The importance of intra-molecular electron spin relaxation in small molecular semiconductors

Abstract

Electron spin relaxation rate (eSR) is investigated on several organic semiconductors of different morphologies and molecular structures, using avoided level crossing muon spectroscopy as a local spin probe. We find that two functionalized acenes (polycrystalline tri(isopropyl)silyl-pentacene and amorphous 5,6,11,12-tetraphenyltetracene) exhibit eSRs with an Arrhenius-like temperature dependence, each with two characteristic energy scales similar to those expected from vibrations. Polycrystalline tris(8-hydroxyquinolate)gallium shows a similar behavior. The observed eSR for these molecules is no greater than 0.85 MHz at 300 K. The variety of crystal structures and transport regimes that these molecules possess, as well as the local nature of the probe, strongly suggest an intra-molecular phenomenon general to many organic semiconductors, contrasting the commonly assumed spin relaxation models based on inter-molecular charge carrier transport.

References in corpus (3)

• Geometrical spin dephasing in quantum dots
• Elucidating the role of hyperfine interactions on organic magnetoresistance using deuterated aluminium tris(8-hydroxyquinoline)
• Geometric phases in semiconductor spin qubits: Manipulations and decoherence

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• Distinguishing Spin Relaxation Mechanisms in Organic Semiconductors
• The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source
• Magnetoresistance from quenching of spin quantum correlation in organic semiconductors