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Isomeric modulation of thermally activated delayed fluorescence in dibenzo[ a, c ]phenazine-based (deep) red emitters † (2024)
Journal Article
Brebels, S., Cardeynaels, T., Jackers, L., Kuila, S., Penxten, H., Salthouse, R. J., …Maes, W. (2024). Isomeric modulation of thermally activated delayed fluorescence in dibenzo[ a, c ]phenazine-based (deep) red emitters †. Journal of Materials Chemistry C Materials for optical and electronic devices, https://doi.org/10.1039/d4tc01214c

A series of four emissive regio-isomers are synthesized based on the dibenzo[a, c]phenazine-11,12-dicarbonitrile (DBPzCN) acceptor scaffold and a triphenylamine (TPA) donor. Density functional theory is utilized to compare the relative differences in... Read More about Isomeric modulation of thermally activated delayed fluorescence in dibenzo[ a, c ]phenazine-based (deep) red emitters †.

Key requirements for ultraefficient sensitization in hyperfluorescence organic light-emitting diodes (2024)
Journal Article
Stavrou, K., Franca, L. G., Danos, A., & Monkman, A. P. (2024). Key requirements for ultraefficient sensitization in hyperfluorescence organic light-emitting diodes. Nature Photonics, 18(6), 554-561. https://doi.org/10.1038/s41566-024-01395-1

Blue organic light-emitting diode (OLED) technology requires further advancements, and hyperfluorescent (HF) OLEDs have emerged as a promising solution to address stability and colour-purity concerns. A key factor influencing the performance of HF-OL... Read More about Key requirements for ultraefficient sensitization in hyperfluorescence organic light-emitting diodes.

Exploring the Early Time Behavior of the Excited States of an Archetype Thermally Activated Delayed Fluorescence Molecule (2024)
Journal Article
Franca, L., Danos, A., Saxena, R., Kuila, S., Stavrou, K., Li, C., …Monkman, A. P. (2024). Exploring the Early Time Behavior of the Excited States of an Archetype Thermally Activated Delayed Fluorescence Molecule. Journal of Physical Chemistry Letters, 15(6), 1734-1740. https://doi.org/10.1021/acs.jpclett.4c00030

Optical pump–probe techniques allow for an in-depth study of dark excited states. Here, we utilize them to map and gain insights into the excited states involved in the thermally activated delayed fluorescence (TADF) mechanism of a benchmark TADF emi... Read More about Exploring the Early Time Behavior of the Excited States of an Archetype Thermally Activated Delayed Fluorescence Molecule.

Peripheral halogen atoms in multi-resonant thermally activated delayed fluorescence emitters: the role of heavy atoms in intermolecular interactions and spin orbit coupling (2023)
Journal Article
Miranda-Salinas, H., Wang, J., Danos, A., Matulaitis, T., Stavrou, K., Monkman, A. P., & Zysman-Colman, E. (2024). Peripheral halogen atoms in multi-resonant thermally activated delayed fluorescence emitters: the role of heavy atoms in intermolecular interactions and spin orbit coupling. Journal of Materials Chemistry C Materials for optical and electronic devices, 12(6), 1996-2006. https://doi.org/10.1039/d3tc04394k

Multi-resonant thermally activated delayed fluorescence materials (MR-TADF) can show narrow-band emission with high photoluminescence quantum efficiency, desirable for applications in organic light emitting diodes (OLEDS). However, they frequently su... Read More about Peripheral halogen atoms in multi-resonant thermally activated delayed fluorescence emitters: the role of heavy atoms in intermolecular interactions and spin orbit coupling.

Intramolecular locking and coumarin insertion: a stepwise approach for TADF design (2023)
Journal Article
Paredis, S., Cardeynaels, T., Brebels, S., Deckers, J., Kuila, S., Lathouwers, A., …Maes, W. (2023). Intramolecular locking and coumarin insertion: a stepwise approach for TADF design. Physical Chemistry Chemical Physics, https://doi.org/10.1039/d3cp03695b

Three novel TADF (thermally activated delayed fluorescence) emitters based on the well-studied Qx-Ph-DMAC fluorophore are designed and synthesized. The photophysical properties of these materials are studied from a theoretical and experimental point... Read More about Intramolecular locking and coumarin insertion: a stepwise approach for TADF design.

