Diphenyl derivatives of dinaphtho[2,3- b:2′,3′-f]thieno[3,2- b ]thiophene: Organic semiconductors for thermally stable thin-film transistors

Two isomeric diphenyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b] thiophene (DPh-DNTTs), 2,9- and 3,10-DPh-DNTT, were characterized by means of single-crystal X-ray analysis, thin film XRDs, and evaluation of organic field-effect transistors (OFETs) using their evaporated thin films. The packing structures both in the single crystal and thin film state were classified into a typical herringbone packing regardless of the substitution positions, similar to the parent DNTT. The OFETs showed typical p-channel transistor characteristics with mobilities of as high as 3.5 cm² V^-1 s^-1 for both isomers, which is slightly higher than that of the parent DNTT. Compared to related DNTT-based organic semiconductors, a unique point of DPh-DNTTs was found to be superior thermal stability in OFET devices. In particular, the 2,9-DPh-DNTT-based OFETs preserved its superior FET characteristics up to 250 C. For its excellent thermal stability with good FET characteristics, 2,9-DPh-DNTT can be a useful organic semiconductor in various applications that require processes at high temperatures.