INSIGHTS INTO THE SOLVATO-/THERMO-PROMOTED INTRAMOLECULAR ELECTRON TRANSFER IN A TTF-σ-TCNQ DYAD WITH AN EXTREMELY LOW HOMO–LUMO GAP

The low-lying states of an organic donor-σ-acceptor dyad, i.e. tetrathiafulvalene-σ-tetracyano-p-quinodimethane (TTF-σ-TCNQ), in gas phase and in various solvents have been investigated by means of hybrid DFT calculations in combination with the conductor-like polarizable continuum model to describe solvent effects. It has been shown that the dyad, though preferring a closed-shell singlet ground state with an eclipsed conformation in gas phase, adopts the charge-separated zwitterionic states with an extended conformation (TTF+-σ-TCNQ-), i.e. open-shell singlet biradical ground state immediately followed by triplet biradical state, in polar solvent ( CH3CN and CH2Cl2 ) as a result of the intramolecular electron transfer (ET) stimulated by solvent polarization. The degree of such intramolecular ET is so strongly dependent on the polarity (dielectric constant) of solvent that the zwitterionic biradical states become more stable with respect to the closed-shell singlet state with increasing polarity of the solvent. As such, the dyad should show a higher ratio of biradicals in more polar solvent and/or at higher temperature and, hence, is chameleonic in nature.

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Open-shell Donors and Closed-shell Acceptors in Organic Solar Cells

10.26434/chemrxiv.14618622 ◽

2021 ◽

Author(s):

Zhongxin Chen ◽

Yuan Li ◽

Wenqiang Li ◽

Weiya Zhu ◽

Miao Zeng ◽

...

Keyword(s):

Solar Cells ◽

Electron Spin Resonance ◽

Electron Spin ◽

Organic Solar Cells ◽

Ground State ◽

Variable Temperature ◽

Closed Shell ◽

Open Shell ◽

Singlet Ground State ◽

Spin Resonance

The active materials of organic solar cells are widely recognized to show closed-shell singlet ground state and their electron spin resonance signals are attributed to the defects and impurities. Herein, we disclose the inherent open-shell singlet ground state of donors and the closed-shell structure of acceptors via the combination of variable temperature NMR, electron spin resonance, superconducting quantum interference device and theoretical calculation, providing a new perspective to understand the intrinsic molecular structure in organic solar cells.

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Open-shell Donors and Closed-shell Acceptors in Organic Solar Cells

10.26434/chemrxiv.14618622.v1 ◽

2021 ◽

Author(s):

Zhongxin Chen ◽

Yuan Li ◽

Wenqiang Li ◽

Weiya Zhu ◽

Miao Zeng ◽

...

Keyword(s):

Solar Cells ◽

Electron Spin Resonance ◽

Electron Spin ◽

Organic Solar Cells ◽

Ground State ◽

Variable Temperature ◽

Closed Shell ◽

Open Shell ◽

Singlet Ground State ◽

Spin Resonance

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Negative ion photoelectron spectroscopy confirms the prediction that D3h carbon trioxide (CO3) has a singlet ground state

Chemical Science ◽

10.1039/c5sc03542b ◽

2016 ◽

Vol 7 (2) ◽

pp. 1142-1150 ◽

Cited By ~ 6

Author(s):

David A. Hrovat ◽

Gao-Lei Hou ◽

Bo Chen ◽

Xue-Bin Wang ◽

Weston Thatcher Borden

Keyword(s):

Gas Phase ◽

Ground State ◽

Photoelectron Spectroscopy ◽

Radical Anion ◽

Negative Ion ◽

Singlet Ground State

The CO3 radical anion (CO3˙−) has been formed by electrospraying carbonate dianion (CO32−) into the gas phase.

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Coexistence of Ferromagnetic Coupling and Intramolecular Electron Transfer in a Purely Organic Mixed-Valence Molecule with a Triplet Ground State

Molecular Crystals and Liquid Crystals Science and Technology Section A Molecular Crystals and Liquid Crystals ◽

10.1080/10587259708044558 ◽

1997 ◽

Vol 306 (1) ◽

pp. 125-132 ◽

Cited By ~ 2

Author(s):

Josep Sedó ◽

Daniel Ruiz ◽

Jose Vidal-gancedo ◽

Concepcio Rovira ◽

Jacques Bonvoisin ◽

...

Keyword(s):

Electron Transfer ◽

Ground State ◽

Mixed Valence ◽

Intramolecular Electron Transfer ◽

Ferromagnetic Coupling ◽

Triplet Ground State

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Ultrafast Energy And Electron Transfer In Conjugated Oligomer-Fullerene Molecules

MRS Proceedings ◽

10.1557/proc-665-c7.3 ◽

2001 ◽

Vol 665 ◽

Author(s):

P.A. van Hal ◽

R.A.J. Janssen ◽

G. Lanzani ◽

G. Cerullo ◽

M. Zavelani-Rossi ◽

...

Keyword(s):

Electron Transfer ◽

Energy Transfer ◽

Time Constant ◽

Transfer Reaction ◽

Polar Solvent ◽

Phenylene Vinylene ◽

Intramolecular Electron Transfer ◽

Pump Probe ◽

Energy And Electron Transfer ◽

Probe Spectroscopy

ABSTRACTThe intramolecular photoinduced energy and electron transfer within a fullereneoligothiophene-fullerene triad with nine thiophene units (C60-9T-C60) and an oligo(p-phenylene vinylene)-fullerene dyad with four phenyl groups (OPV4-C60) is investigated with femtosecond pump-probe spectroscopy with sub-10 fs and 200 fs time resolution in solvents of different polarity. Photoexcitation of the π-conjugated oligomer moiety in the triad and dyad results in an ultrafast singlet-energy transfer reaction to create the fullerene singlet-excited state with a time constant of 150-190 fs, irrespective of the polarity of the medium. In a polar solvent, intramolecular electron transfer occurs from the oligomer moiety to the C60 moiety with a time constant of 10-13 ps as a secondary reaction, subsequent to the ultrafast singlet-energy transfer. The charge-separated state has a lifetime of 50-80 ps and recombines to the ground state.

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