Organic thin-film transistors based on bis(1,2,5-thiadiazolo)-p-quinobis (1,3-dithiole)

Organic thin-film transistors (OTFTs) based on the planar stacking sulfur-containing organic compound, bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole) (BTQBT), and grown using the ultrahigh vacuum process of organic molecular-beam deposition have been demonstrated. Effective room-temperature field-effect mobilities as high as (0.044+/-0.006) cm(2)/V s and on/off ratios of 10(3) are achieved. The mobilities depend on the BTQBT growth rate, the gate voltage, and the operating temperature. Coating the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane leads to a three-fold increase in mobility compared with that of an uncoated dielectric. The planar BTQBT molecules form stacks whose axes are normal to the substrate surface. As a result of its unusual crystal structure, the field-effect mobility of BTQBT OTFTs is remarkably high compared with other planar stacking molecules. (C) 2001 American Institute of Physics.