1
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Nicolaidou E, Parker AW, Sazanovich IV, Towrie M, Hayes SC. Unraveling Excited State Dynamics of a Single-Stranded DNA-Assembled Conjugated Polyelectrolyte. J Phys Chem Lett 2023; 14:9794-9803. [PMID: 37883808 PMCID: PMC10641883 DOI: 10.1021/acs.jpclett.3c01803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 10/28/2023]
Abstract
Conformational templating of conjugated polyelectrolytes with single-stranded DNAs (ssDNAs) has the prospect of tailoring excited state dynamics for specific optoelectronic applications. We use ultrafast time-resolved infrared spectroscopy to study the photophysics of a cationic polythiophene assembled with different ssDNAs, inducing distinct conformations (flexible disordered structures vs more rigid complexes with increased backbone planarity). Intrachain polarons are always produced upon selective excitation of the polymer, the extent being dependent on backbone torsional order. Polaron formation and decay were monitored through evolution of IR-active vibrational modes that interfere with mid-IR polaron electronic absorption giving rise to Fano-antiresonances. Selective UV excitation of ssDNAs revealed that stacking interactions between thiophene rings and nucleic acid bases can promote the formation of an intermolecular charge transfer complex. The findings inform designers of functional conjugated polymers by identifying that involvement of the scaffold in the photophysics needs to be considered when developing such structures for optoelectronic applications.
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Affiliation(s)
- Eliana Nicolaidou
- Department
of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | - Anthony W. Parker
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Igor V. Sazanovich
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Sophia C. Hayes
- Department
of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
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2
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Cavassin P, Holzer I, Tsokkou D, Bardagot O, Réhault J, Banerji N. Electrochemical Doping in Ordered and Disordered Domains of Organic Mixed Ionic-Electronic Conductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2300308. [PMID: 37086157 DOI: 10.1002/adma.202300308] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/17/2023] [Indexed: 05/03/2023]
Abstract
Conjugated polymers are increasingly used as organic mixed ionic-electronic conductors in electrochemical applications for neuromorphic computing, bioelectronics, and energy harvesting. The design of efficient electrochemical devices relies on large modulations of the polymer conductivity, fast doping/dedoping kinetics, and high ionic uptake. In this work, structure-property relations are established and control of these parameters by the co-existence of order and disorder in the phase morphology is demonstrated. Using in situ time-resolved spectroelectrochemistry, resonant Raman, and terahertz (THz) conductivity measurements, the electrochemical doping in the different morphological domains of poly(3-hexylthiophene) (P3HT) is investigated. The main finding is that bipolarons are found preferentially in disordered polymer regions, where they are formed faster and are thermodynamically more favored. On the other hand, polarons show a preference for ordered domains, leading to drastically different bipolaron/polaron ratios and doping/dedoping dynamics in the distinct regions. A significant enhancement of the electronic conductivity is evident when bipolarons start forming in the disordered regions, while the presence of bipolarons in the ordered regions is detrimental for transport. This study provides significant advances in the understanding of the impact of morphology on the electrochemical doping of conjugated polymers and the induced increase in conductivity.
