Control of Ambipolar Charge Transport by Changing Fluorine Substitution Position in Isoindigo-based Conjugated Polymers for High Performance Organic Field-Effect Transistors
발표자
()
초록
내용
We report a new molecular design to achieve highly balanced charge transport for donor-acceptor (D-A) copolymer through fluorine substitution on bithiophene (T2). To study the effects of fluorine substitution site on structural and electronic property, we synthesize two IIG-based copolymers (PIIG-iFT2 and PIIG-oFT2), which contain two fluorine atoms at the T2 inner and outer site. Fluorination at the outer site of T2 in PIIG-oFT2 polymer effectively lowered molecular energy levels and increased molecular planarity more than fluorination at the inner site of T2. PIIG-oFT2 organic field-effect transistors exhibited highly balanced mobility, hole mobility (uh)/electron mobility (ue) = 1 by increasing electron mobility whereas PIIG-T2 (uh/ue = 9.0) and PIIG-iFT2 (uh/ue = 2.4) exhibited unbalanced transport. The ambipolar complementary-like inverter was also fabricated by simple one time coating of PIIG-oFT2 with gain = 21.