Covalently linked pyrene antennas for optically dense yet aggregation-resistant light-harvesting systems (2023)
Journal Article
Salah, L., Makhseed, S., Ghazal, B., Abdel Nazeer, A., Etherington, M. K., Ponseca Jr., C. S., …Shuaib, A. (2023). Covalently linked pyrene antennas for optically dense yet aggregation-resistant light-harvesting systems. Physical Chemistry Chemical Physics, 25(36), 24878-24882. https://doi.org/10.1039/d3cp02586a

In this study we present a novel energy transfer material inspired by natural light-harvesting antenna arrays, zinc(II) phthalocyanine-pyrene (ZnPcPy). The ZnPcPy system facilitates energy transfer from 16 covalently linked pyrene (Py) donor chromoph... Read More about Covalently linked pyrene antennas for optically dense yet aggregation-resistant light-harvesting systems.

Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy (2023)
Journal Article
Alanazi, F., Eggeman, A. S., Stavrou, K., Danos, A., Monkman, A. P., & Mendis, B. G. (2023). Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy. Journal of Physical Chemistry Letters, 14(36), 8183-8190. https://doi.org/10.1021/acs.jpclett.3c01344

Structural disorder in molecular crystals is a fundamental limitation for achieving high charge carrier mobilities. Quantifying and uncovering the mechanistic origins of disorder are, however, extremely challenging. Here we use variable coherence tra... Read More about Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy.

Azaborine as a Versatile Weak Donor for Thermally Activated Delayed Fluorescence (2023)
Journal Article
Sudhakar, P., Kuila, S., Stavrou, K., Danos, A., Slawin, A. M., Monkman, A., & Zysman-Colman, E. (2023). Azaborine as a Versatile Weak Donor for Thermally Activated Delayed Fluorescence. ACS Applied Materials and Interfaces, 15(21), 25806-25818. https://doi.org/10.1021/acsami.3c05409

Extensive research has been devoted to the development of thermally activated delayed fluorescence emitters, especially those showing pure-blue emission for use in lighting and fullcolor display applications. Towards that goal, herein we report a nov... Read More about Azaborine as a Versatile Weak Donor for Thermally Activated Delayed Fluorescence.

Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence (2023)
Journal Article
Paredis, S., Cardeynaels, T., Kuila, S., Deckers, J., Van Landeghem, M., Vandewal, K., …Maes, W. (2023). Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence. Chemistry - A European Journal, https://doi.org/10.1002/chem.202301369

Metal-free organic emitters that display solution-phase room temperature phosphorescence (sRTP) remain exceedingly rare. Here, we investigate the structural and photophysical properties that support sRTP by comparing a recently reported sRTP compound... Read More about Balanced Energy Gaps as a Key Design Rule for Solution‐Phase Organic Room Temperature Phosphorescence.

Donor, Acceptor, and Molecular Charge Transfer Emission All in One Molecule (2023)
Journal Article
Franca, L. G., Danos, A., & Monkman, A. (2023). Donor, Acceptor, and Molecular Charge Transfer Emission All in One Molecule. Journal of Physical Chemistry Letters, 14(11), 2764-2771. https://doi.org/10.1021/acs.jpclett.2c03925

The molecular photophysics in the thermally activated delayed fluorescence (TADF) spiro-acridine–anthracenone compound, ACRSA, is dominated by the rigid orthogonal spirocarbon bridging bond between the donor and acceptor. This critically decouples th... Read More about Donor, Acceptor, and Molecular Charge Transfer Emission All in One Molecule.

Rupturing aromaticity by periphery overcrowding (2023)
Journal Article
Saha, P. K., Mallick, A., Turley, A. T., Bismillah, A. N., Danos, A., Monkman, A. P., …McGonigal, P. R. (2023). Rupturing aromaticity by periphery overcrowding. Nature Chemistry, 15(4), 516-525. https://doi.org/10.1038/s41557-023-01149-6

The balance between strain relief and aromatic stabilization dictates the form and function of non-planar π-aromatics. Overcrowded systems are known to undergo geometric deformations, but the energetically favourable π-electron delocalization of thei... Read More about Rupturing aromaticity by periphery overcrowding.

