Conjugated polymers with high field effect mobilities

In solution-deposited fihns on dielectrics, the crystalline orientation and morphology depend considerably on polymer-substrate interaction, which can be controlled by modification of the dielectric surface with a self-assembled monolayer (SAM). Cho et al. have controlled the intermolecnlar interaction at the interface between HT-PHT and the dielectric substrate by using SAMs functionalized with various groups (-NH2, -OH, and -CH3) [24]. They have found that, depending on the properties of substrate surface, HT-PHT nanocrystals in the spin-cast films adopt two different orientations of 7t-conjugated planes — parallel and perpendicular to the substrates. These have field-effect mobilities that differ by more than a factor of four and are as high as 0.28 cm V s for jt-conjugated planes parallel to the substrates. 

Bao, Z., Dodabalapur, A., and Lovinger, A.J., Soluble and processable regioregular poly(3-hexylthiophene) for thin film field-effect transistor apphcations with high mobility, Appl. Phys. Lett. 69,4108,1996. Sirringhaus, H., Tessler, N., and Lriend, R. H., Integrated optoelectronic devices based on conjugated polymers. Science 280, 1741, 1998. 

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