A Non‐Halogenated Polymer Donor Based on Imide Unit for Organic Solar Cells with Efficiency Nearly 16%

Comprehensive Summary Non‐halogenated polymers have great potential in the commercialization of organic solar cells (OSCs) due to their advantages in the manufacturing process. However, high‐performance donor polymers are limited to a small amount of building blocks. Herein, we utilize as building block 4 H ‐dithieno[3,2‐ e :2',3'‐ g ]isoindole‐4,6(5 H )‐dione (DTID) to design and synthesize a relevant non‐halogenated polymer PBTID for active layers in OSCs. PBTID exhibits a strong absorption in the wavelength range of 400—600 nm with a distinctly wide optical bandgap of 2.06 eV, a low‐lying highest occupied molecular orbital (HOMO) energy level of −5.53 eV. In addition, this polymer has a very strong aggregation effect in solution and could form nanoscale fibrils in the neat film. Consequently, when blended with the non‐fullerene acceptor Y6, the devices achieve a prominent PCE of 15.8% with a high V oc of 0.87 V. The V oc and PCE values are one of the highest values in the non‐halogenated polymer donor‐based OSCs reported to date.