Rational Molecular Design Enables Efficient Blue TADF−OLEDs with Flexible Graphene Substrate (2022)
Journal Article
Sharif, P., Alemdar, E., Ozturk, S., Caylan, O., Haciefendioglu, T., Buke, G., …Oral, A. (2022). Rational Molecular Design Enables Efficient Blue TADF−OLEDs with Flexible Graphene Substrate. Advanced Functional Materials, 32(47), Article 2207324. https://doi.org/10.1002/adfm.202207324

Observation of thermally activated delayed fluorescence (TADF) in conjugated systems redefined the molecular design approach to realize highly efficient organic light emitting diodes (OLEDs) in the early 2010s. Enabling effective reverse intersystem... Read More about Rational Molecular Design Enables Efficient Blue TADF−OLEDs with Flexible Graphene Substrate.

Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt? (2022)
Journal Article
Hempe, M., Kukhta, N. A., Danos, A., Batsanov, A. S., Monkman, A. P., & Bryce, M. R. (2022). Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt?. Journal of Physical Chemistry Letters, 13(35), 8221-8227. https://doi.org/10.1021/acs.jpclett.2c00907

Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials.... Read More about Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt?.

Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems (2022)
Journal Article
Kelly, D., Gomes Franca, L., Stavrou, K., Danos, A., & Monkman, A. P. (2022). Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems. Journal of Physical Chemistry Letters, 13(30), 6981-6986. https://doi.org/10.1021/acs.jpclett.2c01864

Donor–acceptor (D–A) thermally activated delayed fluorescence (TADF) molecules are exquisitely sensitive to D–A dihedral angle. Although commonly simplified to an average value, these D–A angles nonetheless exist as distributions across the individua... Read More about Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems.

Novel D–A chromophores with condensed 1,2,4-triazine system simultaneously display thermally activated delayed fluorescence and crystallization-induced phosphorescence (2022)
Journal Article
Maggiore, A., Tan, X., Brosseau, A., Danos, A., Miomandre, F., Monkman, A. P., …Clavier, G. (2022). Novel D–A chromophores with condensed 1,2,4-triazine system simultaneously display thermally activated delayed fluorescence and crystallization-induced phosphorescence. Physical Chemistry Chemical Physics, 24(29), 17770-17781. https://doi.org/10.1039/d2cp00777k

Control of photophysical properties is crucial for the continued development of electroluminescent devices and luminescent materials. Preparation and study of original molecules uncovers design rules towards efficient materials and devices. Here we h... Read More about Novel D–A chromophores with condensed 1,2,4-triazine system simultaneously display thermally activated delayed fluorescence and crystallization-induced phosphorescence.

Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs (2022)
Journal Article
Stavrou, K., Madayanad Suresh, S., Hall, D., Danos, A., Kukhta, N. A., Slawin, A. M., …Zysman‐Colman, E. (2022). Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs. Advanced Optical Materials, 10(17), Article 2200688. https://doi.org/10.1002/adom.202200688

Developing high-efficiency purely organic blue organic light-emitting diodes (OLEDs) that meet the stringent industry standards is a major current research challenge. Hyperfluorescent device approaches achieve in large measure the desired high perfor... Read More about Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs.

Effects of donor position and multiple charge transfer pathways in asymmetric pyridyl-sulfonyl TADF emitters (2022)
Journal Article
Haykir, G., Aydemir, M., Tekin, A., Tekin, E., Danos, A., Yuksel, F., …Turksoy, F. (2022). Effects of donor position and multiple charge transfer pathways in asymmetric pyridyl-sulfonyl TADF emitters. Materials Today Communications, 31, Article 103550. https://doi.org/10.1016/j.mtcomm.2022.103550

We have designed and synthesized a pair of highly asymmetric D-aA-D′ type pyridyl-sulfonyl based isomers comprising phenothiazine (PTZ) and carbazole (Cz) donor units, which are able to emit thermally activated delayed fluorescence. PTZ-pS4-Py-2Cz an... Read More about Effects of donor position and multiple charge transfer pathways in asymmetric pyridyl-sulfonyl TADF emitters.

