Field-effect mobility oligomer

The first soluble oligomer with significant field-effect mobility was 5,5" -dihexyl-quaterthiophene, described by the Gamier group in 1998 [25]. The chemical stracture is shown in Figure 5.3.1. The compound exhibits a mesophase transistion below 100°C. The hexyl chains improve the ordering of the compound relative to unsubstituted quaterthiophene, which in turn is believed to lead to improved mobility as... 

Oligomers based on 4,4-difluorocyclopentadithiophene repeat units exhibit n-type semiconducting behavior [109]. The maximum field effect mobility (0.018 cm V s ) was obtained for a quaterthiophene compound furnished with perfluorohexyl end groups (entry 35, Table 3.1). 

Facchetti and co-workers have synthesized thiophene-diazine co-oligomers 60 and 61 [125]. These materials are much more easily reduced and difficult to oxidize than the corresponding oligothiophenes. However, these systems exhibit relatively low hole field effect mobilities of 10 cm V s as a consequence of the poor film microstructure. 

Zen et al. synthesized a pentathiophene-based swivel cruciform (76, Figure 16.33), which allows rotation between the cruciform arms [143]. Homogeneous microcrystalline films were processed from solution, and field effect transistors based on this dimer afforded hole mobilities up to 0.012 cm V s . Recently, Cravino et al. demonstrated that high hole mobilities can be obtained with an amorphous oligomer that contains a triarylamine (TAA) core with hexyl-terminated terthiophene arms (77) [144], Hole mobilities up to 0.01 cm V s were measured for vapor-deposited Aims. Furthermore, Saragi et al. compared the field effect mobility of a TAA oligomer series and their spiro-linked analogues [145], All compounds... 

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