Charge transport FET device applications

FET applications of thiophene-based materials have a two-decade history. Pioneering work was conducted by Koezuka and co-workers [33], The device utilized electrochemically synthesized polythiophene as the channel layer, its mobility being 10 cm V s . This work was followed by Garnier and co-workers [13], who used sexithiophene as the channel layer and recorded an enhanced mobility of 10 cm s . Akimichi et al. [14] made FET devices using alkyl-capped oligothiophenes and mentioned that the alkyl substitution not only improves the chemical stability of the oligothiophenes but also enhances the mobility. A similar substitution effect was also observed with other oligomers [34, 35]. 

More recently even higher mobilities were recorded with single crystals of rubrene [39, 40]. An upper limit of the mobility has to be pursued and determined with various organic materials having different morphologies, typically single crystals and thin films. 

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