Extended Conjugation Attenuates the Quenching of Aggregation-Induced Emitters by Photocyclization Pathways (2022)
Journal Article
Turley, A., Saha, P., Danos, A., Bismillah, A., Monkman, A., Yufit, D., …McGonigal, P. (2022). Extended Conjugation Attenuates the Quenching of Aggregation-Induced Emitters by Photocyclization Pathways. Angewandte Chemie International Edition, 61(24), Article e202202193. https://doi.org/10.1002/anie.202202193

Herein, we expose how the antagonistic relationship between solid-state luminescence and photocyclization of oligoaryl alkenes chromophores is modulated by the conjugation length of their alkenyl backbones. Heptaaryl cycloheptatriene molecular rotors... Read More about Extended Conjugation Attenuates the Quenching of Aggregation-Induced Emitters by Photocyclization Pathways.

The Effect of Imide Substituents on the Excited State Properties of Perylene Diimide Derivatives (2022)
Journal Article
Aksoy, E., Danos, A., Li, C., Monkman, A., & Varlikli, C. (2022). The Effect of Imide Substituents on the Excited State Properties of Perylene Diimide Derivatives. Turkish journal of science and technology, 17(1), 11-21. https://doi.org/10.55525/tjst.952823

Solid state optical properties of fluorescent materials are important for many photonic devices such as organic light emitting diodes, frequency down-converters or luminescent solar concentrators. Perylene diimides (PDIs) represent one of the most po... Read More about The Effect of Imide Substituents on the Excited State Properties of Perylene Diimide Derivatives.

Determining non-radiative decay rates in TADF compounds using coupled transient and steady state optical data (2022)
Journal Article
Sem, S., Jenatsch, S., Stavrou, K., Danos, A., Monkman, A. P., & Ruhstaller, B. (2022). Determining non-radiative decay rates in TADF compounds using coupled transient and steady state optical data. Journal of Materials Chemistry C Materials for optical and electronic devices, 10(12), 4878-4885. https://doi.org/10.1039/d1tc05594a

Thermally-activated delayed fluorescence (TADF) compounds are promising materials used in emissive layers of organic light-emitting diodes (OLEDs). Their main benefit is that they allow the internal quantum efficiency of the OLED to reach up to 100%... Read More about Determining non-radiative decay rates in TADF compounds using coupled transient and steady state optical data.

Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units (2022)
Journal Article
Hall, D., Stavrou, K., Duda, E., Danos, A., Bagnich, S., Warriner, S., …Zysman-Colman, E. (2022). Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units. Materials Horizons, 9(3), 1068-1080. https://doi.org/10.1039/d1mh01383a

In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms. Based on an in silico design, the compound DiICzMes4... Read More about Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units.

Bridge control of photophysical properties in benzothiazole-phenoxazine emitters – from thermally activated delayed fluorescence to room temperature phosphorescence (2022)
Journal Article
Paredis, S., Cardeynaels, T., Deckers, J., Danos, A., Vanderzande, D., Monkman, A. P., …Maes, W. (2022). Bridge control of photophysical properties in benzothiazole-phenoxazine emitters – from thermally activated delayed fluorescence to room temperature phosphorescence. Journal of Materials Chemistry C Materials for optical and electronic devices, 10(12), 4775-4784. https://doi.org/10.1039/d1tc04885f

The bridging phenyl group in a fluorescent phenoxazine-benzothiazole donor–acceptor dyad is replaced by either a naphthalene or a thiophene moiety to probe the influence of a more extended conjugated system or the presence of a sulfur-containing hete... Read More about Bridge control of photophysical properties in benzothiazole-phenoxazine emitters – from thermally activated delayed fluorescence to room temperature phosphorescence.

Spiro donor–acceptor TADF emitters: naked TADF free from inhomogeneity caused by donor acceptor bridge bond disorder. Fast rISC and invariant photophysics in solid state hosts (2022)
Journal Article
Gomes Franca, L., Danos, A., & Monkman, A. (2022). Spiro donor–acceptor TADF emitters: naked TADF free from inhomogeneity caused by donor acceptor bridge bond disorder. Fast rISC and invariant photophysics in solid state hosts. Journal of Materials Chemistry C Materials for optical and electronic devices, 10(4), 1313-1325. https://doi.org/10.1039/d1tc04484b

We have studied the thermally activated delayed fluorescence (TADF) properties of the spiro-bridged donor–acceptor molecule, 10-phenyl-10H,10′H-spiro[acridine-9,9-anthracen]-10′-one, (ACRSA) in guest–host films and used it as a probe to explore the d... Read More about Spiro donor–acceptor TADF emitters: naked TADF free from inhomogeneity caused by donor acceptor bridge bond disorder. Fast rISC and invariant photophysics in solid state hosts.

