Dicyanodithioquinoline‐Based Donor Polymers With Large Dipole Moments for Efficient Organic Solar Cells Exceeding 20% Power Conversion Efficiency

Abstract

ABSTRACT Constructing efficient donor polymers is a crucial strategy to break through the bottleneck of organic solar cells (OSCs). Herein, a new acceptor unit dicyanodithioquinoline (TQCN) with large dipole moment (12.90 Debye) was first used to construct high performance polymeric donor PCN7. Theoretical calculations and experimental results confirm that, compared to PM6, the TQCN block suppresses exciton‐vibration coupling through enhanced intermolecular interactions and reduced exciton reorganization energy. The PCN7/L8‐BO binary OSCs yielded a remarkable power conversion efficiency (PCE) of 19.45%, representing one of the highest values among binary OSCs. It exhibits an open‐circuit voltage ( V OC ) of 0.910 V and a non‐radiative recombination energy loss (Δ E 3 ) of 0.216 eV, which are significantly superior to those of the PM6‐based device (0.883 V, 0.252 eV) and the D18‐based device (0.903 V, 0.221 eV). Multiple batches of PCN7 exhibited excellent PCE with good reproducibility. In addition, the D18:PCN7/L8‐BO ternary device exhibits an improved efficiency of 20.06%. These results confirm the potential of the TQCN acceptor block in suppressing exciton‐vibration coupling, providing a viable route toward designing donor materials with both low energy loss ( E loss ) and high PCE.