A Medium Bandgap Dimeric Acceptor with High Open-Circuit Voltage for Efficient Organic Solar Cells

Abstract

Dimeric acceptors (DMAs) exhibit significant potential for optimizing both the efficiency and stability of organic solar cells (OSCs). However, medium band-gap DMAs with high open-circuit voltage (Voc) for efficient OSCs remains underexplored. In this study, we designed and synthesized a medium bandgap dimeric acceptor, designated DYO-1, through the strategy of alkoxy side-chain substitutions. The resultant DYO-1 exhibited an upshifted lowest unoccupied molecular orbital (LUMO) level and blue-shifted absorption. Notably, o-xylene (o-XY) processed OSC with PM6:DYO-1 binary blend achieved an ultra-high Voc of 1.022 V and a fill factor (FF) of 73.9%, resulting in a power conversion efficiency (PCE) of 15.1%. To our knowledge, this is the highest PCE reported thus far for dimer-based OSCs with Voc exceeding 1.0 V. Furthermore, DYO-1 was incorporated into PM6:L8-BO-X blend film, effectively reducing excessive aggregation of the host blend film, thus improved the carrier transport efficiency, and enhanced both the short-circuit current (Jsc) and FF. Alongside the improvement in Voc, the PM6:L8-BO-X:DYO-1 based ternary OSC, which is prepared by o-XY solvent, achieved a prominent PCE of 19.6%. Additionally, a module device with an effective area of 13.5 cm2 exhibited a PCE of 15.8%, highlighting the potential for large-area fabrications. Our study unveils the importance of medium bandgap dimeric acceptors in achieving efficient and stable OSCs, providing valuable insights into the design of high-performance electron acceptor.