1
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Mitra G, Low JZ, Wei S, Francisco KR, Deffner M, Herrmann C, Campos LM, Scheer E. Interplay between Magnetoresistance and Kondo Resonance in Radical Single-Molecule Junctions. Nano Lett 2022; 22:5773-5779. [PMID: 35849010 DOI: 10.1021/acs.nanolett.2c01199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We report transport measurements on tunable single-molecule junctions of the organic perchlorotrityl radical molecule, contacted with gold electrodes at low temperature. The current-voltage characteristics of a subset of junctions shows zero-bias anomalies due to the Kondo effect and in addition elevated magnetoresistance (MR). Junctions without Kondo resonance reveal a much stronger MR. Furthermore, we show that the amplitude of the MR can be tuned by mechanically stretching the junction. On the basis of these findings, we attribute the high MR to an interference effect involving spin-dependent scattering at the metal-molecule interface and assign the Kondo effect to the unpaired spin located in the center of the molecule in asymmetric junctions.
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Affiliation(s)
- Gautam Mitra
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, New York 10027, United States
- Singapore Institute of Manufacturing Technology, 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Sujun Wei
- Department of Chemistry, Queensborough Community College of the City University of New York, Bayside, New York 11364, United States
| | - Karol R Francisco
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Michael Deffner
- Institut für Anorganische und Angewandte Chemie, The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany
| | - Carmen Herrmann
- Institut für Anorganische und Angewandte Chemie, The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elke Scheer
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
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2
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Li L, Low JZ, Wilhelm J, Liao G, Gunasekaran S, Prindle CR, Starr RL, Golze D, Nuckolls C, Steigerwald ML, Evers F, Campos LM, Yin X, Venkataraman L. Highly conducting single-molecule topological insulators based on mono- and di-radical cations. Nat Chem 2022; 14:1061-1067. [PMID: 35798950 DOI: 10.1038/s41557-022-00978-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 05/18/2022] [Indexed: 11/09/2022]
Abstract
Single-molecule topological insulators are promising candidates as conducting wires over nanometre length scales. A key advantage is their ability to exhibit quasi-metallic transport, in contrast to conjugated molecular wires which typically exhibit a low conductance that decays as the wire length increases. Here, we study a family of oligophenylene-bridged bis(triarylamines) with tunable and stable mono- or di-radicaloid character. These wires can undergo one- and two-electron chemical oxidations to the corresponding mono-cation and di-cation, respectively. We show that the oxidized wires exhibit reversed conductance decay with increasing length, consistent with the expectation for Su-Schrieffer-Heeger-type one-dimensional topological insulators. The 2.6-nm-long di-cation reported here displays a conductance greater than 0.1G0, where G0 is the conductance quantum, a factor of 5,400 greater than the neutral form. The observed conductance-length relationship is similar between the mono-cation and di-cation series. Density functional theory calculations elucidate how the frontier orbitals and delocalization of radicals facilitate the observed non-classical quasi-metallic behaviour.
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Affiliation(s)
- Liang Li
- Department of Chemistry, Columbia University, New York, NY, USA
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, NY, USA
| | - Jan Wilhelm
- Institute of Theoretical Physics, University of Regensburg, Regensburg, Germany
| | - Guanming Liao
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, P. R. China
| | | | | | - Rachel L Starr
- Department of Chemistry, Columbia University, New York, NY, USA
| | - Dorothea Golze
- Technische Universität Dresden, Dresden, König-Bau, Germany
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, New York, NY, USA
| | | | - Ferdinand Evers
- Institute of Theoretical Physics, University of Regensburg, Regensburg, Germany.
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, NY, USA.
| | - Xiaodong Yin
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, P. R. China.
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, NY, USA. .,Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA.
