1
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Tiwari V, Li X, Li Z, Jacobs IE, Duan HG, Sirringhaus H, Miller RJD, Jha A. Multitype Electronic Interactions in Precursor Solutions of Molecular Doped P3HT Polymer. J Phys Chem B 2024; 128:3249-3257. [PMID: 38507573 DOI: 10.1021/acs.jpcb.4c00584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Spin-casting of molecularly doped polymer solution mixtures is one of the commonly used methods to obtain conductive organic semiconductor films. In spin-casted films, electronic interaction between the dopant and polymer is one of the crucial factors that dictates the doping efficiency. Here, we investigate excitonic couplings using ultrafast two-dimensional electronic spectroscopy to examine the different types of electronic interactions in ion pairs of the prototype F4TCNQ-doped P3HT polymer system in a precursor solution mixture for spin-casting. Off-diagonal peaks in the 2D spectra clearly establish the excitonic coupling between P3HT+ and F4TCNQ- ions in solution. The observed excitonic coupling is the direct manifestation of a Coulombic interaction between the ion pair. The excited-state lifetime of F4TCNQ- in ion pairs shows biexponential decay at 30 and 200 fs, which hints toward the presence of a heterogeneous population with different interaction strengths. To examine the nature of these different types of interactions in solution mixtures, we study the system using molecular dynamics simulations on a fully solvated model employing the generalized Amber force field. We retrieve three dominant interaction modes of F4TCNQ anions with P3HT: side chain, π-stack, and slipped stack. To quantify these interactions, we complement our studies with electronic structure calculations, which reveal the excitonic coupling strengths of ∼ 75 cm-1 for side chain, ∼ 150 cm-1 for π-π-stack, and ∼69 cm-1 for slipped stack. These various interaction modes provide information about the key geometries of the seed structures in precursor solution mixtures, which may determine the final structures in spin-casted films. The insights gained from our study may guide new strategies to control and ultimately tune Coulomb interactions in polymer-dopant solutions.
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Affiliation(s)
- Vandana Tiwari
- European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Xin Li
- Division of Theoretical Chemistry & Biology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Zheng Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Yangtze Delta Institute of Optoelectronics, Peking University Nantong, Jiangsu 226010, China
| | - Ian E Jacobs
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Hong-Guang Duan
- Department of Physics, School of Physical Science & Technology, Ningbo University, Ningbo 315211, P. R. China
| | - Henning Sirringhaus
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - R J Dwayne Miller
- Departments of Chemistry & Physics, University of Toronto, Toronto M5S 3H6, Canada
| | - Ajay Jha
- Rosalind Franklin Institute, Harwell, Oxfordshire OX11 0QX, U.K
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, U.K
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2
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Verma A, Jackson NE. Assessing molecular doping efficiency in organic semiconductors with reactive Monte Carlo. J Chem Phys 2024; 160:104106. [PMID: 38465678 DOI: 10.1063/5.0197816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/22/2024] [Indexed: 03/12/2024] Open
Abstract
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 on chemistry, processing conditions, and morphology. Computational modeling for an 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 toward 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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Affiliation(s)
- Archana Verma
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Nicholas E Jackson
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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3
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Jacobs M, Krumland J, Valencia AM, Cocchi C. Pulse-Induced Dynamics of a Charge-Transfer Complex from First Principles. J Phys Chem A 2023; 127:8794-8805. [PMID: 37824697 PMCID: PMC10614200 DOI: 10.1021/acs.jpca.3c03709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/18/2023] [Indexed: 10/14/2023]
Abstract
The ultrafast dynamics of charge carriers in organic donor-acceptor interfaces are of primary importance to understanding the fundamental properties of these systems. In this work, we focus on a charge-transfer complex formed by quaterthiophene p-doped by tetrafluoro-tetracyanoquinodimethane and investigate electron dynamics and vibronic interactions also at finite temperatures by applying a femtosecond pulse in resonance with the two lowest energy excitations of the system with perpendicular and parallel polarization with respect to the interface. The adopted ab initio formalism based on real-time time-dependent density-functional theory coupled to Ehrenfest dynamics enables monitoring the dynamical charge transfer across the interface and assessing the role played by the nuclear motion. Our results show that the strong intermolecular interactions binding the complex already in the ground state influence the dynamics, too. The analysis of the nuclear motion involved in these processes reveals the participation of different vibrational modes depending on the electronic states stimulated by the resonant pulse. Coupled donor-acceptor modes mostly influence the excited state polarized across the interface, while intramolecular vibrations in the donor molecule dominate the excitation in the orthogonal direction. The results obtained at finite temperatures are overall consistent with this picture, although thermal disorder contributes to slightly decreasing interfacial charge transfer.
