Diffraction Line-Shape Analysis of Poly(3-dodecylthiophene):  A Study of Layer Disorder through the Liquid Crystalline Polymer Transition

Abstract

The nature of the structural ordering within semicrystalline poly(3-dodecylthiophene) films has been analyzed using a Warren-Averbach line-shape analysis which includes up to five orders of the (h00) lattice reflections. This analysis yields a semiquantitative measure of the volume averaged crystallite sizes, the lattice parameter variations, and the disorder fluctuations. The progression of these quantities has been followed through a liquid crystal polymer (LCP) phase transition which occurs in the vicinity of 60 °C. The pronounced peak width narrowing of the low-order (h00) reflections, observed on heating, is found to be essentially uncorrelated with a theorized annealing-induced increase in average crystallite size. The major contribution to this narrowing arises from systematic variations in the microscopic heterogeneities and fluctuations. Moreover, we observe an anomalously large increase in the higherorder (h00) (h ) 3-5) peak widths at temperatures spanning that of the thermotropic LCP transition. This effect is found to be strongly correlated with a maximum in the disorder fluctuations, and this relationship suggests an underlying mechanism for the nature of the LCP transition.

Vertical confinement and interface effects on the microstructure and charge transport of P3HT thin films

“…A coherence length of 8-10 nm for film thicknesses greater than 20 nm on OTS-treated SiO 2 was confirmed using a more rigorous approach based on the Warren-Averbach Fourier transform peak shape analysis technique. 21,22 These values of domain size are in agreement with values found in literature. 18 Specular geometry only collects diffraction from a small slice of reciprocal space and will miss details of film texture, namely diffraction from misoriented crystalline domains.…”

Dependence of Regioregular Poly(3-hexylthiophene) Film Morphology and Field-Effect Mobility on Molecular Weight

“…The peak width is determined by the crystal size and/or the variations in spacing within a crystal. 32 It seems likely that the low-MW films would have both larger crystals and less variation in d spacing. The annealed samples (Figure 6a) show a case where the film with a substantially larger π-stacking peak has a mobility 80 times lower.…”

Diffraction analysis of highly ordered smectic supramolecules of conjugated rodlike polymers

“…Therefore, the reflection broadening is principally due to lattice parameter fluctuations (microstrains) and the actual crystallite size may be far higher. This order is better than that of PAT:s, such as poly(3-hexylthiophene) (P3HT) (Aasmundtveit et al, 2000), or P3DT (Prosa et al, 1999), or rodlike poly(oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene) oligomers (Dupont et al, 2000).…”

“…Self-assembly, particularly in polyalkylthiophenes, (PAT), results in local order (Tashiro et al, 1991;Prosa et al, 1999;Aasmundtveit et al, 2000) related to improved electronic characteristics, such as high photoluminescence quantum yield (PLQY) (Theander et al, 1999) or charge carrier mobility (Sirringhaus et al, 1999). However, the coiling of PAT resists liquid crystal (LC) and high overall order, and the covalently bonded side chains are permanent.…”