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3
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Yin X, Low JZ, Fallon KJ, Paley DW, Campos LM. The butterfly effect in bisfluorenylidene-based dihydroacenes: aggregation induced emission and spin switching. Chem Sci 2019; 10:10733-10739. [PMID: 32153748 PMCID: PMC7020927 DOI: 10.1039/c9sc04096j] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/04/2019] [Indexed: 11/30/2022] Open
Abstract
Linear acenes are a well-studied class of polycyclic aromatic hydrocarbons and their established physical properties have led to their widespread application across the field of organic electronics. However, their quinoidal forms - dihydroacenes - are much less explored and exhibit vastly different photophysical and electronic properties due to their non-planar, cross-conjugated nature. In this work, we present a series of difluorenylidene dihydroacenes which exhibit a butterfly-like structure with a quinoidal skeleton, resulting in comparatively higher optical gaps and lower redox activities than those of their planar analogs. We found that these compounds exhibit aggregation induced emission (AIE), activated through restriction of the "flapping" vibrational mode of the molecules in the solid state. Furthermore, anthracene-containing dihydroacenes exhibit thermally activated ground-state spin switching as evidenced by planarization of the acene core and diradical activity recorded by EPR. These two characteristics in this relatively unexplored class of materials provide new insights for the design of multifunctional materials.
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Affiliation(s)
- Xiaodong Yin
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 102488 , P. R. China
- Department of Chemistry , Columbia University , New York , New York 10027 , USA .
| | - Jonathan Z Low
- Department of Chemistry , Columbia University , New York , New York 10027 , USA .
| | - Kealan J Fallon
- Department of Chemistry , Columbia University , New York , New York 10027 , USA .
| | - Daniel W Paley
- Department of Chemistry , Columbia University , New York , New York 10027 , USA .
| | - Luis M Campos
- Department of Chemistry , Columbia University , New York , New York 10027 , USA .
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4
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Patera LL, Sokolov S, Low JZ, Campos LM, Venkataraman L, Repp J. Resolving the Unpaired‐Electron Orbital Distribution in a Stable Organic Radical by Kondo Resonance Mapping. Angew Chem Int Ed Engl 2019; 58:11063-11067. [DOI: 10.1002/anie.201904851] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Laerte L. Patera
- Institute of Experimental and Applied PhysicsUniversity of Regensburg 93053 Regensburg Germany
| | - Sophia Sokolov
- Institute of Experimental and Applied PhysicsUniversity of Regensburg 93053 Regensburg Germany
| | - Jonathan Z. Low
- Department of ChemistryColumbia University New York NY 10027 USA
| | - Luis M. Campos
- Department of ChemistryColumbia University New York NY 10027 USA
| | - Latha Venkataraman
- Department of ChemistryColumbia University New York NY 10027 USA
- Department of Applied Physics and Applied MathematicsColumbia University New York NY 10027 USA
| | - Jascha Repp
- Institute of Experimental and Applied PhysicsUniversity of Regensburg 93053 Regensburg Germany
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5
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Patera LL, Sokolov S, Low JZ, Campos LM, Venkataraman L, Repp J. Abbildung des Orbitals des ungepaarten Elektrons in einem stabilen, organischen Radikal anhand seiner Kondo‐Resonanz. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Laerte L. Patera
- Institut für Experimentelle und Angewandte PhysikUniversität Regensburg 93053 Regensburg Deutschland
| | - Sophia Sokolov
- Institut für Experimentelle und Angewandte PhysikUniversität Regensburg 93053 Regensburg Deutschland
| | - Jonathan Z. Low
- Department of ChemistryColumbia University New York NY 10027 USA
| | - Luis M. Campos
- Department of ChemistryColumbia University New York NY 10027 USA
| | - Latha Venkataraman
- Department of ChemistryColumbia University New York NY 10027 USA
- Department of Applied Physics and Applied MathematicsColumbia University New York NY 10027 USA
| | - Jascha Repp
- Institut für Experimentelle und Angewandte PhysikUniversität Regensburg 93053 Regensburg Deutschland
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6
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Low JZ, Kladnik G, Patera LL, Sokolov S, Lovat G, Kumarasamy E, Repp J, Campos LM, Cvetko D, Morgante A, Venkataraman L. The Environment-Dependent Behavior of the Blatter Radical at the Metal-Molecule Interface. Nano Lett 2019; 19:2543-2548. [PMID: 30884240 DOI: 10.1021/acs.nanolett.9b00275] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Stable organic radicals have potential applications for building organic spintronic devices. To fulfill this potential, the interface between organic radicals and metal electrodes must be well characterized. Here, through a combined effort that includes synthesis, scanning tunneling microscopy, X-ray spectroscopy, and single-molecule conductance measurements, we comprehensively probe the electronic interaction between gold metal electrodes and a benchtop stable radical-the Blatter radical. We find that despite its open-shell character and having a half-filled orbital close to the Fermi level, the radical is stable on a gold substrate under ultrahigh vacuum. We observe a Kondo resonance arising from the radical and spectroscopic signatures of its half-filled orbitals. By contrast, in solution-based single-molecule conductance measurements, the radical character is lost through oxidation with charge transfer occurring from the molecule to metal. Our experiments show that the stability of radical states can be very sensitive to the environment around the molecule.
