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Your search keyword '"Matthews, Campbell S. B."' showing total 6 results
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6 results on '"Matthews, Campbell S. B."'

1. Highly Efficient Blue Host-Free and Host-Guest Organic Light-Emitting Diodes Based on Carbene-Metal-Amides

Author

Conaghan, Patrick J., Matthews, Campbell S. B., Chotard, Florian, Jones, Saul T. E., Greenham, Neil C., Bochmann, Manfred, Credgington, Dan, and Romanov, Alexander S.

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

Carbene-metal-amide type photoemitters based on CF$_3$-substituted carbazolate ligands show sky-blue to deep-blue photoluminescence from charge-transfer excited states. They are suitable for incorporation into organic light-emitting diodes (OLEDs) by thermal vapour deposition techniques, either embedded within a high-triplet-energy host, or used host-free. We report high-efficiency OLEDs with emission ranging from yellow to blue (Commission Internationale de l'\'Eclairage (CIE) coordinates from [0.35, 0.53] to [0.17, 0.17]). The latter show a peak electroluminescence external quantum efficiency (EQE) of 20.9 $\%$ in a polar host. We observe that the relative energies of CT and $^{3}$LE states influence the performance of deep-blue emission from carbene-metal-amide materials. We report prototype host-free blue devices with peak external quantum efficiency of 17.3 $\%$, which maintain high performance at brightness levels of 100 cd m$^{-2}$.

Published
2019
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2. Understanding Spin‐Triplet Excited States in Carbene‐Metal‐Amides.

Author

Reponen, Antti‐Pekka M., Londi, Giacomo, Matthews, Campbell S. B., Olivier, Yoann, Romanov, Alexander S., Greenham, Neil C., and Gillett, Alexander J.

Subjects
DELAYED fluorescence, TIME-resolved spectroscopy, ENERGY levels (Quantum mechanics), PERMITTIVITY
Abstract

Carbene‐metal‐amides (CMAs) are emerging delayed fluorescence materials for organic light‐emitting diode (OLED) applications. CMAs possess fast, efficient emission owing to rapid forward and reverse intersystem crossing (ISC) rates. The resulting dynamic equilibrium between singlet and triplet spin manifolds distinguishes CMAs from most purely organic thermally activated delayed fluorescence emitters. However, direct experimental triplet characterization in CMAs is underutilized, limiting our detailed understanding of the ISC mechanism. In this work, we combine time‐resolved spectroscopy with tuning of state energies through environmental polarity and metal substitution, focusing on the interplay between charge‐transfer (3CT) and local exciton (3LE) triplets. Unlike previous photophysical work, we investigate evaporated host : guest films of CMAs and small‐molecule hosts for increased device relevance. Transient absorption reveals an evolution in the triplet excited‐state absorption (ESA) consistent with a change in orbital character between hosts with differing dielectric constants. Using quantum chemical calculations, we simulate ESAs of the lowest triplet states, highlighting the contribution of only 3CT and donor‐moiety 3LE states to spectral features, with no strong evidence for a low‐lying acceptor‐centered 3LE. Thus, our work provides a blueprint for understanding the role of triplet excited states in CMAs which will enable further intelligent optimization of this promising class of materials. [ABSTRACT FROM AUTHOR]

Published
2024
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5. A solution-processable near-infrared thermally activated delayed fluorescent dye with a fused aromatic acceptor and aggregation induced emission behavior

Author

Congrave, Daniel G., primary, Drummond, Bluebell H., additional, Gu, Qinying, additional, Montanaro, Stephanie, additional, Francis, Haydn, additional, Riesgo-González, Víctor, additional, Zeng, Weixuan, additional, Matthews, Campbell S. B., additional, Dowland, Simon, additional, Wright, Iain A., additional, Grey, Clare P., additional, Friend, Richard H., additional, and Bronstein, Hugo, additional

Published
2022
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6. Highly efficient blue organic light-emitting diodes based on carbene-metal-amides

Author

Saul T. E. Jones, Neil C. Greenham, Dan Credgington, Manfred Bochmann, Alexander S. Romanov, Patrick J. Conaghan, Florian Chotard, Campbell S. B. Matthews, Conaghan, Patrick J [0000-0001-9199-5805], Matthews, Campbell S B [0000-0002-7038-6215], Chotard, Florian [0000-0002-4791-5270], Jones, Saul T E [0000-0001-6007-2530], Greenham, Neil C [0000-0002-2155-2432], Bochmann, Manfred [0000-0001-7736-5428], Credgington, Dan [0000-0003-4246-2118], Romanov, Alexander S [0000-0003-2617-6402], Apollo - University of Cambridge Repository, Matthews, Campbell SB [0000-0002-7038-6215], and Jones, Saul TE [0000-0001-6007-2530]

Subjects
Materials science, Photoluminescence, Metal amides, Electronic materials, Science, General Physics and Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, 010402 general chemistry, 7. Clean energy, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, Article, OLED, Electronic devices, lcsh:Science, Astrophysics::Galaxy Astrophysics, Diode, 3403 Macromolecular and Materials Chemistry, Multidisciplinary, Quenching (fluorescence), 34 Chemical Sciences, 010405 organic chemistry, business.industry, General Chemistry, 0104 chemical sciences, 3402 Inorganic Chemistry, Organometallic chemistry, Excited state, Optical materials, Optoelectronics, Quantum efficiency, lcsh:Q, business, Luminescence
Abstract

Funder: EC | EC Seventh Framework Programm | FP7 Ideas: European Research Council (FP7-IDEAS-ERC - Specific Programme: "Ideas" Implementing the Seventh Framework Programme of the European Community for Research, Technological Development and Demonstration Activities (2007 to 2013)); Grant(s): 338944-GOCAT, Carbene-metal-amides are soluble and thermally stable materials which have recently emerged as emitters in high-performance organic light-emitting diodes. Here we synthesise carbene-metal-amide photoemitters with CF3-substituted ligands to show sky-blue to deep-blue photoluminescence from charge-transfer excited states. We demonstrate that the emission colour can be adjusted from blue to yellow and observe that the relative energies of charge transfer and locally excited triplet states influence the performance of the deep-blue emission. High thermal stability and insensitivity to aggregation-induced luminescence quenching allow us to fabricate organic light-emitting diodes in both host-free and host-guest architectures. We report blue devices with a peak external quantum efficiency of 17.3% in a host-free emitting layer and 20.9% in a polar host. Our findings inform the molecular design of the next generation of stable blue carbene-metal-amide emitters.

Published
2020

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