Photoinduced C70 radical anions in polymer:fullerene blends

Photoinduced polarons in solid films of polymer:fullerene blends were studied by photoluminescence (PL), photoinduced absorption (PIA) and electron spin resonance (ESR). The donor materials used were P3HT and MEH‐PPV. As acceptors we employed PC60BM as reference and various soluble C70‐derivates: PC...

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Bibliographic Details
Published in:Physica status solidi. PSS-RRL. Rapid research letters 2011-03, Vol.5 (3), p.128-130
Main Authors: Sperlich, Andreas, Liedtke, Moritz, Kern, Julia, Kraus, Hannes, Deibel, Carsten, Filippone, Salvatore, Delgado, Juan Luis, Martín, Nazario, Dyakonov, Vladimir
Format: Article
Language:English
Subjects:
Anions
Blends
Buckminsterfullerene
C70
carbon
Charge
Condensed matter: electronic structure, electrical, magnetic, and optical properties
electron spin resonance
Electron states
Exact sciences and technology
Fullerenes
organic solar cells
photoinduced absorption
Physics
Polarons and electron-phonon interactions
Polymer blends
Radicals
Signatures
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Summary:Photoinduced polarons in solid films of polymer:fullerene blends were studied by photoluminescence (PL), photoinduced absorption (PIA) and electron spin resonance (ESR). The donor materials used were P3HT and MEH‐PPV. As acceptors we employed PC60BM as reference and various soluble C70‐derivates: PC70BM, two different diphenylmethano‐[70]fullerene oligoether (C70‐DPM‐OE) and two dimers, C70–C70 and C60–C70. Blend films containing C70 revealed characteristic spectroscopic signatures not seen with C60. Light‐induced ESR showed signals at g ≥ 2.005, assigned to an electron localized on the C70 cage. The formation of C70 radical anions also leads to a subgap PIA band at 0.92 eV, hidden in the spectra of C70‐based P3HT and MEH‐PPV blends, which allows for more exact studies of charge separated states in conjugated polymer:C70 blends. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) Photo‐induced electron transfer from a conjugated polymer to fullerene results in the formation of positive and negative polarons. In most cases, only the positive polaron on a polymer chain could be detected. In this Letter the authors identify the negative polaron on a set of C70 fullerenes and dimers related bulk‐heterojunctions via the NIR absorption band at 0.92 eV.
ISSN:1862-6254
1862-6270
1862-6270
DOI:10.1002/pssr.201105030