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Gish MK, Snell K, Thorley KJ, Anthony JE, Johnson JC. Surface Loading Dictates Triplet Production via Singlet Fission in Anthradithiophene Sensitized TiO 2 Films. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:13944-13951. [PMID: 39193258 PMCID: PMC11345824 DOI: 10.1021/acs.jpcc.4c04284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2024] [Revised: 08/06/2024] [Accepted: 08/07/2024] [Indexed: 08/29/2024]
Abstract
Singlet fission, the process of transforming a singlet excited state into two lower energy triplet excited states, is a promising strategy for improving the efficiency of dye-sensitized solar cells. The difficulty in utilizing singlet fission molecules in this architecture is understanding and controlling the orientation of dyes on mesoporous metal oxide surfaces to maximize triplet production and minimize detrimental deactivation pathways, such as electron injection from the singlet or excimer formation. Here, we varied the concentration of loading solutions of two anthradithiophene dyes derivatized with either one or two carboxylic acid groups for binding to a metal oxide surface and studied their photophysics using ultrafast transient absorption spectroscopy. For the single carboxylic acid case, an increase in dye surface coverage led to an increase in apparent triplet excited-state growth via singlet fission, while the same increase in coverage with two carboxylic acids did not. This study represents a step toward controlling the interactions between molecules at mesoporous interfaces.
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Affiliation(s)
- Melissa K. Gish
- Materials,
Chemistry and Computational Sciences Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Katherine Snell
- Materials,
Chemistry and Computational Sciences Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Karl J. Thorley
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Justin C. Johnson
- Materials,
Chemistry and Computational Sciences Directorate, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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2
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He G, Parenti KR, Budden PJ, Niklas J, Macdonald T, Kumarasamy E, Chen X, Yin X, McCamey DR, Poluektov OG, Campos LM, Sfeir MY. Unraveling Triplet Formation Mechanisms in Acenothiophene Chromophores. J Am Chem Soc 2023; 145:22058-22068. [PMID: 37787467 DOI: 10.1021/jacs.3c07082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
The evolution of molecular platforms for singlet fission (SF) chromophores has fueled the quest for new compounds capable of generating triplets quantitatively at fast time scales. As the exploration of molecular motifs for SF has diversified, a key challenge has emerged in identifying when the criteria for SF have been satisfied. Here, we show how covalently bound molecular dimers uniquely provide a set of characteristic optical markers that can be used to distinguish triplet pair formation from processes that generate an individual triplet. These markers are contained within (i) triplet charge-transfer excited state absorption features, (ii) kinetic signatures of triplet-triplet annihilation processes, and (iii) the modulation of triplet formation rates using bridging moieties between chromophores. Our assignments are verified by time-resolved electron paramagnetic resonance (EPR) measurements, which directly identify triplet pairs by their electron spin and polarization patterns. We apply these diagnostic criteria to dimers of acenothiophene derivatives in solution that were recently reported to undergo efficient intermolecular SF in condensed media. While the electronic structure of these heteroatom-containing chromophores can be broadly tuned, the effect of their enhanced spin-orbit coupling and low-energy nonbonding orbitals on their SF dynamics has not been fully determined. We find that SF is fast and efficient in tetracenothiophene but that anthradithiophene exhibits fast intersystem crossing due to modifications of the singlet and triplet excited state energies upon functionalization of the heterocycle. We conclude that it is not sufficient to assign SF based on comparisons of the triplet formation kinetics between monomer and multichromophore systems.