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Affiliation(s)
- Priscila Cavassin
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Isabelle Holzer
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Demetra Tsokkou
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Olivier Bardagot
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Julien Réhault
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
| | - Natalie Banerji
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern, 3012, Switzerland
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3
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Danielsen SPO, Thompson BJ, Fredrickson GH, Nguyen TQ, Bazan GC, Segalman RA. Ionic Tunability of Conjugated Polyelectrolyte Solutions. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00178] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Scott P. O. Danielsen
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
| | - Brittany J. Thompson
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States
| | - Glenn H. Fredrickson
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
- Materials Department, University of California, Santa Barbara, California 93106, United States
| | - Thuc-Quyen Nguyen
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Guillermo C. Bazan
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
- Materials Department, University of California, Santa Barbara, California 93106, United States
- Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Rachel A. Segalman
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
- Materials Department, University of California, Santa Barbara, California 93106, United States
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4
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Domínguez SE, Vuolle A, Fattori A, Ääritalo T, Cangiotti M, Damlin P, Ottaviani MF, Kvarnström C. Enhancement of charge-assisted hydrogen bond capabilities due to O-alkylation proximity in alkoxy cationic polythiophenes: solution- and solid-state evidence via EPR, AFM and surface free energy. Phys Chem Chem Phys 2022; 24:6011-6025. [PMID: 35199803 DOI: 10.1039/d1cp04792b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the array of applications for cationic polythiophenes (CPTs), there is still a need for structure-function guidelines and mechanistic understanding of their solution- and solid-state properties. This work presents a solution- and solid-state investigation of the effect of O-alkylation proximity on the hydrogen bonding (H-bonding) capabilities of alkoxy-CPTs, based on comparing an imidazolium alkoxy CPT with strong cation-pi, pi+ and positive charge-assisted hydrogen bonding (+CAHB) capabilities (PIMa), with two isothiouronium alkoxy CPTs with two-point +CAHB capabilities (PT1 & PT2), which have short and long alkoxy side chains, respectively. Our results show that a closer proximity of O-alkylation strengthens the +CAHB capabilities of PT1: in aqueous solutions, PT2 aggregates have a stronger interaction with cationic EPR spin probes than aggregates of PIMa and PT1, which in turn show a similar extent of repulsion towards the cationic spin probes. In solid-state, atomic force microscopy (AFM) shows that PIMa generates dendritic structures onto mica, with features of diffusion-limited aggregation (DLA), indicating strong interactions with the anionic substrate due to a high configurational entropy during spreading, regardless of being drop-casted from water or 1,4-dioxane-water (W-DI), despite the latter disturbing H-bonding due to selective solvation. PT1 is also capable of generating dendritic structures resembling ballistic aggregation (BA). However, this occurs only when casting from water, since W-DI generates island-like aggregates resembling attachment limited aggregation (ALA), which is the morphology generated by PT2 regardless of the solvent. Finally, spin-coated films of PIMa and PT1 show similar dispersivity of the surface free energy (SFE), which in turn is larger than that in PT2 films, which are also more affected when casted from W-DI, presenting much larger decreases of dispersivity. These results constitute a novel empirical structure-function guideline that could be useful for optimal design and/or processing of alkoxy CPTs. For example, dendritic patterns have recently gained attention since the colloidal droplet drying is related to engineering applications including inkjet printing, biosensing, and functional material design, while the SFE is relevant for opto- and bio-electronic applications of conjugated polyelectrolytes (CPEs). This information could also be useful when analyzing previous results obtained from alkoxy CPTs with different side chain lengths.
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Affiliation(s)
- Sergio E Domínguez
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MATSURF), University of Turku, 20014 Turku, Finland.
| | - Antti Vuolle
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MATSURF), University of Turku, 20014 Turku, Finland.
| | - Alberto Fattori
- Department of Pure and Applied Sciences (DiSPeA), University of Urbino, 61029 Urbino, Italy
| | - Timo Ääritalo
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MATSURF), University of Turku, 20014 Turku, Finland.
| | - Michela Cangiotti
- Department of Pure and Applied Sciences (DiSPeA), University of Urbino, 61029 Urbino, Italy
| | - Pia Damlin
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MATSURF), University of Turku, 20014 Turku, Finland.
| | - M Francesca Ottaviani
- Department of Pure and Applied Sciences (DiSPeA), University of Urbino, 61029 Urbino, Italy
| | - Carita Kvarnström
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MATSURF), University of Turku, 20014 Turku, Finland.
