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arXiv · 1803.06052

Revealing weak spin-orbit coupling effects on charge carriers in a $π$-conjugated polymer

H. Malissa·R. Miller·D. L. Baird·S. Jamali·G. Joshi·M. Bursch·S. Grimme·J. van Tol·J. M. Lupton·C. Boehme
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Abstract

We measure electrically detected magnetic resonance (EDMR) on organic light-emitting diodes (OLEDs) made of the polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) at room temperature and high magnetic fields, where spectral broadening of the resonance due to spin-orbit coupling (SOC) exceeds that due to the local hyperfine fields. Density-functional-theory calculations on an open-shell model of the material reveal g-tensors of charge-carrier spins in the lowest unoccupied (electron) and highest occupied (hole) molecular orbitals. These tensors are used for simulations of magnetic resonance line-shapes. Besides providing the first quantification and direct observation of SOC effects on charge-carrier states in these weakly SO-coupled hydrocarbons, this procedure demonstrates that spin-related phenomena in these materials are fundamentally monomolecular in nature.

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H. Malissa, R. Miller, D. L. Baird, S. Jamali, G. Joshi, M. Bursch, S. Grimme, J. van Tol, J. M. Lupton, C. Boehme. 2018-03-16. Revealing weak spin-orbit coupling effects on charge carriers in a $π$-conjugated polymer. https://doi.org/10.1103/physrevb.97.161201

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