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Affiliation(s)
- Matheus Jacobs
- Physics
Department and IRIS Adlershof, Humboldt-Universität
zu Berlin, Berlin 12489, Germany
| | - Jannis Krumland
- Physics
Department and IRIS Adlershof, Humboldt-Universität
zu Berlin, Berlin 12489, Germany
| | - Ana M. Valencia
- Physics
Department and IRIS Adlershof, Humboldt-Universität
zu Berlin, Berlin 12489, Germany
- Institute
of Physics, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany
| | - Caterina Cocchi
- Physics
Department and IRIS Adlershof, Humboldt-Universität
zu Berlin, Berlin 12489, Germany
- Institute
of Physics, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany
- Center
for Nanoscale Dynamics (CeNaD), Carl von
Ossietzky Universität, Oldenburg 26129, Germany
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4
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Wu EC, Schwartz BJ. Does the Traditional Band Picture Describe the Electronic Structure of Doped Conjugated Polymers? TD-DFT and Natural Transition Orbital Study of Doped P3HT. J Chem Theory Comput 2023; 19:6761-6769. [PMID: 37769199 DOI: 10.1021/acs.jctc.3c00743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Polarons and bipolarons are created when one or two electrons are removed from the π-system of a p-type conjugated polymer, respectively. In the traditional band picture, the creation of a polaron causes two electronic energy levels to move into the band gap. The removal of a second electron to form a bipolaron causes the two intragap states to move further into the gap. Several groups, however, who looked at the energies of the Kohn-Sham orbitals from DFT calculations, have recently argued that the traditional band picture is incorrect for explaining the spectroscopy of doped conjugated polymers. Instead, the DFT calculations suggest that polaron creation causes only one unoccupied state to move into the band gap near the valence band edge while half-filled state in the valence band and the conduction band bend downward in energy. To understand the discrepancy, we performed TD-DFT calculations of polarons and bipolarons on poly(3-hexylthiophene) (P3HT). Not only do the TD-DFT-calculated absorption spectra match the experimental absorption spectra, but an analysis using natural transitional orbitals (NTOs), which provides an approximate one-electron picture from the many-electron TD-DFT results, supports the traditional band picture. Our TD-DFT/NTO analysis indicates that the traditional band picture also works for bipolarons, a system for which DFT calculations were unable to determine the electronic structure.
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Affiliation(s)
- Eric C Wu
- Department of Chemistry and Biochemistry University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry University of California, Los Angeles, Los Angeles, California 90095-1569, United States
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5
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Wu ECK, Salamat CZ, Tolbert SH, Schwartz BJ. Molecular Dynamics Study of the Thermodynamics of Integer Charge Transfer vs Charge-Transfer Complex Formation in Doped Conjugated Polymers. ACS APPLIED MATERIALS & INTERFACES 2022; 14:26988-27001. [PMID: 35657331 DOI: 10.1021/acsami.2c06449] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Molecular dopants such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) can interact with conjugated polymers such as poly(3-hexylthiophene-2,5-diyl) (P3HT) in two different ways: they can undergo integer charge transfer (ICT) or they can form a partial-charge-transfer complex (CTC). Both are seen experimentally, but the CTC has been challenging to characterize, making it difficult to answer questions such as the following. Which polymorph is more stable? Do they have similar barriers for formation? Is there a thermodynamic route to convert one to the other? Here, we study the structure and the thermodynamics of bulk F4TCNQ-doped P3HT with all-atom molecular dynamics simulations, using thermodynamic integration to calculate the relative free energies. We find that the ICT and CTC polymorphs have similar thermodynamic stabilities. The barrier to create the ICT polymorph, however, is lower than that to make the CTC polymorph, because the ICT polymorph has a small critical nucleus, but the critical nucleus for the CTC polymorph is larger than what we can simulate. Moreover, simulated thermal annealing shows that the activation barrier for converting the CTC polymorph to the ICT polymorph is relatively modest. Overall, the simulations explain both the observed structures and the thermodynamics of F4TCNQ-doped P3HT and offer guidelines for targeting the production of a desired polymorph for different applications.
