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Burke C, Landi A, Troisi A. The dynamic nature of electrostatic disorder in organic mixed ionic and electronic conductors. MATERIALS HORIZONS 2024. [PMID: 39136105 PMCID: PMC11320175 DOI: 10.1039/d4mh00706a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Accepted: 08/07/2024] [Indexed: 08/15/2024]
Abstract
Charge dynamics in disordered media is described invariably assuming that the energy landscape for hopping site energy is stationary. Within the same framework, the correlation between low electronic disorder and high charge mobility is considered extremely robust, despite the emergence of materials with mixed ionic and electronic conductivity (OMIECs) that display high mobility coexisting with large disorder. We show in this work that the disorder of OMIEC polymers is highly dynamical, i.e. the on-site energy for charge transport fluctuates with a characteristic time comparable with that of electron transport. Under these conditions, the disorder of the "frozen" system is not relevant for the charge carrier, whose dynamics are instead controlled by the underlying dynamics of the material. Deep traps exist but have a finite lifetime. The combination of classical simulations and quantum chemical calculations on the nanosecond timescale seems ideal to disclose and characterise the phenomenon.
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Affiliation(s)
- Colm Burke
- Department of Chemistry, University of Liverpool, Liverpool, L69 3BX, UK.
| | - Alessandro Landi
- Department of Chemistry, University of Liverpool, Liverpool, L69 3BX, UK.
- Dipartimento di Chimica e Biologia "Adolfo Zambelli", Università di Salerno, Via Giovanni Paolo II, I-84084 Fisciano, Salerno, Italy
| | - Alessandro Troisi
- Department of Chemistry, University of Liverpool, Liverpool, L69 3BX, UK.
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2
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Yuan Y, Patel RK, Banik S, Reta TB, Bisht RS, Fong DD, Sankaranarayanan SKRS, Ramanathan S. Proton Conducting Neuromorphic Materials and Devices. Chem Rev 2024. [PMID: 39038231 DOI: 10.1021/acs.chemrev.4c00071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Neuromorphic computing and artificial intelligence hardware generally aims to emulate features found in biological neural circuit components and to enable the development of energy-efficient machines. In the biological brain, ionic currents and temporal concentration gradients control information flow and storage. It is therefore of interest to examine materials and devices for neuromorphic computing wherein ionic and electronic currents can propagate. Protons being mobile under an external electric field offers a compelling avenue for facilitating biological functionalities in artificial synapses and neurons. In this review, we first highlight the interesting biological analog of protons as neurotransmitters in various animals. We then discuss the experimental approaches and mechanisms of proton doping in various classes of inorganic and organic proton-conducting materials for the advancement of neuromorphic architectures. Since hydrogen is among the lightest of elements, characterization in a solid matrix requires advanced techniques. We review powerful synchrotron-based spectroscopic techniques for characterizing hydrogen doping in various materials as well as complementary scattering techniques to detect hydrogen. First-principles calculations are then discussed as they help provide an understanding of proton migration and electronic structure modification. Outstanding scientific challenges to further our understanding of proton doping and its use in emerging neuromorphic electronics are pointed out.