Not the Sum of their Parts: Understanding Multi-Donor Interactions in Symmetric and Asymmetric TADF Emitters (2021)
Journal Article
Danos, A., Gudeika, D., Kukhta, N., Lygaitis, R., Colella, M., Higginbotham, H., …Monkman, A. P. (2022). Not the Sum of their Parts: Understanding Multi-Donor Interactions in Symmetric and Asymmetric TADF Emitters. Journal of Materials Chemistry C Materials for optical and electronic devices, 10(12), 4737-4747. https://doi.org/10.1039/d1tc04171a

A pair of thermally activated delayed fluorescence (TADF) emitters with symmetric and asymmetric D-A-D structure are investigated. Despite displaying near-identical photoluminescence spectrum and quantum yields, the symmetric material possesses signi... Read More about Not the Sum of their Parts: Understanding Multi-Donor Interactions in Symmetric and Asymmetric TADF Emitters.

Effects of asymmetric acceptor and donor positioning in deep blue pyridyl-sulfonyl based TADF emitters (2021)
Journal Article
Haykir, G., Aydemir, M., Danos, A., Gumus, S., Hizal, G., Monkman, A. P., & Turksoy, F. (2021). Effects of asymmetric acceptor and donor positioning in deep blue pyridyl-sulfonyl based TADF emitters. Dyes and Pigments, 194, Article 109579. https://doi.org/10.1016/j.dyepig.2021.109579

In this work, we report synthesis and photophysical properties of deep-blue emitting donor-acceptor (D-A) and donor-acceptor-donor (D-A-D) thermally activated delayed fluorescence (TADF) molecules, where the molecules designed using carbazole as a do... Read More about Effects of asymmetric acceptor and donor positioning in deep blue pyridyl-sulfonyl based TADF emitters.

Silylethynyl Substitution for Preventing Aggregate Formation in Perylene Diimides (2021)
Journal Article
Aksoy, E., Danos, A., Li, C., Monkman, A. P., & Varlikli, C. (2021). Silylethynyl Substitution for Preventing Aggregate Formation in Perylene Diimides. Journal of Physical Chemistry C, 125(23), 13041-13049. https://doi.org/10.1021/acs.jpcc.1c03131

Ethynylene-bridged perylene diimides (PDIs) with different sized silane groups have been synthesized as a steric blocking group to prevent the formation of non-radiative trap sites, for example, strong H-aggregates and other dimers or excimers. Excit... Read More about Silylethynyl Substitution for Preventing Aggregate Formation in Perylene Diimides.

Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials (2021)
Journal Article
Hempe, M., Kukhta, N. A., Danos, A., Fox, M. A., Batsanov, A. S., Monkman, A. P., & Bryce, M. R. (2021). Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials. Chemistry of Materials, 33(9), 3066-3080. https://doi.org/10.1021/acs.chemmater.0c03783

We investigate a series of D–A molecules consisting of spiro[acridan-9,9′-fluorene] as the donor and 2-phenylenepyrimidine as the acceptor. In two of the materials, a spiro center effectively electronically isolates the D unit from (consequently) opt... Read More about Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials.

Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible? (2021)
Journal Article
Haase, N., Danos, A., Pflumm, C., Stachelek, P., Brütting, W., & Monkman, A. P. (2021). Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible?. Materials Horizons, 8(6), 1805-1815. https://doi.org/10.1039/d0mh01666g

Seemingly not, but for unexpected reasons. Combining the triplet harvesting properties of TADF materials with the fast emission rates and colour purity of fluorescent emitters is attractive for developing high performance OLEDs. In this “hyperfluores... Read More about Are the Rates of Dexter Transfer in TADF Hyperfluorescence Systems Optically Accessible?.