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5
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Domínguez SE, Kohn B, Ääritalo T, Damlin P, Scheler U, Kvarnström C. Cationic polythiophene-anionic fullerene pair in water and water-dioxane: studies on hydrogen bonding capabilities, kinetic and thermodynamic properties. Phys Chem Chem Phys 2021; 23:21013-21028. [PMID: 34522930 DOI: 10.1039/d0cp05748g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Despite the vast array of solution- and solid-state bio-analytical, bioelectronic and optoelectronic applications of cationic polythiophenes (CPTs), the number of studies focused on the role of hydrogen bonding (H-bonding) between these and other molecules is scarce, regardless of whether H-bonding is expected to play an important role in several such applications. Also, despite the advantages of using cosolvents to systematically examine the molecular interactions, there are no such studies for CPTs to our knowledge. This work presents a steady-state UV-vis/fluorescence spectroscopic, kinetic and thermodynamic study on the H-bonding interactions between a water-soluble, cationic-anionic (isothiouronium-tetraphosphonate), polythiophene-fullerene donor-acceptor pair with two-point, charge-assisted H-bonding (CAHB) capabilities, tuned using water or a 1,4-dioxane-water mixture (W-DI). Both solvents generate photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), spontaneous binding, H-bonding, ground-state complexing via multiple site binding, formation of micelle-like aggregates and equivalence points at a similar concentration of the quencher. However, in comparison with water, W-DI promotes less-ordered, less packed micellar aggregates, due to hydrophobic desolvation of the H-bond and larger solvent displacement during the PT1-4Fo complexation. This would decrease the extent of charge-transfer and the size of the sphere-of-quenching, mainly by displacements or rotations of the H-bonds, instead of elongations, together with a possible larger extent of diffusion-controlled static quenching. At [4Fo] larger than the equivalence point the micelles formed in water do not have available binding sites due to a tighter aggregation, causing a decrease in the quenching efficiency, while the micelles formed in W-DI start showing larger quenching efficiencies, possibly due to an increase in entropy that overcomes the desolvation of the H-bonding. These results could be useful when analyzing outputs from systems including CPTs with H-bonding capabilities, operating in (or casted from) solvents with clear differences in polarity and/or H-bonding capacity.
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Affiliation(s)
- Sergio E Domínguez
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MatSurf), Vatselankatu 2, FI-20014 Turku, Finland.
| | - Benjamin Kohn
- Leibniz-Institut für, University of Turku, D-01069 Dresden, Germany
| | - Timo Ääritalo
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MatSurf), Vatselankatu 2, FI-20014 Turku, Finland.
| | - Pia Damlin
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MatSurf), Vatselankatu 2, FI-20014 Turku, Finland.
| | - Ulrich Scheler
- Leibniz-Institut für, University of Turku, D-01069 Dresden, Germany
| | - Carita Kvarnström
- Department of Chemistry, Turku University Centre for Materials and Surfaces (MatSurf), Vatselankatu 2, FI-20014 Turku, Finland.
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6
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Peterhans L, Nicolaidou E, Diamantis P, Alloa E, Leclerc M, Surin M, Clément S, Rothlisberger U, Banerji N, Hayes SC. Structural and Photophysical Templating of Conjugated Polyelectrolytes with Single-Stranded DNA. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2020; 32:7347-7362. [PMID: 33122875 PMCID: PMC7587141 DOI: 10.1021/acs.chemmater.0c02251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/06/2020] [Indexed: 06/11/2023]
Abstract
A promising approach to influence and control the photophysical properties of conjugated polymers is directing their molecular conformation by templating. We explore here the templating effect of single-stranded DNA oligomers (ssDNAs) on cationic polythiophenes with the goal to uncover the intermolecular interactions that direct the polymer backbone conformation. We have comprehensively characterized the optical behavior and structure of the polythiophenes in conformationally distinct complexes depending on the sequence of nucleic bases and addressed the effect on the ultrafast excited-state relaxation. This, in combination with molecular dynamics simulations, allowed us a detailed atomistic-level understanding of the structure-property correlations. We find that electrostatic and other noncovalent interactions direct the assembly with the polymer, and we identify that optimal templating is achieved with (ideally 10-20) consecutive cytosine bases through numerous π-stacking interactions with the thiophene rings and side groups of the polymer, leading to a rigid assembly with ssDNA, with highly ordered chains and unique optical signatures. Our insights are an important step forward in an effective approach to structural templating and optoelectronic control of conjugated polymers and organic materials in general.