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Affiliation(s)
- Eric Chih-Kuan Wu
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles, California 90095-1569, United States
| | - Charlene Z Salamat
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles, California 90095-1569, United States
| | - Sarah H Tolbert
- Departments of Chemistry and Biochemistry and Materials Science and Engineering University of California, Los Angeles Los Angeles, California 90095-1569, United States
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles, California 90095-1569, United States
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6
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Jacobs IE, Lin Y, Huang Y, Ren X, Simatos D, Chen C, Tjhe D, Statz M, Lai L, Finn PA, Neal WG, D'Avino G, Lemaur V, Fratini S, Beljonne D, Strzalka J, Nielsen CB, Barlow S, Marder SR, McCulloch I, Sirringhaus H. High-Efficiency Ion-Exchange Doping of Conducting Polymers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2102988. [PMID: 34418878 DOI: 10.1002/adma.202102988] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Molecular doping-the use of redox-active small molecules as dopants for organic semiconductors-has seen a surge in research interest driven by emerging applications in sensing, bioelectronics, and thermoelectrics. However, molecular doping carries with it several intrinsic problems stemming directly from the redox-active character of these materials. A recent breakthrough was a doping technique based on ion-exchange, which separates the redox and charge compensation steps of the doping process. Here, the equilibrium and kinetics of ion exchange doping in a model system, poly(2,5-bis(3-alkylthiophen-2-yl)thieno(3,2-b)thiophene) (PBTTT) doped with FeCl3 and an ionic liquid, is studied, reaching conductivities in excess of 1000 S cm-1 and ion exchange efficiencies above 99%. Several factors that enable such high performance, including the choice of acetonitrile as the doping solvent, which largely eliminates electrolyte association effects and dramatically increases the doping strength of FeCl3 , are demonstrated. In this high ion exchange efficiency regime, a simple connection between electrochemical doping and ion exchange is illustrated, and it is shown that the performance and stability of highly doped PBTTT is ultimately limited by intrinsically poor stability at high redox potential.
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Affiliation(s)
- Ian E Jacobs
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Yue Lin
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Yuxuan Huang
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Xinglong Ren
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Dimitrios Simatos
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Chen Chen
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Dion Tjhe
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Martin Statz
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Lianglun Lai
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Peter A Finn
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - William G Neal
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Gabriele D'Avino
- Grenoble Alpes University, CNRS, Grenoble INP, Institut Néel, 25 rue des Martyrs, Grenoble, 38042, France
| | - Vincent Lemaur
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons, B-7000, Belgium
| | - Simone Fratini
- Grenoble Alpes University, CNRS, Grenoble INP, Institut Néel, 25 rue des Martyrs, Grenoble, 38042, France
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons, B-7000, Belgium
| | - Joseph Strzalka
- X-Ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Christian B Nielsen
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Stephen Barlow
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Seth R Marder
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Iain McCulloch
- KAUST Solar Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Henning Sirringhaus
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
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7
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Jacobs IE, Bedolla-Valdez ZI, Rotondo BT, Bilsky DJ, Lewis R, Ayala Oviedo AN, Gonel G, Armitage J, Li J, Moulé AJ. Super-Resolution Photothermal Patterning in Conductive Polymers Enabled by Thermally Activated Solubility. ACS NANO 2021; 15:7006-7020. [PMID: 33733736 DOI: 10.1021/acsnano.1c00070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Doping-induced solubility control (DISC) patterning is a recently developed technique that uses the change in polymer solubility upon doping, along with an optical dedoping process, to achieve high-resolution optical patterning. DISC patterning can produce features smaller than predicted by the diffraction limit; however, no mechanism has been proposed to explain such high resolution. Here, we use diffraction to spatially modulate the light intensity and determine the dissolution rate, revealing a superlinear dependence on light intensity. This rate law is independent of wavelength, indicating that patterning resolution is not dominated by an optical dedoping reaction, as was previously proposed. Instead we show here that the optical patterning mechanism is primarily controlled by the thermal profile generated by the laser. To quantify this effect, the thermal profile and dissolution rate are modeled using a finite-element model and compared against patterned line cross sections as a function of wavelength, laser intensity, and dwell time. Our model reveals that although the laser-generated thermal profile is broadened considerably beyond the profile of the laser, the highly temperature dependent dissolution rate results in selective dissolution near the peak of the thermal profile. Therefore, the key factor in achieving super-resolution patterning is a strongly temperature dependent dissolution rate, a common feature of many polymers. In addition to suggesting several routes to improved resolution, our model also demonstrates that doping is not required for optical patterning of conjugated polymers, as was previously believed. Instead, we demonstrate that superlinear resolution optical patterning should be attainable in any conjugated polymer simply by tuning the solvent quality during patterning, thus extending the applicability of our method to a wide class of materials. We demonstrate the generality of photothermal patterning by writing sub-400 nm features into undoped PffBT4T-2OD.