Difluorodithieno[3,2-a:2′,3′-c]phenazine as a strong acceptor for materials displaying thermally activated delayed fluorescence or room temperature phosphorescence (2021)
Journal Article
Cardeynaels, T., Paredis, S., Danos, A., Harrison, A., Deckers, J., Brebels, S., …Maes, W. (2021). Difluorodithieno[3,2-a:2′,3′-c]phenazine as a strong acceptor for materials displaying thermally activated delayed fluorescence or room temperature phosphorescence. Dyes and Pigments, 190, https://doi.org/10.1016/j.dyepig.2021.109301

A novel strong electron-acceptor unit, 9,10-difluorodithieno[3,2-a:2′,3′-c]phenazine (DTPz), is synthesized and applied in the design of two donor-acceptor type emitters displaying long-lived delayed emission. Using either 9,9-dimethyl-9,10-dihydroac... Read More about Difluorodithieno[3,2-a:2′,3′-c]phenazine as a strong acceptor for materials displaying thermally activated delayed fluorescence or room temperature phosphorescence.

Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials (2021)
Journal Article
Wright, I. A., Danos, A., Montanaro, S., Batsanov, A. S., Monkman, A. P., & Bryce, M. R. (2021). Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials. Chemistry - A European Journal, 27(21), 6545-6556. https://doi.org/10.1002/chem.202100036

A series of four heterocyclic dimers has been synthesized, with twisted geometries imposed across the central linking bond by ortho‐alkoxy chains. These include two isomeric bicarbazoles, a bis(dibenzothiophene‐S,S‐dioxide) and a bis(thioxanthene‐S,S... Read More about Conformational Dependence of Triplet Energies in Rotationally Hindered N‐ and S‐Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials.

Hot Vibrational States in a High-Performance Multiple Resonance Emitter and the Effect of Excimer Quenching on Organic Light-Emitting Diodes (2021)
Journal Article
Stavrou, K., Danos, A., Hama, T., Hatakeyama, T., & Monkman, A. (2021). Hot Vibrational States in a High-Performance Multiple Resonance Emitter and the Effect of Excimer Quenching on Organic Light-Emitting Diodes. ACS Applied Materials and Interfaces, 13(7), 8643-8655. https://doi.org/10.1021/acsami.0c20619

The photophysics of multiple resonance thermally activated delayed fluorescence molecule ν-DABNA is described. We show coupling of a 285 cm–1 stretching/scissoring vibrational mode of peripheral phenyl rings to the S1 state, which dictates the ultima... Read More about Hot Vibrational States in a High-Performance Multiple Resonance Emitter and the Effect of Excimer Quenching on Organic Light-Emitting Diodes.

The Critical Role of nπ* States in the Photophysics and Thermally Activated Delayed Fluorescence of Spiro Acridine-Anthracenone (2021)
Journal Article
Gomes Franca, L., Long, Y., Li, C., Danos, A., & Monkman, A. (2021). The Critical Role of nπ* States in the Photophysics and Thermally Activated Delayed Fluorescence of Spiro Acridine-Anthracenone. Journal of Physical Chemistry Letters, 12(5), 1490-1500. https://doi.org/10.1021/acs.jpclett.0c03314

The molecular photophysics and thermally activated delayed fluorescence (TADF) in spiro compounds are distinct because of the rigid orthogonal C–C bridging bond between donor and acceptor. The photophysics is found to be highly complex, with unpreced... Read More about The Critical Role of nπ* States in the Photophysics and Thermally Activated Delayed Fluorescence of Spiro Acridine-Anthracenone.

Exploiting trifluoromethyl substituents for tuning orbital character of singlet and triplet states to increase the rate of thermally activated delayed fluorescence (2020)
Journal Article
Ward, J. S., Danos, A., Stachelek, P., Fox, M. A., Batsanov, A. S., Monkman, A. P., & Bryce, M. R. (2020). Exploiting trifluoromethyl substituents for tuning orbital character of singlet and triplet states to increase the rate of thermally activated delayed fluorescence. Materials Chemistry Frontiers, 4(12), https://doi.org/10.1039/d0qm00429d

Benzo[1,2-b:4,5-b']dithiophene as a weak donor component for push-pull materials displaying thermally activated delayed fluorescence or room temperature phosphorescence (2020)
Journal Article
Cardeynaels, T., Paredis, S., Danos, A., Vanderzande, D., Monkman, A. P., Champagne, B., & Maes, W. (2021). Benzo[1,2-b:4,5-b']dithiophene as a weak donor component for push-pull materials displaying thermally activated delayed fluorescence or room temperature phosphorescence. Dyes and Pigments, 186, https://doi.org/10.1016/j.dyepig.2020.109022

In the search for high-performance donor-acceptor type organic compounds displaying thermally activated delayed fluorescence (TADF), triisopropylsilyl-protected benzo[1,2-b:4,5-b']dithiophene (BDT-TIPS) is presented as a novel donor component in comb... Read More about Benzo[1,2-b:4,5-b']dithiophene as a weak donor component for push-pull materials displaying thermally activated delayed fluorescence or room temperature phosphorescence.

