A Versatile Planar Building Block with C2V Symmetry for High‐Performance Non‐Halogenated Solvent Processable Polymer Donors.

Planar building block B2TCl with C2V symmetry configuration is designed to prepare polymer donors (PB2TCl‐o and PB2TCl‐i) with good solubility in non‐halogenated solvents. When blended with BTP‐ec9‐4F, PB2TCl‐o‐based devices processed by 1,2‐dimethylbenzene (o‐DMB) give a power conversion efficiency (PCE) of 15.10% with a Voc of 0.89 V, a Jsc of 24.37 mA cm–2, and an fill factor of 69.69%. Semitransparent OSCs based on PB2TCl‐o:BTP‐ec9‐4 can afford a PCE of 9.09% with an average visible transmittance (AVT) of 23.9% and an AT of 24.2%. B2TCl‐o is also used as a third component to prepare random terpolymers PW1 and PW2. Using o‐DMB as the processing solvent, PW1 and PW2‐based devices give improved PCEs of 16.26% and 17.19%, respectively, which are much higher than the parent polymers (PM6 and D18). This work provides a versatile building block B2TCl‐o for the preparation of non‐halogen solvent processable high‐performance polymer donor materials. [ABSTRACT FROM AUTHOR]