Balanced Ambipolar Organic Thin-Film Transistors Operated under Ambient Conditions: Role of the Donor Moiety in BDOPV-Based Conjugated Copolymers

Organic field-effect transistors (OFETs) are receiving an increased amount of attention because of their intriguing advantages such as flexibility, low cost, and solution processability. Development of organic conjugated polymers with balanced ambipolar carrier transportation operated under ambient conditions, in particular, is considered to be one of the central issues in OFETs. In this work, the 3,7-bis[(E)-2-oxoindolin-3-ylidene]-3,7-dihydrobenzo[1,2-b:4,5-b']difuran-2,6-dione (BDOPV) unit as a good acceptor unit was copolymerized with three donor moieties, thieno[3,2-b]thiophene (TT), benzo[1,2-b:4,5-b']dithiophene (BDT), and benzo[1,2-b:4,5-b']diselenophene (BDSe), to construct three donor-acceptor (D-A) conjugated polymers, BDOPV-TT, BDOPV-BDT, and BDOPV-BDSe. Photophysical and electrochemical properties of all the polymers were characterized. The fabrication of OFETs using three polymers as the active layers demonstrated that all the three polymers showed balanced ambipolar transport properties tested under ambient conditions, which is of great importance in complementary circuits. In particular, both electron and hole mobilities of BDOPV-TT were achieved above 1 cm(2) V-1 s(-1) under ambient conditions (1.37 and 1.70 cm(2) V-1 s(-1), respectively), showing great potential in balanced ambipolar OFETs.