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Affiliation(s)
- Ian E Jacobs
- Department of Materials Science and Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Zaira I Bedolla-Valdez
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Brandon T Rotondo
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - David J Bilsky
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Ryan Lewis
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Alejandra N Ayala Oviedo
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Goktug Gonel
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - John Armitage
- Optoelectronics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Jun Li
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Adam J Moulé
- Department of Chemical Engineering, University of California Davis, One Shields Avenue, Davis, California 95616, United States
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8
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Arvind M, Tait CE, Guerrini M, Krumland J, Valencia AM, Cocchi C, Mansour AE, Koch N, Barlow S, Marder SR, Behrends J, Neher D. Quantitative Analysis of Doping-Induced Polarons and Charge-Transfer Complexes of Poly(3-hexylthiophene) in Solution. J Phys Chem B 2020; 124:7694-7708. [DOI: 10.1021/acs.jpcb.0c03517] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Malavika Arvind
- Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany
| | - Claudia E. Tait
- Institut für Experimentalphysik, Berlin Joint EPR Lab, Freie Universität Berlin, 14195 Berlin, Germany
| | - Michele Guerrini
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Institut für Physik, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany
| | - Jannis Krumland
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Ana M. Valencia
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Institut für Physik, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany
| | - Caterina Cocchi
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Institut für Physik, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany
| | - Ahmed E. Mansour
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
| | - Norbert Koch
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
| | - Stephen Barlow
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Seth R. Marder
- School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Jan Behrends
- Institut für Experimentalphysik, Berlin Joint EPR Lab, Freie Universität Berlin, 14195 Berlin, Germany
| | - Dieter Neher
- Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam, Germany
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9
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Zapata-Arteaga O, Dörling B, Perevedentsev A, Martín J, Reparaz JS, Campoy-Quiles M. Closing the Stability-Performance Gap in Organic Thermoelectrics by Adjusting the Partial to Integer Charge Transfer Ratio. Macromolecules 2020; 53:609-620. [PMID: 32089566 PMCID: PMC7032849 DOI: 10.1021/acs.macromol.9b02263] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/17/2019] [Indexed: 12/25/2022]
Abstract
Two doping mechanisms are known for the well-studied materials poly(3-hexylthiophene) (P3HT) and poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), namely, integer charge transfer (ICT) and charge transfer complex (CTC) formation. Yet, there is poor understanding of the effect of doping mechanism on thermal stability and the thermoelectric properties. In this work, we present a method to finely adjust the ICT to CTC ratio. Using it, we characterize electrical and thermal conductivities as well as the Seebeck coefficient and the long-term stability under thermal stress of P3HT and PBTTT of different ICT/CTC ratios. We establish that doping through the CTC results in more stable, yet lower conductivity samples compared to ICT doped films. Importantly, moderate CTC fractions of ∼33% are found to improve the long-term stability without a significant sacrifice in electrical conductivity. Through visible and IR spectroscopies, polarized optical microscopy, and grazing-incidence wide-angle X-ray scattering, we find that the CTC dopant molecule access sites within the polymer network are less prone to dedoping upon thermal exposure.