Suppressing Dimer Formation by Increasing Conformational Freedom in Multi-Carbazole Thermally Activated Delayed Fluorescence Emitters (2020)
Journal Article
Salah, L., Etherington, M., Shuaib, A., Danos, A., Nazeer, A., Ghazal, B., …Makhseed, S. (2021). Suppressing Dimer Formation by Increasing Conformational Freedom in Multi-Carbazole Thermally Activated Delayed Fluorescence Emitters. Journal of Materials Chemistry C Materials for optical and electronic devices, 9(1), 189-198. https://doi.org/10.1039/d0tc04222f

Ideal emitters for organic light-emitting diodes (OLEDs) are capable of efficiently harvesting non-emissive triplet states, have high colour stabilities, and possess high photoluminescence quantum yields (PLQYs). Maintaining colour stability and PLQY... Read More about Suppressing Dimer Formation by Increasing Conformational Freedom in Multi-Carbazole Thermally Activated Delayed Fluorescence Emitters.

Navigating CIE Space for Efficient TADF Downconversion WOLEDs (2020)
Journal Article
Aksoy, E., Danos, A., Varlikli, C., & Monkman, A. P. (2020). Navigating CIE Space for Efficient TADF Downconversion WOLEDs. Dyes and Pigments, 183, Article 108707. https://doi.org/10.1016/j.dyepig.2020.108707

High efficiency orange and green emitting perylene dyes have been synthesised and dispersed in an inert polymer host to form an optical downconversion layer. To avoid dye aggregation and allow controlled colour tuning, this layer was deposited in mul... Read More about Navigating CIE Space for Efficient TADF Downconversion WOLEDs.

Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield (2020)
Journal Article
Turley, A., Danos, A., Prlj, A., Monkman, A., Curchod, B., McGonigal, P., & Etherington, M. (2020). Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield. Chemical Science, 11(27), 6990-6995. https://doi.org/10.1039/d0sc02460k

Charge transfer in organic fluorophores is a fundamental photophysical process that can be either beneficial, e.g., facilitating thermally activated delayed fluorescence, or detrimental, e.g., mediating emission quenching. N-Alkylation is shown to pr... Read More about Modulation of Charge Transfer by N-Alkylation to Control Photoluminescence Energy and Quantum Yield.

Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System (2020)
Journal Article
Long, Y., Mamada, M., Li, C., dos Santos, P. L., Colella, M., Danos, A., …Monkman, A. (2020). Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System. Journal of Physical Chemistry Letters, 11(9), 3305-3312. https://doi.org/10.1021/acs.jpclett.0c00498

We describe the photophysical processes that give rise to thermally activated delayed fluorescence in the excited state intramolecular proton transfer (ESIPT) molecule, triquinolonobenzene (TQB). Using transient absorption and time-resolved photolumi... Read More about Excited State Dynamics of Thermally Activated Delayed Fluorescence from an Excited State Intramolecular Proton Transfer System.

Balancing charge-transfer strength and triplet states for deep-blue thermally activated delayed fluorescence with an unconventional electron rich dibenzothiophene acceptor (2019)
Journal Article
Huang, R., Kukhta, N., Ward, J., Danos, A., Batsanov, A., Bryce, M., & Dias, F. (2019). Balancing charge-transfer strength and triplet states for deep-blue thermally activated delayed fluorescence with an unconventional electron rich dibenzothiophene acceptor. Journal of Materials Chemistry C Materials for optical and electronic devices, 7(42), 13224-13234. https://doi.org/10.1039/c9tc02175b

Manipulation of the emission properties of deep-blue emitters exhibiting thermally activated delayed fluorescence (TADF) through molecular design is challenging. We present an effective strategy to probe deeper into the role of localized (LE) and cha... Read More about Balancing charge-transfer strength and triplet states for deep-blue thermally activated delayed fluorescence with an unconventional electron rich dibenzothiophene acceptor.