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Affiliation(s)
- Jonathan Z Low
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Gregor Kladnik
- Faculty of Mathematics and Physics , University of Ljubljana , Jadranska 19 , SI-1000 Ljubljana , Slovenia
- CNR-IOM Laboratorio Nazionale TASC , Basovizza, SS-14, km 163.5 , I-34012 Trieste , Italy
| | - Laerte L Patera
- Institute of Experimental and Applied Physics , University of Regensburg , 93053 Regensburg , Germany
| | - Sophia Sokolov
- Institute of Experimental and Applied Physics , University of Regensburg , 93053 Regensburg , Germany
| | - Giacomo Lovat
- Department of Applied Physics and Applied Mathematics , Columbia University , New York , New York 10027 , United States
| | - Elango Kumarasamy
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Jascha Repp
- Institute of Experimental and Applied Physics , University of Regensburg , 93053 Regensburg , Germany
| | - Luis M Campos
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
| | - Dean Cvetko
- Faculty of Mathematics and Physics , University of Ljubljana , Jadranska 19 , SI-1000 Ljubljana , Slovenia
- CNR-IOM Laboratorio Nazionale TASC , Basovizza, SS-14, km 163.5 , I-34012 Trieste , Italy
- J. Stefan Institute , Jamova 39 , SI-1000 Ljubljana , Slovenia
| | - Alberto Morgante
- CNR-IOM Laboratorio Nazionale TASC , Basovizza, SS-14, km 163.5 , I-34012 Trieste , Italy
- Department of Physics , University of Trieste , 34127 Trieste , Italy
| | - Latha Venkataraman
- Department of Chemistry , Columbia University , New York , New York 10027 , United States
- Department of Applied Physics and Applied Mathematics , Columbia University , New York , New York 10027 , United States
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7
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Yin X, Zang Y, Zhu L, Low JZ, Liu ZF, Cui J, Neaton JB, Venkataraman L, Campos LM. A reversible single-molecule switch based on activated antiaromaticity. Sci Adv 2017; 3:eaao2615. [PMID: 29098181 PMCID: PMC5659654 DOI: 10.1126/sciadv.aao2615] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 10/05/2017] [Indexed: 05/30/2023]
Abstract
Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope-based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivative that switches to an antiaromatic state with 6-4-6-π electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.
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Affiliation(s)
- Xiaodong Yin
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Yaping Zang
- Department of Applied Physics, Columbia University, New York, NY 10027, USA
| | - Liangliang Zhu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Jonathan Z. Low
- Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Zhen-Fei Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jing Cui
- Department of Applied Physics, Columbia University, New York, NY 10027, USA
| | - Jeffrey B. Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, NY 10027, USA
- Department of Applied Physics, Columbia University, New York, NY 10027, USA
| | - Luis M. Campos
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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8
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Kumarasamy E, Sanders SN, Tayebjee MJY, Asadpoordarvish A, Hele TJH, Fuemmeler EG, Pun AB, Yablon LM, Low JZ, Paley DW, Dean JC, Choi B, Scholes GD, Steigerwald ML, Ananth N, McCamey DR, Sfeir MY, Campos LM. Tuning Singlet Fission in π-Bridge-π Chromophores. J Am Chem Soc 2017; 139:12488-12494. [PMID: 28799752 DOI: 10.1021/jacs.7b05204] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We have designed a series of pentacene dimers separated by homoconjugated or nonconjugated bridges that exhibit fast and efficient intramolecular singlet exciton fission (iSF). These materials are distinctive among reported iSF compounds because they exist in the unexplored regime of close spatial proximity but weak electronic coupling between the singlet exciton and triplet pair states. Using transient absorption spectroscopy to investigate photophysics in these molecules, we find that homoconjugated dimers display desirable excited-state dynamics, with significantly reduced recombination rates as compared to conjugated dimers with similar singlet fission rates. In addition, unlike conjugated dimers, the time constants for singlet fission are relatively insensitive to the interplanar angle between chromophores, since rotation about σ bonds negligibly affects the orbital overlap within the π-bonding network. In the nonconjugated dimer, where the iSF occurs with a time constant >10 ns, comparable to the fluorescence lifetime, we used electron spin resonance spectroscopy to unequivocally establish the formation of triplet-triplet multiexcitons and uncoupled triplet excitons through singlet fission. Together, these studies enable us to articulate the role of the conjugation motif in iSF.
