Roll-to-Roll Printed Large-Area All-Polymer Solar Cells with 5% Efficiency Based on a Low Crystallinity Conjugated Polymer Blend

The challenge of continuous printing in high-efficiency large-area organic solar cells is a key limiting factor for their widespread adoption. A materials design concept for achieving large-area, solution-coated all-polymer bulk heterojunction solar cells with stable phase separation morphology between the donor and acceptor is presented. The key concept lies in inhibiting strong crystallization of donor and acceptor polymers, thus forming intermixed, low crystallinity, and mostly amorphous blends. Based on experiments using donors and acceptors with different degree of crystallinity, the results show that microphase separated donor and acceptor domain sizes are inversely proportional to the crystallinity of the conjugated polymers. This methodology of using low crystallinity donors and acceptors has the added benefit of forming a consistent and robust morphology that is insensitive to different processing conditions, allowing one to easily scale up the printing process from a small-scale solution shearing coater to a large-scale continuous roll-to-roll (R2R) printer. Large-area all-polymer solar cells are continuously roll-toroll slot die printed with power conversion efficiencies of 5%, with combined cell area up to 10 cm(2). This is among the highest efficiencies realized with R2R-coated active layer organic materials on flexible substrate.Bridging Research Interactions through the collaborative Development Grants in Energy (BRIDGE) program under the SunShot initiative of the Department of Energy program [DE-FOA-0000654-1588]; Office of Naval Research [N00014-14-1-0142]; Department of Defense (DoD) through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program; National Science Foundation Materials Genome Program [1434799]; National Research Fund of Luxembourg [6932623]; Swiss National Science Foundation under the Early Mobility Postdoc Project [P2ELP2_155355]; Department of Energy Basic Science (USA) [DE-SC0016523]; National Natural Science Foundation of China [21674001, 51473003]; Hong Kong Innovation and Technology Commission [ITC-CNERC14SC01]; U.S. Department of Energy, Office of Basic Energy Sciences [DE-AC02-76SF00515]; Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]SCI(E)ARTICLE14