BIS(DITHIENOTHIOPHENE) ORGANIC FIELD-EFFECT TRANSISTORS WITH A HIGH ON OFF RATIO/

A conjugated, fused-thiophene oligomer, bis(dithienothiophene) (BDT), has been synthesized and deposited by vacuum sublimation as the active layer in organic thin film transistors (TFTs). The TFTs show exceptio nally high ON/OFF ratios up to 10(8) between accumulation and depletio n with sharp turn-on characteristics comparable to that of amorphous s ilicon TFTs (subthreshold slope S=0.6 V/decade). Field-effect mobiliti es are 0.02-0.05 cm(2)/V s. The good performance is explained by the r elatively high pi-pi gap of the short-chain BDT molecule and the favo rable coplanar pi-pi stacking in BDT, differing from the herringbone s tacking in the oligothiophenes. (C) 1997 American Institute of Physics .