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Affiliation(s)
- Yifan Yuan
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Ranjan Kumar Patel
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Suvo Banik
- Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, Illinois 60607, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Tadesse Billo Reta
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ravindra Singh Bisht
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Dillon D Fong
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Subramanian K R S Sankaranarayanan
- Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, Illinois 60607, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Shriram Ramanathan
- Department of Electrical & Computer Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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Wang CI, Maier JC, Jackson NE. Accessing the electronic structure of liquid crystalline semiconductors with bottom-up electronic coarse-graining. Chem Sci 2024; 15:8390-8403. [PMID: 38846409 PMCID: PMC11151863 DOI: 10.1039/d3sc06749a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 05/01/2024] [Indexed: 06/09/2024] Open
Abstract
Understanding the relationship between multiscale morphology and electronic structure is a grand challenge for semiconducting soft materials. Computational studies aimed at characterizing these relationships require the complex integration of quantum-chemical (QC) calculations, all-atom and coarse-grained (CG) molecular dynamics simulations, and back-mapping approaches. However, these methods pose substantial computational challenges that limit their application to the requisite length scales of soft material morphologies. Here, we demonstrate the bottom-up electronic coarse-graining (ECG) of morphology-dependent electronic structure in the liquid-crystal-forming semiconductor, 2-(4-methoxyphenyl)-7-octyl-benzothienobenzothiophene (BTBT). ECG is applied to construct density functional theory (DFT)-accurate valence band Hamiltonians of the isotropic and smectic liquid crystal (LC) phases using only the CG representation of BTBT. By bypassing the atomistic resolution and its prohibitive computational costs, ECG enables the first calculations of the morphology dependence of the electronic structure of charge carriers across LC phases at the ∼20 nm length scale, with robust statistical sampling. Kinetic Monte Carlo (kMC) simulations reveal a strong morphology dependence on zero-field charge mobility among different LC phases as well as the presence of two-molecule charge carriers that act as traps and hinder charge transport. We leverage these results to further evaluate the feasibility of developing mesoscopic, field-based ECG models in future works. The fully CG approach to electronic property predictions in LC semiconductors opens a new computational direction for designing electronic processes in soft materials at their characteristic length scales.
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Affiliation(s)
- Chun-I Wang
- Department of Chemistry, University of Illinois at Urbana-Champaign 505 S Mathews Avenue Urbana Illinois 61801 USA
| | - J Charlie Maier
- Department of Chemistry, University of Illinois at Urbana-Champaign 505 S Mathews Avenue Urbana Illinois 61801 USA
| | - Nicholas E Jackson
- Department of Chemistry, University of Illinois at Urbana-Champaign 505 S Mathews Avenue Urbana Illinois 61801 USA
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Wei Z, Elliott JD, Papaderakis AA, Dryfe RA, Carbone P. Relation between Double Layer Structure, Capacitance, and Surface Tension in Electrowetting of Graphene and Aqueous Electrolytes. J Am Chem Soc 2024; 146:760-772. [PMID: 38153698 PMCID: PMC10785801 DOI: 10.1021/jacs.3c10814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/29/2023]
Abstract
Deciphering the mechanisms of charge storage on carbon-based materials is pivotal for the development of next-generation electrochemical energy storage systems. Graphene, the building block of graphitic electrodes, is an ideal model for probing such processes on a fundamental level. Herein, we investigate the thermodynamics of the graphene/aqueous electrolyte interface by utilizing a multiscale quantum mechanics-classical molecular dynamics (QM/MD) approach to provide insights into the effect of alkali metal ion (Li+) concentration on the interfacial tension (γSL) of the charged graphene/electrolyte interface. We demonstrate that the dependence of γSL on the applied surface charge exhibits an asymmetric behavior relative to the neutral surface. At the positively charged graphene sheet, the electrowetting response is amplified by electrolyte concentration, resulting in a strongly hydrophilic surface. On the contrary, at negative potential bias, γSL shows a weaker response to the charging of the electrode. Changes in γSL greatly affect the total areal capacitance predicted by the Young-Lippmann equation but have a negligible impact on the simulated total areal capacitance, indicating that the EDL structure is not directly correlated with the wettability of the surface and different interfacial mechanisms drive the two phenomena. The proposed model is validated experimentally by studying the electrowetting response of highly oriented pyrolytic graphite over a wide range of electrolyte concentrations. Our work presents the first combined theoretical and experimental study on electrowetting using carbon surfaces, introducing new conceptual routes for the investigation of wetting phenomena under potential bias.