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Affiliation(s)
| | | | - Murad J Y Tayebjee
- Cavendish Laboratory, University of Cambridge , J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | | | - Timothy J H Hele
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States.,Jesus College, Cambridge University , Cambridge CB5 8BL, United Kingdom
| | - Eric G Fuemmeler
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States
| | | | | | | | | | - Jacob C Dean
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | | | - Gregory D Scholes
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | | | - Nandini Ananth
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14850, United States
| | | | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
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9
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Xia J, Sanders SN, Cheng W, Low JZ, Liu J, Campos LM, Sun T. Singlet Fission: Progress and Prospects in Solar Cells. Adv Mater 2017; 29. [PMID: 27973702 DOI: 10.1002/adma.201601652] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 08/07/2016] [Indexed: 05/12/2023]
Abstract
The third generation of photovoltaic technology aims to reduce the fabrication cost and improve the power conversion efficiency (PCE) of solar cells. Singlet fission (SF), an efficient multiple exciton generation (MEG) process in organic semiconductors, is one promising way to surpass the Shockley-Queisser limit of conventional single-junction solar cells. Traditionally, this MEG process has been observed as an intermolecular process in organic materials. The implementation of intermolecular SF in photovoltaic devices has achieved an external quantum efficiency of over 100% and demonstrated significant promise for boosting the PCE of third generation solar cells. More recently, efficient intramolecular SF has been reported. Intramolecular SF materials are modular and have the potential to overcome certain design constraints that intermolecular SF materials possess, which may allow for more facile integration into devices.
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Affiliation(s)
- Jianlong Xia
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Samuel N Sanders
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Wei Cheng
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Jinping Liu
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, New York, 10027, United States
| | - Taolei Sun
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, No. 122 Luoshi Road, Wuhan, 430070, China
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10
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Abstract
Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed with these systems. Through these measurements, we find that increasing the electron affinity of thiophene derivatives, within a family of pentamers, changes the polarity of the charge carriers systematically from holes to electrons, with some systems even showing mid-gap transport characteristics.
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Affiliation(s)
- Jonathan Z Low
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
| | - Brian Capozzi
- Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Jing Cui
- Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Sujun Wei
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
| | - Latha Venkataraman
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA . .,Department of Applied Physics and Applied Mathematics , Columbia University , 500 W 120th St, Mudd 200, MC4701 , New York , NY 10027 , USA .
| | - Luis M Campos
- Department of Chemistry , Columbia University , 3000 Broadway, MC3124 , New York , NY 10027 , USA .
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11
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Capozzi B, Low JZ, Xia J, Liu ZF, Neaton JB, Campos LM, Venkataraman L. Mapping the Transmission Functions of Single-Molecule Junctions. Nano Lett 2016; 16:3949-54. [PMID: 27186894 DOI: 10.1021/acs.nanolett.6b01592] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Charge transport phenomena in single-molecule junctions are often dominated by tunneling, with a transmission function dictating the probability that electrons or holes tunnel through the junction. Here, we present a new and simple technique for measuring the transmission functions of molecular junctions in the coherent tunneling limit, over an energy range of 1.5 eV around the Fermi energy. We create molecular junctions in an ionic environment with electrodes having different exposed areas, which results in the formation of electric double layers of dissimilar density on the two electrodes. This allows us to electrostatically shift the molecular resonance relative to the junction Fermi levels in a manner that depends on the sign of the applied bias, enabling us to map out the junction's transmission function and determine the dominant orbital for charge transport in the molecular junction. We demonstrate this technique using two groups of molecules: one group having molecular resonance energies relatively far from EF and one group having molecular resonance energies within the accessible bias window. Our results compare well with previous electrochemical gating data and with transmission functions computed from first principles. Furthermore, with the second group of molecules, we are able to examine the behavior of a molecular junction as a resonance shifts into the bias window. This work provides a new, experimentally simple route for exploring the fundamentals of charge transport at the nanoscale.
