Fig. 3: Chain orientation patterning in P3HT films.
a Directional crystallisation of a P3HT : BT film by nucleation with BT. Photographs are shown at the indicated times. Also shown is a cross-polarised micrograph recorded at the centre of the obtained P3HT film following sublimation of BT. b Transmitted-light micrographs of a P3HT film laser-patterned at the indicated writing speeds v. Polarised-incidence and cross-polarised micrographs are shown, with the corresponding relative orientations of polariser transmission axes indicated by the arrows. c–f Exemplary spatially resolved Raman spectroscopy analysis of the line patterned using v = 2.5 mm s−1. c Polarised Raman spectra centred on the symmetric C=C stretching mode of the P3HT recorded at the centre of the pattern (black and red lines) and pristine unpatterned area (dotted grey line). d Polarised Raman maps showing maximum intensity IR at ~1450 cm−1 recorded for the indicated excitation/detection polarisations, and (e) the corresponding Raman anisotropy image (AR = IR,||/IR,⊥). f Average Raman anisotropy 〈AR〉 profile across the pattered line. g Maximum values of 〈AR〉 as a function of speed v. Dotted red line indicates the corresponding value obtained for a macroscopically oriented film, as in a. Inset shows the chemical structure of P3HT.