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Affiliation(s)
- Osnat Zapata-Arteaga
- Institute
of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra, Spain
| | - Bernhard Dörling
- Institute
of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra, Spain
| | - Aleksandr Perevedentsev
- Institute
of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra, Spain
| | - Jaime Martín
- POLYMAT
and Polymer Science and Technology Department, Faculty of Chemistry, University of the Basque Country UPV/EHU, Manuel de Lardizabal 3, 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, E-48011 Bilbao, Spain
| | - J. Sebastian Reparaz
- Institute
of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra, Spain
| | - Mariano Campoy-Quiles
- Institute
of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra, Spain
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10
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Su Z, Bedolla-Valdez ZI, Wang L, Rho Y, Chen S, Gonel G, Taurone EN, Moulé AJ, Grigoropoulos CP. High-Speed Photothermal Patterning of Doped Polymer Films. ACS APPLIED MATERIALS & INTERFACES 2019; 11:41717-41725. [PMID: 31619041 DOI: 10.1021/acsami.9b15860] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Organic semiconductors (OSCs) offer a new avenue to the next-generation electronics, but the lack of a scalable and inexpensive nanoscale patterning/deposition technique still limits their use in electronic applications. Recently, a new lithographic etching technique has been introduced that uses molecular dopants to reduce semiconducting polymer solubility in solvents and a direct-write laser to remove dopants locally, enabling rapid OSC etching with diffraction limited resolution. Previous publications postulated that the reaction that enables patterning is a photochemical reaction between photoexcited dopants with neutral solvent molecules. In this work, we analyze the photoinduced dissolution kinetics of F4TCNQ doped P3HT films using time-resolved in situ optical probing. We find two competing mechanisms that control de-doping and dissolution: the first is the photochemical reaction posited in the literature, and the second involves direct heating of the polymer by the laser, inducing increased solubility for both the polymer and dopant. We show that the wavelength-specific photochemical effect is dominant in low photon doses while the photothermal effect is dominant with high excitation rates regardless of laser wavelength. With sufficiently high optical intensity input, the photothermal mechanism can in principle achieve a high writing speed up to 1 m/s. Our findings bring new insights into the mechanisms behind laser direct writing of OSCs based on dopant induced solubility control and enable ultraprecise fabrications of various device configurations in large-scale manufacturing.
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Affiliation(s)
- Zhengliang Su
- Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States
| | - Zaira I Bedolla-Valdez
- Department of Chemical Engineering , University of California , Davis , 95616 California , United States
| | - Letian Wang
- Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States
| | - Yoonsoo Rho
- Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States
| | - Sunny Chen
- Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States
| | - Goktug Gonel
- Department of Chemical Engineering , University of California , Davis , 95616 California , United States
| | - Eric N Taurone
- Department of Chemical Engineering , University of California , Davis , 95616 California , United States
| | - Adam J Moulé
- Department of Chemical Engineering , University of California , Davis , 95616 California , United States
| | - Costas P Grigoropoulos
- Department of Mechanical Engineering , University of California , Berkeley , 94720 California , United States
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11
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Voss MG, Scholes DT, Challa JR, Schwartz BJ. Ultrafast transient absorption spectroscopy of doped P3HT films: distinguishing free and trapped polarons. Faraday Discuss 2019; 216:339-362. [PMID: 31038132 DOI: 10.1039/c8fd00210j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
It is generally presumed that the vast majority of carriers created by chemical doping of semiconducting polymer films are coulombically trapped by the counteranion, with only a small fraction that are free and responsible for the increased conductivity essential for organic electronic applications. At higher doping levels, it is also possible for bipolarons to form, which are expected to be less conductive than single polarons. Unfortunately, there is no simple way to distinguish free polarons, trapped polarons and bipolarons using steady-state spectroscopy. Thus, in this work, we use ultrafast transient absorption spectroscopy to study the dynamics of polarons in 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TNCQ)-doped films of poly(3-hexylthiophene-2,5-diyl) (P3HT) as a function of dopant concentration and excitation wavelength. When exciting on the red side of the polaron P1 transition, our transient absorption spectra and kinetics match well with what is expected for free 2-D-delocalized polarons; the measurements are not consistent with a recent theory of doped conjugated polymer electronic structure that suggests that the half-filled state lies deeper in the conduction band rather than in the bandgap. As we tune the excitation wavelength to the blue, our measurements reveal an increasing amount of slower transient kinetics that are consistent with the presence of coulombically-trapped polarons rather than bipolarons. Taking advantage of their distinct ultrafast relaxation kinetics as a type of action spectroscopy, we are able to extract the steady-state absorption spectra of free and trapped polarons as a function of dopant concentration. By comparing the results to theoretical models, we determine that in F4TCNQ-doped P3HT films, trapped polarons sit ∼0.4 nm away from the anion while free polarons reside between 0.7 and 0.9 nm from the counteranion. Perhaps counterintuitively, the ratio of trapped to free polarons increases at higher doping levels, an observation that is consistent with a plateau in the concentration-dependent conductivity of F4TCNQ-doped P3HT films.
