Synthetic strategy for thienothiophene-benzotriazole-based polymers with high backbone planarity and solubility for field-effect transistor applications

We report on a synthetic strategy for a series of thienothiophene-benzotriazole-based polymers-octyl-PTTBTz-F, Si-PTTBTz, and Si-PTTBTz-F-wherein conformational locks are introduced to induce intra- and intermolecular interactions (F center dot center dot center dot S, F center dot center dot center dot H-C, and C-F center dot center dot center dot pi(F)) for high backbone planarity and siloxane-terminated side chains are introduced to increase solubility. The three polymers were utilized as active layers in organic field-effect transistors, and the effects of thermal annealing on the polymer crystallinity and device performances were studied. Although the fluorine-atom-substituted octyl-PTTBTz-F showed a moderate hole mobility of up to 4.2 x 10(-3) cm(2) V-1 s(-1) with enhanced molecular orientation because of conformational locks, it had poor solubility in common organic solvents. The Si-PTTBTz polymer with the siloxane-terminated side chains showed good solubility but inferior device performance with a hole mobility of up to 2.2 x 10(-4) cm(2) V-1 s(-1). The rationally designed Si-PTIBTz-F polymer, which contains both fluorine atoms in the backbone and siloxane-terminated groups in the side chains, showed an excellent hole mobility of up to 0.11 cm(2) V-1 s(-1) and good solubility in common organic solvents. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.