Impact of Liquid-Crystalline Chain Alignment on Charge Transport in Conducting Polymers

Abstract

We develop a theoretical model to predict the impact of nematic liquid-crystalline alignment on charge transport in conducting polymer materials. Using polymer field-theoretic modeling, we predict the chain conformations in a polymer liquid-crystalline state as wormlike chains aligning via a Maier–Saupe interaction. The resulting chain conformations are inserted into our theoretical model for charge transport in a conducting polymer material, which has been previously vetted against experimental measurements in amorphous polymer materials. The resulting predictive model provides a foundational approach to assess the potential enhancement in charge mobility arising from chain alignment in a liquid-crystalline phase. We use this model to predict the mobility enhancement with increasing nematic alignment and varying molecular weight. These predictions offer insight into the potential for performance improvement for conducting materials that are processed from a liquid-crystalline state.

Coarse-Graining Organic Semiconductors: The Path to Multiscale Design

“…The methodology employed a Maier–Saupe interaction to derive representative chain conformations, which were then used as input into a phenomenological charge-transport model. It was observed that strong enhancements in charge carrier mobilities resulted from increased nematic alignment, which can be experimentally controlled via material processing …”

“…It was observed that strong enhancements in charge carrier mobilities resulted from increased nematic alignment, which can be experimentally controlled via material processing. 36 At even more strongly CG resolutions appropriate to device length scales, phase-field models provide a useful path forward for accounting for the complexity of thin-film processing in OSCs. An impressive work by Ronsin et al has introduced a phase-field model for characterizing the drying of OSC thin films on structured substrates.…”

Magnetic field induced alignment of macroradical epoxy for enhanced electrical properties

“…This proposed model is most directly relevant to liquidcrystalline and amorphous phases. 11 For many macroradicals, Savoie et al found a strong orientational dependence of the charge transfer rate in this class of materials. 12 Formation of the organized structure due to induced or self-assembly of localized interacting moieties can also enhance the electrical properties.…”

Modeling the Interplay of Conformational and Electronic Structure in Conjugated Polyelectrolytes

“…Previous computational studies have shown that semiflexible chains in dilute solutions form coils, toroids, racquets, and globules depending on the solvent, temperature, and chain stiffness. − In multichain systems, simulations show semiflexible and anisotropic polymers can have a variety of ordered structures including cylinders, distorted lamella, and lamella, with head-on or face-on interfacial alignment. , In semiconducting conjugated polymers, these different bulk morphologies impact electronic properties substantially, leading to anisotropic charge mobilities . Theoretical models have shown how nematic alignment in conjugated polymers improves charge carrier mobility. , While semiflexible Kremer–Grest CG models can capture the intrinsic stiffness of conjugated polymer backbones, − they cannot capture the biaxial nature of anisotropic interactions between π-conjugated moieties that facilitate the ubiquitous π–π stacking behavior. Recently, we have developed anisotropically interacting, semiflexible CG models tailored to conjugated polymers, reproducing the hierarchy of semiflexible conformations observed in previous semiflexible polymer simulations, while additionally incorporating π-stacking and explicitly coupled dihedrals .…”