Nonchlorinated Solubility Enhanced by Lipophilicity: An Effective Strategy for Environmentally Benign Processing of Rigidly Regular n‐type Polymeric Semiconductors

Application of high-performance unipolar n-type polymeric semiconductors lagged behind due to those polymers’ poor solubility in green solvents. Traditional methods, such as random copolymerization and asymmetric structuring, enhance solubility but reduce mobility. Here, a universal “lipophilicity strategy” for eco-friendly processing is reported. This strategy could effectively improve the solubility of polymers without sacrificing crystallinity thus maintaining good mobility of the devices. CF3 group and SCF3 group, which are famous for their high lipophilicity, are introduced to (E)-1,2-di(thiophen-2-yl)ethane (TVT). The solubility of two monomers is confirmed to be 5 and 16 times higher than the brominated counterpart, respectively. Moreover, CF3TVT and SCF3TVT not only improve solubility of the polymers but also reduce energy levels of donor unit due to their strong electron withdrawing property. By using Ozawa's condition, three unipolar n-type semiconducting polymers are obtained through direct (hetero)arylation polycondensation (DHAP). Among them, CF3TVT based P2 processed by xylene solutions exhibited the best unipolar n-type mobility up to 1.37 cm2 V−1 s−1 and reached current on/off ratio of 108, for the first time realizing both green synthesis and nonchlorinated processing. In general, this lipophilicity strategy provides an effective guideline to design high-performance n-type polymer with good solubility in nonchlorinated solvents.