Electron and ion transport in semi-dilute conjugated polyelectrolytes: view from a coarse-grained tight binding model

Friday, David; Jackson, Nicholas

doi:10.1039/d2me00285j

Cited by 6 publications

(6 citation statements)

References 80 publications

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“…Future work will focus on bridging the intrachain to interchain gap, which will ultimately need to be addressed by multichain condensed phase simulations. Emerging methods like electronic coarse-graining are likely to be useful here. − In this way, computational methods will be able to inform both the design and processing of radical polymers.…”

Section: Polymer Structures and Crest Explorationmentioning

confidence: 99%

Bridging the Monomer to Polymer Gap in Radical Polymer Design

2023

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Radical polymers bearing open-shell moieties at pendant sites exhibit unique redox and optoelectronic properties that are promising for many organic electronic applications. Nevertheless, gaps remain in relating the electronic properties of repeat units, which can be easily calculated, to the condensedphase charge transport behaviors of these materials. To address this gap, we have performed the first quantum chemical study on a broad swathe of radical polymer design space that explicitly includes the coupling between polymer constraints and radicalmediated intramolecular charge transfer. For this purpose, a chemical space of 64 radical polymer chemistries was constructed based on varying backbone units, open-shell chemistries, and spacer units between the backbone and the radical groups. For each combination of backbone, radical, and spacer, comprehensive conformational sampling was used to calculate expected values of intrachain charge transport using several complementary metrics, including the end-to-end thermal Green's function, Delta−Wye transformed inverse resistance, and the Kirchhoff transport index. We observe that charge transport in radical polymers is primarily driven by the choice radical chemistry, which influences the optimal choice of backbone chemistry and spacer group that mediate radical alignment and avoid the formation of undesired trap states. Given the limited exploration of radical chemistries beyond the TEMPO radical for this class of materials, these findings suggest tremendous opportunities exist for synthetic exploration in radical polymers.

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Section: Polymer Structures and Crest Explorationmentioning

confidence: 99%

Bridging the Monomer to Polymer Gap in Radical Polymer Design

2023

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“…The existence of anisotropic models for molecular and polymeric systems are well-known and could be adapted to improve chemical fidelity at reduced computational cost. 29,67,68 IV. CONCLUSION We have developed a simple but powerful approach to describing doping reaction-induced morphology changes in molecularly doped systems using Reactive MC.…”

Section: Resultsmentioning

confidence: 99%

Assessing Molecular Doping Efficiency in Organic Semiconductors with Reactive Monte Carlo

Verma,

Jackson

2024

Preprint

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The addition of molecular dopants into organic semiconductors (OSCs) is a ubiquitous augmentation strategy to enhance the electrical conductivity of OSCs. Although the importance of optimizing OSC-dopant interactions is well-recognized, chemically generalizable structure-function relationships are difficult to extract due to the sensitivity and dependence of doping efficiency to chemistry, processing conditions, and morphology. Computational modelling for integrated OSC-dopant design is an attractive approach to systematically isolate fundamental relationships, but requires the challenging simultaneous treatment of molecular reactivity and morphology evolution. We present the first computational study to couple molecular reactivity with morphology evolution in a molecularly-doped OSC. Reactive Monte Carlo is employed to examine the evolution of OSC-dopant morphologies and doping efficiency with respect to dielectric, the thermodynamic driving for the doping reaction, and dopant aggregation. We observe that for well-mixed systems with experimentally relevant dielectric constants, doping efficiency is near unity with a very weak dependence on the ionization potential and electron affinity of OSC and dopant, respectively. At experimental dielectric constants, reaction-induced aggregation is observed, corresponding to the well-known insolubility of solution-doped materials. Simulations are qualitatively consistent with a number of experimental studies showing a decrease of doping efficiency with increasing dopant concentration. Finally, we observe that the aggregation of dopants lowers doping efficiency, and thus presents a rational design strategy for maximizing doping efficiency in molecularly doped OSCs. This work represents an important first step towards the systematic integration of molecular reactivity and morphology evolution into the characterization of multi-scale structure-function relationships in molecularly doped OSCs.

