EPR study of radical anions of C60 and C70

Friedrich, Jan O.; Schweitzer, P.; Dinse, Klaus−Peter; Rapta, Peter; Staško, Andrej

doi:10.1007/bf03162622

Cited by 22 publications

(12 citation statements)

References 12 publications

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“…Thus, a difference in the g-value is an indication of the different electronic structure of molecular orbitals in C 60 vs C 70 anion radicals. Previous studies of C 70 − in the liquid phase at room temperatures 10,16 demonstrate that the average gfactor of C 70 − is higher than the g-factor of C 60 − .This positive shift of the g-factors in solution for C 70 − relative to C 60 − has been explained on the basis of the static Jahn-Teller effect 17,18 . It is probable that Jahn-Teller dynamics in the solid phase is quite different for C 60 and C 70 molecules, which might contribute to different signs of the g-value shifts 18 .…”

Section: Methodsmentioning

confidence: 93%

Spin Signatures of Photogenerated Radical Anions in Polymer−[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

et al. 2010

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Charged polarons in thin films of polymer-fullerene composites are investigated by light-induced electron paramagnetic resonance (EPR) at 9.5 GHz (X-band) and 130 GHz (D-band). The materials studied were poly(3-hexylthiophene) (PHT), [6,6]-phenyl-C61-butyric acid methyl ester (C(60)-PCBM), and two different soluble C(70)-derivates: C(70)-PCBM and diphenylmethano[70]fullerene oligoether (C(70)-DPM-OE). The first experimental identification of the negative polaron localized on the C(70)-cage in polymer-fullerene bulk heterojunctions has been obtained. When recorded at conventional X-band EPR, this signal is overlapping with the signal of the positive polaron, which does not allow for its direct experimental identification. Owing to the superior spectral resolution of the high frequency D-band EPR, we were able to separate light-induced signals from P(+) and P(-) in PHT-C(70) bulk heterojunctions. Comparing signals from C(70)-derivatives with different side-chains, we have obtained experimental proof that the polaron is localized on the cage of the C(70) molecule.

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Section: Methodsmentioning

confidence: 93%

Spin Signatures of Photogenerated Radical Anions in Polymer−[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

et al. 2010

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“…A substantially larger isotropic g-value of C 70 in comparison to C 60 had already been obtained from liquid solution EPR measurements. [84][85] It should be noted that these were not studies of the PCBM fullerene derivatives. Finally, a D-band study succeeded in distinguishing the radical signals of polymer P3HT and fullerene PC 71 BM by subtracting the P3HT signal which was recorded under identical conditions on a P3HT: PC 61 BM blend (Figure 7).…”

Section: Light-induced Charge Carriers In Opvsmentioning

confidence: 99%

Charge Transfer Processes in OPV Materials as Revealed by EPR Spectroscopy

Niklas

Poluektov

2017

Advanced Energy Materials

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Understanding charge separation and charge transport at a molecular level is crucial for improving the efficiency of organic photovoltaic (OPV) cells. Under illumination of Bulk Heterojunction (BHJ) blends of polymers and fullerenes, various paramagnetic species are formed including polymer and fullerene radicals, radical pairs, and photoexcited triplet states. Light-induced Electron Paramagnetic Resonance (EPR) spectroscopy is ideally suited to study these states in BHJ due to its selectivity in probing the paramagnetic intermediates. Advanced techniques like pulsed EPR and ENDOR spectroscopy allow the determination of hyperfine coupling tensors, while high-frequency EPR allows the EPR signals of the individual species to be resolved and their g-tensors to be determined. The magnetic resonance parameters of the various polymer donors reveal details about the delocalization of the positive polaron which is important for the efficient charge separation in BHJ systems. Time-resolved EPR can contribute to the study of the dynamics of charge separation, charge transfer and recombination in BHJ by probing the unique spectral signatures of charge transfer and triplet states. EPR also has the potential to allow characterization of intermediates and products of BHJ degradation.

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“…131 Stasko and co-workers proposed that strong solvation might be sufficient to lift the (t 1u ) 1 degeneracy, 361 and Jones, Kadish, and coworkers have tended toward this view. 133,171 However, it is inconsistent with the large body of data on the broad signal discussed above.…”

Section: Origins Of Sharp Signalsmentioning

confidence: 99%

Discrete Fulleride Anions and Fullerenium Cations

2000

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His research interests include reactive cation and superacid chemistry with inert carborane counterions, ionic liquids, bioinorganic chemistry, spin-coupling phenomena, fullerene chemistry, and new carbon-or porphyrin-based materials. He is a Sloan Fellow, a Dreyfus Teacher−Scholar Awardee, and a Guggenheim Fellow. Robert Bolskar received his B.S. degree in Chemistry from Carroll College in Waukesha, WI, in 1992. He earned his Ph.D. degree at the University of Southern California in Los Angeles under the direction of Christopher Reed in 1997, investigating the synthetic redox chemistry of fullerene anions and cations. In 1998 he moved to the University of California, Riverside, as Managing Research Associate. He is currently Senior Chemist at TDA Research in Wheat Ridge, CO. His research interests include the chemistry and physics of fullerene compounds, supramolecular chemistry, strongly oxidizing systems, and electrophilic cations.

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EPR study of radical anions of C60 and C70

Cited by 22 publications

References 12 publications

Spin Signatures of Photogenerated Radical Anions in Polymer−[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

Spin Signatures of Photogenerated Radical Anions in Polymer−[70]Fullerene Bulk Heterojunctions: High Frequency Pulsed EPR Spectroscopy

Charge Transfer Processes in OPV Materials as Revealed by EPR Spectroscopy

Discrete Fulleride Anions and Fullerenium Cations

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