Perylene diimides functionalized with N-thiadiazole substituents: Synthesis and electronic properties in OFET devices

Two new perylene diimide derivatives N,N'-bis(5-tridecyl-1,3,4-thiadiazol-2-yl) perylene-3,4,9,10-tetracarboxylic 3,4:9,10-diimide (PDI-T1) and N, N'-bis[5-(1-hexyl) nonyl-1,3,4-thiadiazol-2-yl] perylene-3,4,9,10-tetracarboxylic 3,4:9,10-diimide (PDI-T2), achieved by functionalizing the basic perylene molecular core at imide nitrogen with 1,3,4-thiadiazole rings, have been synthesized. Both these compounds make possible the fabrication of n-type organic thin-film transistors able to work in air, even when bare SiO2 surfaces are utilized as gate dielectric. As active channels of transistors in the bottom-contact bottom-gate configuration, PDI-T1 evaporated films exhibited a maximum mobility of 0.016 cm(2)/V s in vacuum. For evaporated PDI-T2 films, instead, mobility values were found to be more than one order of magnitude lower, because of their reduced degree of crystalline order. However, PDI-T2 films can be also deposited by solution techniques and field-effect transistors were fabricated by spin-coating, displaying mobility values ranging between 10(-6) and 10(-5) cm(2)/V s. Similar to what previously found for other perylene diimide derivatives, our experimental work also demonstrates that the electrical response of both PDI-T1 and PDI-T2 transistors under ambient conditions can be improved by increasing the level of hydrophobicity of the dielectric surface. (c) 2012 Elsevier B.V. All rights reserved.