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Affiliation(s)
| | | | - Jianlong Xia
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology , Wuhan 430070, China
| | - Zhen-Fei Liu
- Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Department of Physics, University of California , Berkeley, California 94720, United States
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Department of Physics, University of California , Berkeley, California 94720, United States
- Kavli Energy Nano Sciences Institute at Berkeley , Berkeley, California 94720, United States
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12
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Kumarasamy E, Sanders SN, Pun AB, Vaselabadi SA, Low JZ, Sfeir MY, Steigerwald ML, Stein GE, Campos LM. Properties of Poly- and Oligopentacenes Synthesized from Modular Building Blocks. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02711] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Elango Kumarasamy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Samuel N. Sanders
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew B. Pun
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Saeed Ahmadi Vaselabadi
- Department
of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Jonathan Z. Low
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Matthew Y. Sfeir
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | | | - Gila E. Stein
- Department
of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Luis M. Campos
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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13
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Sanders SN, Kumarasamy E, Pun AB, Trinh MT, Choi B, Xia J, Taffet EJ, Low JZ, Miller JR, Roy X, Zhu XY, Steigerwald ML, Sfeir MY, Campos LM. Quantitative Intramolecular Singlet Fission in Bipentacenes. J Am Chem Soc 2015; 137:8965-72. [DOI: 10.1021/jacs.5b04986] [Citation(s) in RCA: 272] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Samuel N. Sanders
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elango Kumarasamy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Andrew B. Pun
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - M. Tuan Trinh
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Bonnie Choi
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Jianlong Xia
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Elliot J. Taffet
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Jonathan Z. Low
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | | | - Xavier Roy
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - X.-Y. Zhu
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | | | | | - Luis M. Campos
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
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Busby E, Xia J, Wu Q, Low JZ, Song R, Miller JR, Zhu XY, Campos LM, Sfeir MY. A design strategy for intramolecular singlet fission mediated by charge-transfer states in donor-acceptor organic materials. Nat Mater 2015; 14:426-33. [PMID: 25581625 DOI: 10.1038/nmat4175] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 11/18/2014] [Indexed: 05/21/2023]
Abstract
The ability to advance our understanding of multiple exciton generation (MEG) in organic materials has been restricted by the limited number of materials capable of singlet fission. A particular challenge is the development of materials that undergo efficient intramolecular fission, such that local order and strong nearest-neighbour coupling is no longer a design constraint. Here we address these challenges by demonstrating that strong intrachain donor-acceptor interactions are a key design feature for organic materials capable of intramolecular singlet fission. By conjugating strong-acceptor and strong-donor building blocks, small molecules and polymers with charge-transfer states that mediate population transfer between singlet excitons and triplet excitons are synthesized. Using transient optical techniques, we show that triplet populations can be generated with yields up to 170%. These guidelines are widely applicable to similar families of polymers and small molecules, and can lead to the development of new fission-capable materials with tunable electronic structure, as well as a deeper fundamental understanding of MEG.
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Affiliation(s)
- Erik Busby
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jianlong Xia
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Qin Wu
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Jonathan Z Low
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Rui Song
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - John R Miller
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - X-Y Zhu
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Luis M Campos
- 1] Energy Frontier Research Center, Columbia University, New York, New York 10027, USA [2] Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Matthew Y Sfeir
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA
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Busby E, Xia J, Low JZ, Wu Q, Hoy J, Campos LM, Sfeir MY. Fast Singlet Exciton Decay in Push–Pull Molecules Containing Oxidized Thiophenes. J Phys Chem B 2015; 119:7644-50. [DOI: 10.1021/jp511704r] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Erik Busby
- Department
of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Jianlong Xia
- Department
of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Jonathan Z. Low
- Department
of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Qin Wu
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Jessica Hoy
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
- Condensed
Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Luis M. Campos
- Department
of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Matthew Y. Sfeir
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
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