Molecular Design Strategies for Color Tuning of Blue TADF Emitters (2019)
Journal Article
Stachelek, P., Ward, J. S., dos Santos, P. L., Danos, A., Colella, M., Haase, N., …Monkman, A. P. (2019). Molecular Design Strategies for Color Tuning of Blue TADF Emitters. ACS Applied Materials and Interfaces, 11(30), 27125-27133. https://doi.org/10.1021/acsami.9b06364

New thermally activated delayed fluorescence (TADF) blue emitter molecules based on the known donor−acceptor−donor (D−A−D)- type TADF molecule, 2,7-bis(9,9-dimethylacridin-10-yl)-9,9-dimethylthioxanthene- S,S-dioxide (DDMA-TXO2), are reported. The mo... Read More about Molecular Design Strategies for Color Tuning of Blue TADF Emitters.

Revealing Resonance Effects and Intramolecular Dipole Interactions in the Positional Isomers of Benzonitrile-Core Thermally Activated Delayed Fluorescence Materials (2019)
Journal Article
Kukhta, N., Higginbotham, H., Matulaitis, T., Danos, A., Bismillah, A., Haase, N., …Monkman, A. (2019). Revealing Resonance Effects and Intramolecular Dipole Interactions in the Positional Isomers of Benzonitrile-Core Thermally Activated Delayed Fluorescence Materials. Journal of Materials Chemistry C Materials for optical and electronic devices, 7(30), 9184-9194. https://doi.org/10.1039/c9tc02742d

We report on the properties of the three positional isomers of (2,7-di-tert-butyl-9,9-dimethylacridin-10(9H)-yl)benzonitrile, which are found to have comparable donor steric environments and donor–acceptor dihedral angles. An unexpected intramolecula... Read More about Revealing Resonance Effects and Intramolecular Dipole Interactions in the Positional Isomers of Benzonitrile-Core Thermally Activated Delayed Fluorescence Materials.

Identifying the Factors That Lead to PLQY Enhancement in Diluted TADF Exciplexes Based on Carbazole Donors (2019)
Journal Article
Colella, M., Danos, A., & Monkman, A. P. (2019). Identifying the Factors That Lead to PLQY Enhancement in Diluted TADF Exciplexes Based on Carbazole Donors. Journal of Physical Chemistry C, 123(28), 17318-17324. https://doi.org/10.1021/acs.jpcc.9b03538

Here we compare the effects of solid-state dilution on the photophysical and electrical performance of three TADF exciplexes based on carbazole containing donors with a high-performance acceptor PO-T2T. We observe intrinsically different photophysica... Read More about Identifying the Factors That Lead to PLQY Enhancement in Diluted TADF Exciplexes Based on Carbazole Donors.

Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters (2019)
Journal Article
De Sa Pereira, D., Menelaou, C., Danos, A., Marian, C. M., & Monkman, A. P. (2019). Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters. Journal of Physical Chemistry Letters, 10(12), 3205-3211. https://doi.org/10.1021/acs.jpclett.9b00999

Solid-state electroabsorption is demonstrated as a powerful tool to probe the charge-transfer (CT) character and state mixing in the low energy optical transitions of two structurally similar thermally-activated delayed fluorescent (TADF) materials w... Read More about Electroabsorption Spectroscopy as a Tool to Probe Charge-Transfer and State Mixing in Thermally-Activated Delayed Fluorescence Emitters.

Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials (2019)
Journal Article
Etherington, M. K., Kukhta, N. A., Higginbotham, H. F., Danos, A., Bismillah, A. N., Graves, D. R., …Monkman, A. P. (2019). Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials. Journal of Physical Chemistry C, 123(17), 11109-11117. https://doi.org/10.1021/acs.jpcc.9b01458

We expose significant changes in emission color of carbazole-based thermally activated delayed fluorescence (TADF) emitters that arise through the presence of persistent dimer states in thin films and organic light-emitting diodes(OLEDs). Direct phot... Read More about Persistent Dimer Emission in Thermally Activated Delayed Fluorescence Materials.

Less Is More: Dilution Enhances Optical and Electrical Performance of a TADF Exciplex (2019)
Journal Article
Colella, M., Danos, A., & Monkman, A. P. (2019). