Perfluoroalkyl-Functionalized Thiazole–ThiopheneOligomers as N-Channel Semiconductors in Organic Field-Effectand Light-Emitting Transistors.

Despite their favorable electronicand structural properties, thesynthetic development and incorporation of thiazole-based buildingblocks into n-type semiconductors has lagged behindthat of other π-deficient building blocks. Since thiazole insertioninto π-conjugated systems is synthetically more demanding, continuousresearch efforts are essential to underscore their properties in electron-transportingdevices. Here, we report the design, synthesis, and characterizationof a new series of thiazole–thiophene tetra- (1and 2) and hexa-heteroaryl (3and 4) co-oligomers, varied by core extension and regiochemistry,which are end-functionalized with electron-withdrawing perfluorohexylsubstituents. These new semiconductors are found to exhibit excellent n-channel OFET transport with electron mobilities (μe) as high as 1.30 cm2/(V·s)(Ion/Ioff>106) for films of 2deposited at room temperature.In contrary to previous studies, we show here that 2,2′-bithiazolecan be a very practical building block for high-performance n-channel semiconductors. Additionally, upon 2,2′-and 5,5′-bithiazole insertion into a sexithiophene backboneof well-known DFH-6T, significant charge transport improvements(from 0.001–0.021 cm2/(V·s) to 0.20–0.70cm2/(V·s)) were observed for 3and 4. Analysis of the thin-film morphological and microstructuralcharacteristics, in combination with the physicochemical properties,explains the observed high mobilities for the present semiconductors.Finally, we demonstrate for the first time implementation of a thiazolesemiconductor (2) into a trilayer light-emitting transistor(OLET) enabling green light emission. Our results show that thiazoleis a promising building block for efficient electron transport inπ-conjugated semiconductor thin-films, and it should be studiedmore in future optoelectronic applications. [ABSTRACT FROM AUTHOR]