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“…For example, density functional theory (DFT) has been used to extract the relationship between atomistic conformation and electrochemical properties such as electronic coupling , and conductance by modeling charge transport at the quantum level. , These studies show the strong dependence of charge transport properties on local conformations (e.g., bond angles and rotations) but are limited to the number and size of conformations that are observable due to the computational cost required to simulate each chain . Furthermore, DFT cannot predict electrochemical properties on its own but needs to be coupled with other methods to account for longer time and length scales associated with transport. ,,− To access higher-length scales (such as those relevant in polymer solutions), it has been shown that it is possible to coarse-grain some of this quantum-level information while retaining the most important features relevant to charge transport such as electronic coupling. , Another way to access longer-length scales is by simulating the charge transport with kinetic Monte Carlo (KMC) models . For example, this method has been used to evaluate the efficiency of charge transport in slurry RFBs, , polymer solar cells, , and polymer field-effect transistors, , but it has only recently been applied to study charge transport in redox-active polymer solutions …”

Section: Introductionmentioning

confidence: 99%

“…25,35,43−45 To access higher-length scales (such as those relevant in polymer solutions), it has been shown that it is possible to coarse-grain some of this quantum-level information while retaining the most important features relevant to charge transport such as electronic coupling. 46,47 Another way to access longer-length scales is by simulating the charge transport with kinetic Monte Carlo (KMC) models. 48 For example, this method has been used to evaluate the efficiency of charge transport in slurry RFBs, 49,50 polymer solar cells, 51,52 and polymer field-effect transistors, 53,54 but it has only recently been applied to study charge transport in redox-active polymer solutions.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Hydrodynamic Interactions and Flow on Charge Transport in Redox-Active Polymer Solutions

Walker,

Sing

2024

J. Phys. Chem. B

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Redox-active polymers (RAPs) are a subclass of polyelectrolytes that can store charge and undergo redox selfexchange reactions. RAPs are of great interest in the field of redox flow batteries (RFBs) due to their ability to quickly charge and discharge, their chemical modularity, and their molecular size. However, designing RAPs for efficient charge transport at the molecular level requires a fundamental understanding of the charge transport mechanisms that occur in RFBs. Previous work from our group has explored these mechanisms, and in this paper, we seek to improve upon the previous model by incorporating both hydrodynamic interactions (HIs) and out-of-equilibrium dynamics, which are both highly pertinent to flow battery systems. We use a hybrid Brownian dynamics and Monte Carlo simulation to model redox-active polymer chains in both dilute and semidilute solutions. This model is used to show that HI is an important feature when charge hopping is not the major mechanism for charge displacement and leads to more rapid segmental and translational motion of polymer chains that expedites charge transport at low polymer concentrations. We demonstrate that strong extensional flows may result in either enhanced or decreased transport depending on the fraction of charges present on the RAP chain. We show that flow not only can promote charge transport by extending polymer conformations but can also suppress nonadjacent charge hopping processes that are important for transport at high charge fractions. Shear flows can similarly enhance charge transport through chain extension, but tumbling dynamics lead to oscillatory displacements that become dominant features with high charge fractions and strong flows.

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Electron and ion transport in semi-dilute conjugated polyelectrolytes: view from a coarse-grained tight binding model

Abstract: Conjugated polyelectrolytes (CPEs) are a rising class of organic mixed ionic-electronic conductors, with applications in bio-interfacing electronics and energy harvesting and storage devices. Here, we employ a quantum mechanically informed...

Cited by 6 publications

References 80 publications

Bridging the Monomer to Polymer Gap in Radical Polymer Design

Bridging the Monomer to Polymer Gap in Radical Polymer Design

Assessing Molecular Doping Efficiency in Organic Semiconductors with Reactive Monte Carlo

Effect of Hydrodynamic Interactions and Flow on Charge Transport in Redox-Active Polymer Solutions

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