devices, as a consequence of substrate area expansion); and 3) printing methods (various scalable fabrication techniques that are employed for large-area fabrication, including knife coating, slot-die coating, screen printing, inkjet printing, gravure printing, flexographic printing, pad printing, and brush coating). By combining thick-film material systems with efficient modular designs exhibiting low-efficiency losses and employing the right printing methods, the fabrication of large-area OSCs will be successfully realized in the near future.