RESUMO
In the development of high-performance organic solar cells (OSCs), the self-organization of organic semiconductors plays a crucial role. This study focuses on the precisely manipulation of molecular assemble via tuning alkyl side-chain topology in a series of low-cost nonfused-ring electron acceptors (NFREAs). Among the three NFREAs investigated, DPA-4, which possesses an asymmetric alkyl side-chain length, exhibits a tight packing in the crystal and high crystallinity in the film, contributing to improved electron mobility and favorable film morphology for DPA-4. As a result, the OSC device based on DPA-4 achieves an excellent power conversion efficiency of 16.67 %, ranking among the highest efficiencies for NFREA-based OSCs.
RESUMO
Achieving high-performance as-cast OSCs is crucial for industrialization in the future, owing to the advantages of better stability, environmental-friendly, and decreasing production cost. In this regard, we synthesized an A-DA'D-A type acceptor, Y6-eC6-BO, by shortening the straight alkyl side-chains on the thiophene position from C11 to C6 as well as lengthening the branched alkyl side-chains on the pyrrole position of Y6 to achieve a stronger crystallization and better miscibility than Y6. As a result, the corresponding chloroform-processed as-cast PM6: Y6-eC6-BO OSC showed a high PCE of 17.33%, which was one of the highest efficiencies of as-cast OSCs. And the as-cast PM6:Y6-eC6-BO OSCs processed from o-xylene displayed a PCE of 16.38%, as far as we know, this is among the highest efficiencies of non-halogenated-solvent processed as-cast OSCs. These results demonstrated tailoring the alkyl side-chain of NFAs is a feasible and simple approach to achieve high performance as-cast OSCs and provides guideline in molecular design in the future.