Dithienosilole- and dibenzosilole-thiophene copolymers as semiconductors for organic thin-film transistors

The synthesis and physicochemical properties of a new class of thiophene/arenesilole-containing pi-conjugated polymers are reported. Examples of this new polymer class include the following: poly(2,5-bis(3',3' '-dihexylsilylene-2',2' '-bithieno)thiophene) (TS6T1), poly(2,5'-bis(3' ',3' ''-dihexylsilylene-2' ',2' ''-bithieno)bithiophene) (TS6T2), poly(2,5'-bis(2' ',2' ''-dioctylsilylene-1' ',1' ''-biphenyl)thiophene) (BS8T1), and poly(2,5'-bis(2' ',2' ''-dioctylsilylene-1' ',1' ''-biphenyl)bithiophene) (BS8T2). Organic field-effect transistors (OFETs) with hole carrier mobilities as high as 0.02-0.06 cm2/V s in air, low turn-on voltages, and current on/off ratios >105-106 are fabricated using solution processing techniques with the above polymers as the active channel layer. OFETs based on this polymer class exhibit excellent ambient operational stability.