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Affiliation(s)
- Lisa Peterhans
- Department
of Chemistry and Biochemistry, University
of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Eliana Nicolaidou
- Department
of Chemistry, University of Cyprus, P.O. Box 20537, 1678, Nicosia, Cyprus
| | - Polydefkis Diamantis
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Elisa Alloa
- Department
of Chemistry, University of Cyprus, P.O. Box 20537, 1678, Nicosia, Cyprus
| | - Mario Leclerc
- Department
of Chemistry, Université Laval, G1K 7P4 Quebec
City, Quebec, Canada
| | - Mathieu Surin
- Laboratory
for Chemistry of Novel Materials, Center for Innovation in Materials
and Polymers, University of Mons −
UMONS, 20 Place du Parc, B-7000 Mons, Belgium
| | - Sébastien Clément
- Institut
Charles Gerhardt Montpellier, ICGM, UMR 5253 CNRS, Université de Montpellier, Place Eugène Bataillon, F-34095 Montpellier, Cedex
05, France
| | - Ursula Rothlisberger
- Laboratory
of Computational Chemistry and Biochemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Natalie Banerji
- Department
of Chemistry and Biochemistry, University
of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Sophia C. Hayes
- Department
of Chemistry, University of Cyprus, P.O. Box 20537, 1678, Nicosia, Cyprus
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7
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Strakova K, Poblador‐Bahamonde AI, Sakai N, Matile S. Fluorescent Flipper Probes: Comprehensive Twist Coverage. Chemistry 2019; 25:14935-14942. [DOI: 10.1002/chem.201903604] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/01/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Karolina Strakova
- Department of Organic ChemistryUniversity of Geneva Geneva Switzerland
| | | | - Naomi Sakai
- Department of Organic ChemistryUniversity of Geneva Geneva Switzerland
| | - Stefan Matile
- Department of Organic ChemistryUniversity of Geneva Geneva Switzerland
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8
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Portone A, Ganzer L, Branchi F, Ramos R, Caldas MJ, Pisignano D, Molinari E, Cerullo G, Persano L, Prezzi D, Virgili T. Tailoring optical properties and stimulated emission in nanostructured polythiophene. Sci Rep 2019; 9:7370. [PMID: 31089241 PMCID: PMC6517583 DOI: 10.1038/s41598-019-43719-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 11/09/2022] Open
Abstract
Polythiophenes are the most widely utilized semiconducting polymers in organic electronics, but they are scarcely exploited in photonics due to their high photo-induced absorption caused by interchain polaron pairs, which prevents the establishment of a window of net optical gain. Here we study the photophysics of poly(3-hexylthiophene) configured with different degrees of supramolecular ordering, spin-coated thin films and templated nanowires, and find marked differences in their optical properties. Transient absorption measurements evidence a partially-polarized stimulated emission band in the nanowire samples, in contrast with the photo-induced absorption band observed in spin-coated thin films. In combination with theoretical modeling, our experimental results reveal the origin of the primary photoexcitations dominating the dynamics for different supramolecular ordering, with singlet excitons in the nanostructured samples superseding the presence of polaron pairs, which are present in the disordered films. Our approach demonstrates a viable strategy to direct optical properties through structural control, and the observation of optical gain opens the possibility to the use of polythiophene nanostructures as building blocks of organic optical amplifiers and active photonic devices.
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Affiliation(s)
- Alberto Portone
- Dipartimento di Matematica e Fisica "Ennio De Giorgi", Università del Salento, Via Arnesano I-73100, Lecce, Italy.,NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127, Pisa, Italy
| | - Lucia Ganzer
- Dipartimento di Fisica Politecnico di Milano, I-20132, Milano, Italy
| | - Federico Branchi
- Dipartimento di Fisica Politecnico di Milano, I-20132, Milano, Italy.,Max Born Institute, Max-Born-str. 2A, 12489, Berlin, Germany
| | - Rodrigo Ramos
- Instituto de Física, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil.,Centro Universitario das Faculdades Metropolitanas Unidas, São Paulo, SP, Brazil
| | - Marília J Caldas
- Instituto de Física, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil
| | - Dario Pisignano
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127, Pisa, Italy.,Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
| | - Elisa Molinari
- Istituto Nanoscienze CNR-NANO-S3, Via Campi 213/A, I-41125, Modena, Italy.,Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via Campi, 213/a, I-41125, Modena, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica Politecnico di Milano, I-20132, Milano, Italy
| | - Luana Persano
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127, Pisa, Italy.
| | - Deborah Prezzi
- Istituto Nanoscienze CNR-NANO-S3, Via Campi 213/A, I-41125, Modena, Italy.
| | - Tersilla Virgili
- IFN-CNR, c\o Dipartimento di Fisica, di Milano, I-20132, Milano, Italy.