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Affiliation(s)
- Zixuan Wei
- Department
of Chemical Engineering, The University
of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Joshua D. Elliott
- Diamond
Light Source, Diamond House, Harwell Science
and Innovation Park, Oxfordshire, Didcot OX11 ODE, United Kingdom
| | - Athanasios A. Papaderakis
- Department
of Chemistry and Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
| | - Robert A.W. Dryfe
- Department
of Chemistry and Henry Royce Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
| | - Paola Carbone
- Department
of Chemical Engineering, The University
of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Makki H, Burke CA, Troisi A. Microstructural Model of Indacenodithiophene- co-benzothiadiazole Polymer: π-Crossing Interactions and Their Potential Impact on Charge Transport. J Phys Chem Lett 2023; 14:8867-8873. [PMID: 37756473 PMCID: PMC10561260 DOI: 10.1021/acs.jpclett.3c02305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 09/26/2023] [Indexed: 09/29/2023]
Abstract
Morphological and electronic properties of indacenodithiophene-co-benzothiadiazole (IDTBT) copolymer with varying molecular weights are calculated through combined molecular dynamics (MD) and quantum chemical (QC) methods. Our study focuses on the polymer chain arrangements, interchain connectivity pathways, and interplay between morphological and electronic structure properties of IDTBT. Our models, which are verified against GIWAXS measurements, show a considerable number of BT-BT π-π interactions with a (preferential) perpendicular local orientation of polymer chains due to the steric hindrance of bulky side chains around IDT. Although our models predict a noncrystalline structure for IDTBT, the BT-BT (interchain) crossing points show a considerable degree of short-range order in spatial arrangement which most likely result in a mesh-like structure for the polymer and provide efficient pathways for interchain charge transport.
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Affiliation(s)
- Hesam Makki
- Department
of Chemistry and Materials Innovation Factory, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Colm A. Burke
- Department
of Chemistry and Materials Innovation Factory, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Alessandro Troisi
- Department
of Chemistry and Materials Innovation Factory, University of Liverpool, Liverpool L69 7ZD, U.K.
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Di Pasquale N, Finney AR, Elliott JD, Carbone P, Salvalaglio M. Constant chemical potential-quantum mechanical-molecular dynamics simulations of the graphene-electrolyte double layer. J Chem Phys 2023; 158:134714. [PMID: 37031135 DOI: 10.1063/5.0138267] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2023] Open
Abstract
We present the coupling of two frameworks-the pseudo-open boundary simulation method known as constant potential molecular dynamics simulations (CμMD), combined with quantum mechanics/molecular dynamics (QMMD) calculations-to describe the properties of graphene electrodes in contact with electrolytes. The resulting CμQMMD model was then applied to three ionic solutions (LiCl, NaCl, and KCl in water) at bulk solution concentrations ranging from 0.5 M to 6 M in contact with a charged graphene electrode. The new approach we are describing here provides a simulation protocol to control the concentration of electrolyte solutions while including the effects of a fully polarizable electrode surface. Thanks to this coupling, we are able to accurately model both the electrode and solution side of the double layer and provide a thorough analysis of the properties of electrolytes at charged interfaces, such as the screening ability of the electrolyte and the electrostatic potential profile. We also report the calculation of the integral electrochemical double layer capacitance in the whole range of concentrations analyzed for each ionic species, while the quantum mechanical simulations provide access to the differential and integral quantum capacitance. We highlight how subtle features, such as the adsorption of potassium graphene or the tendency of the ions to form clusters contribute to the ability of graphene to store charge, and suggest implications for desalination.
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Affiliation(s)
- Nicodemo Di Pasquale
- Department of Chemical Engineering, Brunel University London, Uxbridge UB8 3PH, United Kingdom
| | - Aaron R Finney
- Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
| | - Joshua D Elliott
- Department of Chemical Engineering, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Paola Carbone
- Department of Chemical Engineering, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Matteo Salvalaglio
- Department of Chemical Engineering, University College London, London WC1E 7JE, United Kingdom
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