Novel stable (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo1,2-b:4,5-b′difuran-2,6(3H,7H)-dione based donor–acceptor polymer semiconductors for n-type organic thin film transistors

(3E,7E)-3,7-Bis(2-oxoindolin-3-ylidene)benzo1,2-b:4,5-b'difuran-2,6(3H,7H)-dione (IBDF) was used as a new electron-acceptor building block for polymer semiconductors with very low-lying energy levels. A copolymer of IBDF and thiophene showed stable electron transport performance in thin film transistors.