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Design of Radical Materials and Systems Towards Opto-Spintronics / JOHN HUDSON

Swansea University Author: JOHN HUDSON

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DOI (Published version): 10.23889/SUThesis.69268

Abstract

Luminescent organic radicals can exploit optical transitions between doublet-spinground and excited states for which potential applications are being explored in more efficient organic light-emitting diodes (OLEDs). In this thesis we investigate how the unpaired electron in radicals enable fundamental...

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Published: Swansea University, Wales, UK 2025
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Evans, E.W., and Meredith, P.
URI: https://cronfa.swan.ac.uk/Record/cronfa69268
Abstract: Luminescent organic radicals can exploit optical transitions between doublet-spinground and excited states for which potential applications are being explored in more efficient organic light-emitting diodes (OLEDs). In this thesis we investigate how the unpaired electron in radicals enable fundamental mechanisms for energy and spin control that could be used in future optoelectronic and opto-spintronic technologies. The design of photon- spin mechanisms towards target functions requires understanding of how the ‘extra spin’ of radicals affects their optical, spin and magnetic properties. Here we study the emergent photo- and spin physics from pairing known closed-shell organic molecules with luminescent open-shell radicals. Following a description of the photophysical mechanisms and magnetic interactions of closed-shell and open-shell molecular species, we set out a re- view on the use of radicals as emissive components in optoelectronics. We then explore the potential of exploiting reversible energy transfer between triplet and doublet states to establish magnetosensitive luminescence and spin polarisation. This is followed by experimental work combining the organometallic deep-blue phosphor FIr6 with the ‘fruit-fly’ TTM-1Cz radical. Förster-mediated triplet-doublet energy transfer with nanosecond life-time ( = 3.1 × 107 s−1), high efficiency (85 ± 25%), and without the need for tripletdiffusion in film blends is demonstrated. Finally, we explore the magnetosensitivity of systems involving energy transfer between radical doublet and acene triplet species. From photophysical and spin-resonance analysis, we focus on the interaction of doublet states with paramagnetic triplet species towards establishing design rules for applications that span from OLEDs to ‘spin sensitisers’ and magnetic-field inclination sensors.
Keywords: Photophysics and Spin Physics of Organic Semiconductors, Spin Chemistry, Quantum Information Science, Spintronics, Functional Materials, Molecular Design
College: Faculty of Science and Engineering

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