Highly Anisotropic P3HT Film Fabricated via Epitaxy on an Oriented Polyethylene Film and Solvent Vapor Treatment

Abstract

To improve the epitaxial crystallization ability of poly(3-hexylthiophene) (P3HT) on a highly oriented polyethylene (PE) substrate, controlled solvent vapor treatment (CSVT) is employed. The anisotropic structures and related optical properties depend not only on the solvent used to prepare the film but also on the subsequent solvent vapor treatment pressure and time. A highly oriented PE film facilitates the "side-on" chain orientation of P3HT with its c axis parallel to the drawing direction of the PE film. The dichroic ratio (DR) of the P3HT film reflected by UV−vis spectra can reach as high as 7.1, which is much larger than the value treated by thermal annealing. Moreover, the excitation bandwidth W, indicating the effective conjugation length and molecular order, shows significant anisotropic features. Solvent used for solution processing with a high boiling point is more favorable for inducing anisotropic multiscale structures. In particular, the oriented structures lead to obvious anisotropic carrier mobility. The carrier mobility of P3HT after CSVT along the PE molecular chain direction is 7.5 times higher than that measured perpendicular to the PE chain direction. This is of great importance in fabricating anisotropic thin films of conjugated polymeric semiconductors with enhanced performance.

Brush Printing Creates Polarized Green Fluorescence: 3D Orientation Mapping and Stochastic Analysis of Conductive Polymer Films

“…28 Wet-processing methods have attracted much attention recently for the preparation of oriented semiconducting polymer films. Blade 29−33 and bar coating, 34,35 solution shearing, 36−38 template-guided coating, 39,40 and epitaxy 41,42 are powerful methods for the preparation of large-area devices and for large-scale manufacturing that utilize printing, coating,…”

“…Wet-processing methods have attracted much attention recently for the preparation of oriented semiconducting polymer films. Blade − and bar coating, , solution shearing, − template-guided coating, , and epitaxy , are powerful methods for the preparation of large-area devices and for large-scale manufacturing that utilize printing, coating, and/or roll-to-roll processes. The brush-printing method is a particularly unique method to obtain an oriented polymer film, which is achieved by simply brushing a polymer solution onto a substrate.…”

Controlling the Chain Orientation and Crystal Form of Poly(9,9-dioctylfluorene) Films for Low-Threshold Light-Pumped Lasers

“…The 2D-GIXRD of PFO-100 measured with the incidence X-ray parallel to the PE chain direction shown in Figure h looks very different from that shown in Figure d, especially in the high-q range close to the expected reflections of PE. This is caused by the change of orientation status of PE films annealed at different temperatures . As seen from the ED patterns in Figure S10, the (002) diffraction arcs of PE in PFO-120 are evidently narrower than those in PFO-100.…”

Designing anisotropic microstructures with spectral density function

“…The representation is physics-aware and highly flexible for both isotropic and anisotropic microstructures with a small set of parameters that can serve as design variables in microstructure design. To quantify the level of anisotropy, we [42] shows that controlled solvent vapor treatment on a highly oriented polyethylene substrate improves crystallization ability and induces strong anisotropy in P3HT films. A holistic design approach requires Processing-Structure-Performance relationships for OPVCs, which is part of our ongoing initiative [43,44] that employs Coarse Grained Molecular Dynamics to understand Processing-Structure relationship and integrate models across the processing-structure-performance chain using SDF based microstructure representation.…”