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

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.

arXiv comment6 pages, 4 figures

References in corpus (8)

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• Tuning the effective spin-orbit coupling in molecular semiconductors
• Modulation frequency dependence of continuous-wave optically/electrically detected magnetic resonance
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• Spin-dependent processes at the crystalline Si-SiO_2 interface at high magnetic fields
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• Morphology effects on spin-dependent transport and recombination in polyfluorene thin films
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• OLEDs as models for bird magnetoception: detecting electron spin resonance in geomagnetic fields
• High-Field Magnetoresistance of Organic Semiconductors
• Perdeuteration of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (d-MEHPPV): control of microscopic charge-carrier spin-spin coupling and of magnetic-field effects in optoelectronic devices
• Floquet spin states in OLEDs
• Sub-micron spin-based magnetic field imaging with an organic light emitting diode
• Molecular Tuning of the Magnetic Response in Organic Semiconductors
• Two-photon absorption in a two-level system enabled by noise
• Tuning effective hyperfine fields in PEDOT:PSS thin films by doping
• Spin relaxation dynamics of radical-pair processes at low magnetic fields
• Spin-Dependent Charge-Carrier Recombination Processes in Tris(8-Hydroxyquinolinato) Aluminum
• Non-Bloch-Siegert-type power-induced shift of two-photon electron paramagnetic resonances of charge-carrier spin states in an OLED