H. Sirringhaus et al., Mobility enhancement in conjugated polymer field-effect transistors through chain alignment in a liquid-crystalline phase, APPL PHYS L, 77(3), 2000, pp. 406-408
A method is demonstrated by which liquid-crystalline self-organization in r
igid-rod nematic conjugated polymers can be used to control the microstruct
ure of the active semiconducting layer in solution-processed polymer thin-f
ilm transistors (TFTs). Enhanced charge carrier mobilities of 0.01-0.02 cm(
2)/V s and good operating stability have been achieved in polyfluorene copo
lymer TFTs by preparing the polymer in a nematic glassy state and by aligni
ng the polymer chains parallel to the transport direction with the help of
an alignment layer. Mobility anisotropies of 5-8 for current flow parallel
and perpendicular to the alignment direction have been observed that are of
the same order of magnitude as optical dichroic ratios. (C) 2000 American
Institute of Physics. [S0003-6951(00)05129-9].