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Affiliation(s)
- Matthew G Voss
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095-1569, USA.
| | - D Tyler Scholes
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095-1569, USA.
| | - J Reddy Challa
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095-1569, USA.
| | - Benjamin J Schwartz
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095-1569, USA.
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12
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Freeman L, Miller P, Sapolsky M, Boucher D. p-Doping Poly(3-hexylthiophene) in Solvent Mixtures. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201800146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Lucas Freeman
- Department of Chemistry and Biochemistry; School of Sciences and Mathematics, College of Charleston; Charleston SC 29401 USA
| | - Paul Miller
- Department of Chemistry and Biochemistry; School of Sciences and Mathematics, College of Charleston; Charleston SC 29401 USA
| | - Marni Sapolsky
- Department of Chemistry and Biochemistry; School of Sciences and Mathematics, College of Charleston; Charleston SC 29401 USA
| | - David Boucher
- Department of Chemistry and Biochemistry; School of Sciences and Mathematics, College of Charleston; Charleston SC 29401 USA
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13
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Freudenberg J, Jänsch D, Hinkel F, Bunz UHF. Immobilization Strategies for Organic Semiconducting Conjugated Polymers. Chem Rev 2018; 118:5598-5689. [DOI: 10.1021/acs.chemrev.8b00063] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jan Freudenberg
- Organisch-Chemisches Institut and Centre of Advanced Materials, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225 and 270, 69120 Heidelberg, FRG
- InnovationLab, Speyerer Str. 4, 69115 Heidelberg, FRG
| | - Daniel Jänsch
- Organisch-Chemisches Institut and Centre of Advanced Materials, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225 and 270, 69120 Heidelberg, FRG
- InnovationLab, Speyerer Str. 4, 69115 Heidelberg, FRG
| | - Felix Hinkel
- Organisch-Chemisches Institut and Centre of Advanced Materials, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225 and 270, 69120 Heidelberg, FRG
| | - Uwe H. F. Bunz
- Organisch-Chemisches Institut and Centre of Advanced Materials, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225 and 270, 69120 Heidelberg, FRG
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14
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Jacobs IE, Moulé AJ. Controlling Molecular Doping in Organic Semiconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703063. [PMID: 28921668 DOI: 10.1002/adma.201703063] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/24/2017] [Indexed: 05/23/2023]
Abstract
The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication-applications beyond those directly analogous to inorganic doping.
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Affiliation(s)
- Ian E Jacobs
- Department of Materials Science, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA
| | - Adam J Moulé
- Department of Chemical Engineering, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA
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15
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Hu X, Lawrence JA, Mullahoo J, Smith ZC, Wilson DJ, Mace CR, Thomas SW. Directly Photopatternable Polythiophene as Dual-Tone Photoresist. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Xiaoran Hu
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - John A. Lawrence
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - James Mullahoo
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Zachary C. Smith
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Daniel J. Wilson
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Charles R. Mace
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Samuel W. Thomas
- Department of Chemistry, Tufts University, 62
Talbot Avenue, Medford, Massachusetts 02155, United States
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16
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Patel SN, Glaudell AM, Peterson KA, Thomas EM, O’Hara KA, Lim E, Chabinyc ML. Morphology controls the thermoelectric power factor of a doped semiconducting polymer. SCIENCE ADVANCES 2017; 3:e1700434. [PMID: 28630931 PMCID: PMC5473677 DOI: 10.1126/sciadv.1700434] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/28/2017] [Indexed: 05/15/2023]
Abstract
The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with F n TCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (σ) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (μ). The Seebeck coefficient (α) is largely independent of OCL. This reveals that, unlike σ, leveraging strategies to improve μ have a smaller impact on α. Our best-performing sample with the largest OCL, vapor-doped PBTTT:F4TCNQ thin film, has a σ of 670 S/cm and an α of 42 μV/K, which translates to a large PF of 120 μW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 μW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics.
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Affiliation(s)
- Shrayesh N. Patel
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Anne M. Glaudell
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Kelly A. Peterson
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Elayne M. Thomas
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Kathryn A. O’Hara
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Eunhee Lim
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
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