Mesophase transitions, surface functionalization, and growth mechanism of semiconducting 6PTTP6 films from solution

The grain structure is compared for films of the organic semiconductor 6PTTP6 prepared in the open air and in a closed, static atmosphere saturated with xylene vapor. The effect of surface functional groups affixed to the dielectric substrate on the grain appearance and film mobility is probed, in order to determine optimal fabrication conditions for films with usable mobility, high on/off ratio, and good uniformity. A single crystal device, also obtained from solution deposition under a particular set of conditions, is characterized and displays an expected higher mobility, >0.1 cm2/Vs. Mesophases are identified in the presence and absence of the xylene and tentatively identified through polarized optical microscopy (POM) . Finally, a preliminary observation of the film evolution using an in situ x-ray diffraction (XRD) technique is reported, and lattice spacings are assigned.