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Affiliation(s)
- Guiying He
- Department of Physics, Graduate Center, City University of New York, New York, New York 10016, United States
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
| | - Kaia R Parenti
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Peter J Budden
- Department of Physics, Graduate Center, City University of New York, New York, New York 10016, United States
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
| | - Jens Niklas
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Thomas Macdonald
- ARC Centre of Excellence in Exciton Science, School of Physics, UNSW Sydney, Sydney, 2052 NSW, Australia
| | - Elango Kumarasamy
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Xing Chen
- Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, P. R. China
| | - Xiaodong Yin
- Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, P. R. China
| | - Dane R McCamey
- ARC Centre of Excellence in Exciton Science, School of Physics, UNSW Sydney, Sydney, 2052 NSW, Australia
| | - Oleg G Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Luis M Campos
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Matthew Y Sfeir
- Department of Physics, Graduate Center, City University of New York, New York, New York 10016, United States
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
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3
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Unger F, Moretti L, Hausch J, Bredehoeft J, Zeiser C, Haug S, Tempelaar R, Hestand NJ, Cerullo G, Broch K. Modulating Singlet Fission by Scanning through Vibronic Resonances in Pentacene-Based Blends. J Am Chem Soc 2022; 144:20610-20619. [DOI: 10.1021/jacs.2c07237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Frederik Unger
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Luca Moretti
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy
| | - Julian Hausch
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Jona Bredehoeft
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Clemens Zeiser
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Sara Haug
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Roel Tempelaar
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Nicholas J. Hestand
- Department of Natural and Applied Sciences, Evangel University, 1111 North Glenstone Avenue, Springfield, Missouri 65802, United States
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy
| | - Katharina Broch
- Institute for Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
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4
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Gish MK, Raulerson EK, Pekarek RT, Greenaway AL, Thorley KJ, Neale NR, Anthony JE, Johnson JC. Resolving electron injection from singlet fission-borne triplets into mesoporous transparent conducting oxides. Chem Sci 2021; 12:11146-11156. [PMID: 34522312 PMCID: PMC8386672 DOI: 10.1039/d1sc03253d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/17/2021] [Indexed: 11/21/2022] Open
Abstract
Photoinduced electron transfer into mesoporous oxide substrates is well-known to occur efficiently for both singlet and triplet excited states in conventional metal-to-ligand charge transfer (MLCT) dyes. However, in all-organic dyes that have the potential for producing two triplet states from one absorbed photon, called singlet fission dyes, the dynamics of electron injection from singlet vs. triplet excited states has not been elucidated. Using applied bias transient absorption spectroscopy with an anthradithiophene-based chromophore (ADT-COOH) adsorbed to mesoporous indium tin oxide (nanoITO), we modulate the driving force and observe changes in electron injection dynamics. ADT-COOH is known to undergo fast triplet pair formation in solid-state films. We find that the electronic coupling at the interface is roughly one order of magnitude weaker for triplet vs. singlet electron injection, which is potentially related to the highly localized nature of triplets without significant charge-transfer character. Through the use of applied bias on nanoITO:ADT-COOH films, we map the electron injection rate constant dependence on driving force, finding negligible injection from triplets at zero bias due to competing recombination channels. However, at driving forces greater than -0.6 eV, electron injection from the triplet accelerates and clearly produces a trend with increased applied bias that matches predictions from Marcus theory with a metallic acceptor.
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Affiliation(s)
- Melissa K Gish
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
| | - Emily K Raulerson
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
| | - Ryan T Pekarek
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
| | - Ann L Greenaway
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
| | - Karl J Thorley
- Department of Chemistry, University of Kentucky Lexington Kentucky 40506 USA
| | - Nathan R Neale
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
| | - John E Anthony
- Department of Chemistry, University of Kentucky Lexington Kentucky 40506 USA
| | - Justin C Johnson
- National Renewable Energy Laboratory 15013 Denver West Pkwy CO 80401 USA
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Thorley KJ, Song Y, Parkin SR, Anthony JE. In Situ Reduction and Functionalization of Polycyclic Quinones. Org Lett 2020; 22:7193-7196. [PMID: 32876459 DOI: 10.1021/acs.orglett.0c02529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Attempts to functionalize polycyclic quinones using lithium diisopropylamide as a base led to the unexpected formation of acenes. This reaction proceeds by electron transfer from the base to the electron deficient quinone, whose radical anion can react with a variety of electrophiles. Siloxy derivatives synthesized by this method could be easily isolated but showed poor photostability. In situ reduced intermediate generation is a convenient approach to functionalization of oxidatively unstable hydroquinones.
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Affiliation(s)
- Karl J Thorley
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States.,Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States
| | - Yang Song
- Department of Chemistry, Centre College, Danville, Kentucky 40422, United States
| | - Sean R Parkin
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - John E Anthony
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States.,Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States
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