Out-of-Phase Electron Spin Echo Studies of Light-Induced Charge-Transfer States in P3HT/PCBM Composite

The light-induced charge-transfer (CT) state in the composite of the conductive polymer poly­(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has been studied by electron spin echo (ESE) spectroscopy. The out-of-phase ESE signal corresponding t...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2015-10, Vol.119 (43), p.13543-13548
Main Authors: Lukina, Ekaterina A, Popov, Alexander A, Uvarov, Mikhail N, Kulik, Leonid V
Format: Article
Language:English
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Summary:The light-induced charge-transfer (CT) state in the composite of the conductive polymer poly­(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has been studied by electron spin echo (ESE) spectroscopy. The out-of-phase ESE signal corresponding to the spin-correlated radical pair P3HT+/PCBM– has been observed in this composite material. The time-domain ESE shape for different delays between the laser flash and the microwave pulse sequence has been analyzed. In order to explain the evolution of the out-of-phase ESE signal as a function of the delay between the microwave pulses, a model of the CT state is proposed. The hole is assumed to be delocalized on the P3HT chain over several thiophene subunits, while the point-dipole approximation is used to describe the interaction with the electron on PCBM. The distribution of distances between the positive and negative charges in the CT state has been evaluated.
ISSN:1520-6106
1520-5207
DOI:10.1021/acs.jpcb.5b02142