Correlating charge and thermoelectric transport to paracrystallinity in conducting polymers

Abstract

The conceptual understanding of charge transport in conducting polymers is still ambiguous due to a wide range of paracrystallinity (disorder). Here, we advance this understanding by presenting the relationship between transport, electronic density of states and scattering parameter in conducting polymers. We show that the tail of the density of states possesses a Gaussian form confirmed by two-dimensional tight-binding model supported by Density Functional Theory and Molecular Dynamics simulations. Furthermore, by using the Boltzmann Transport Equation, we find that transport can be understood by the scattering parameter and the effective density of states. Our model aligns well with the experimental transport properties of a variety of conducting polymers; the scattering parameter affects electrical conductivity, carrier mobility, and Seebeck coefficient, while the effective density of states only affects the electrical conductivity. We hope our results advance the fundamental understanding of charge transport in conducting polymers to further enhance their performance in electronic applications.

Degenerately Doped Semi‐Crystalline Polymers for High Performance Thermoelectrics

“…[ 17–21 ] Thus, it is essential to determine the α–σ relationship because it can help us understand the charge transport mechanism in conducting polymers and optimize the TE performance. [ 22–32 ] There have been many studies on this relationship; for instance, Glaudell et al. found the empirical relationship in which α ∝ σ −1/4 , which successfully fit the experimental data from a variety of doped polymers.…”

The Role of Electrostatic Interaction between Free Charge Carriers and Counterions in Thermoelectric Power Factor of Conducting Polymers: From Crystalline to Polycrystalline Domains

“…The initial P3HT crystal model was adopted from the theoretical study in Ref. [34]. On the basis of this initial structure, we further optimized the atomic positions and lattice parameters by Perdew–Burke–Ernzerhof (PBE) functional [ 35 ] with the dDsC dispersion correction.…”

Approaching Crystal Structure and High Electron Mobility in Conjugated Polymer Crystals

“…Single crystals of π‐conjugated materials are usually regarded as ideal systems to investigate the structure–property relationships both for small molecules and polymers. [ 17–22 ] The structural and energetic disorders in single crystals are usually suppressed than those in thin films. For conjugated polymers, suppressing disorder will promote the charge transport process and hence enhance their electronic performance.…”

“…systemically studied thermoelectric transport in the disordered packed poly(3‐hexylthiophene) (P3HT), using the P3HT crystal structure as the initial model to obtain various disordered structures. [ 21 ] Hence, it is imperative to obtain the conjugated polymer crystals and their supramolecular packing structures. A feasible approach is exploiting the solution‐state aggregation of conjugated polymers to control the crystal growth.…”