Alkynyl-Functionalized Pyrene-Cored Perylene Diimide Electron Acceptors for Efficient Nonfullerene Organic Solar Cells

Integrating two or more perylene diimide (PDI) monomers through the single bond or ring fusion forming a star-shaped structure is a useful strategy for designing high-efficiency electron acceptors. Herein, we implemented an effectual acetylene-linked method of constructing star-shaped PDI-derivative-based high-efficiency nonfullerene organic solar cells (OSCs). A rigid and conjugated pyrene-cored PDI acceptor, B-4TPDI, has been designed and synthesized. The new acceptor manifests a favorable morphology, effective π-electron delocalization, and complementary absorption when it is paired with the polymer donors PTB7-Th or PBDB-T. It is shown that OSCs based on the PTB7-Th:B-4TPDI blend film achieved a power conversion efficiency (PCE) of 7.71% and an outstanding J sc of 18.13 mA cm –2 . More importantly, after adding a small amount of B-4TPDI into the PTB7-Th:ITIC and PBDB-T:ITIC system, the formed ternary OSCs obtained an optimized PCE of 8.76% and 10.93%, respectively. Our work confirms that acetylene linkage would be a prospective π-spacer for designing conjugated PDI-derivative-based new and excellent nonfullerene acceptors.