Charge transport OTFTs

Among arylamine semiconductors, indolo[3,2-ib]carbazole (5) is an appealing system for studies because it has a relatively large and planar molecular structure to enable facile establishment of higher structural order for charge transport [57, 58]. Earlier, we reported the use of 5,ll-bis(l-naphthyl)indolo[3,2-jb]carbazole, a derivative of 5, as a hole transport material in OLEDs [59]. Because of its sterically encumbered naphthyl substituents, this compound forms only an amorphous film on vacuum deposition, and mobility is low in OTFTs, as expected. 

The charge transport in P3AT nanowires synthesized via self-assembly has been studied by fabricating and testing OTFT devices constructed from a single nanowire, or a network of nanowires [79, 80]. A field-effect mobility of 0.02 cm s ... 

Like 65a-f, cyclic voltammetry data for 67d,e, 73, and 76 showed that these molecules readily accept electrons at low voltages. Thiophene substitution results in a slight shift of reductimi potentials to more negative values with respect to nonthiophene derivative 73, as well as a small decrease in band gap. In addition, the authors obtained device data for these IF dione derivatives in OTFTs. For example, films of 76 showed ambipolar charge transport, having electron and hole mobilities reaching 0.01 and 6 x 10 cvc fW s, respectively. 

In addition to the morphological features of the pentacene layer, the performance of an OTFT is influenced by the microscopic interface environment at the interface between the pentacene layer and a source and drain metallic contact. The electronic parameters of the interface may give rise to an increased contact resistance. Therefore it is important to understand the relationship between the chcrnical/structural characteristics of the OS/metal interface and charge carrier transport in OTFT. For example the difference in mobility between the top-contact and bottom-contact OTFT was associated to the different morphology of the pentacene layer near the metallic contacts [13],... 

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