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9
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Danielsen SPO, Nguyen TQ, Fredrickson GH, Segalman RA. Complexation of a Conjugated Polyelectrolyte and Impact on Optoelectronic Properties. ACS Macro Lett 2019; 8:88-94. [PMID: 35619414 DOI: 10.1021/acsmacrolett.8b00924] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Electrostatic assembly of conjugated polyelectrolytes, which combine a π-conjugated polymer backbone with pendant ionic groups, offer an opportunity for tuning materials properties and a new route for formulating concentrated inks for printable electronics. Complex coacervation, a liquid-liquid phase separation upon complexation of oppositely charged polyelectrolytes in solution, is used to form dense suspensions of π-conjugated material. A model system of a cationic conjugated polyelectrolyte poly(3-[6'-{N-butylimidazolium}hexyl]thiophene) bromide and sodium poly(styrenesulfonate) dissolved in tetrahydrofuran-water mixtures was used to investigate this complexation behavior of conjugated polyelectrolytes in terms of electrostatic strength, solvent quality, and polymer concentration. The balance of electrostatic interaction between the oppositely charged polyelectrolytes together with their charge compensating counterions and solvent quality for the hydrophobic π-conjugated backbone leads to a rich phase diagram of soluble complexes, precipitates, and complex coacervates. The conjugated polyelectrolyte in the polyelectrolyte complexes has an increased π-conjugation length and enhanced emissivity, with ideal chain configurations due to the reduction of kink sites and torsional disorder. The advantageous photophysical properties in the dense liquid phases makes the scheme attractive for the large-scale processing of optoelectronic devices, chemical sensors, and bioelectronics components.
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10
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Causa' M, Ramirez I, Martinez Hardigree JF, Riede M, Banerji N. Femtosecond Dynamics of Photoexcited C 60 Films. J Phys Chem Lett 2018; 9:1885-1892. [PMID: 29569924 DOI: 10.1021/acs.jpclett.8b00520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The well known organic semiconductor C60 is attracting renewed attention due to its centimeter-long electron diffusion length and high performance of solar cells containing 95% fullerene, yet its photophysical properties remain poorly understood. We elucidate the dynamics of Frenkel and intermolecular (inter-C60) charge-transfer (CT) excitons in neat and diluted C60 films from high-quality femtosecond transient absorption (TA) measurements performed at low fluences and free from oxygen or pump-induced photodimerization. We find from preferential excitation of either species that the CT excitons give rise to a strong electro-absorption (EA) signal but are extremely short-lived. The Frenkel exciton relaxation and triplet yield strongly depend on the C60 aggregation. Finally, TA measurements on full devices with applied electric field allow us to optically monitor the dissociation of CT excitons into free charges for the first time and to demonstrate the influence of cluster size on the spectral signature of the C60 anion.
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Affiliation(s)
- Martina Causa'
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , 3012 Bern , Switzerland
| | - Ivan Ramirez
- Clarendon Laboratory, Department of Physics , University of Oxford , Parks Road , OX1 3PU , Oxford , United Kingdom
| | - Josue F Martinez Hardigree
- Clarendon Laboratory, Department of Physics , University of Oxford , Parks Road , OX1 3PU , Oxford , United Kingdom
| | - Moritz Riede
- Clarendon Laboratory, Department of Physics , University of Oxford , Parks Road , OX1 3PU , Oxford , United Kingdom
| | - Natalie Banerji
- Department of Chemistry and Biochemistry , University of Bern , Freiestrasse 3 , 3012 Bern , Switzerland
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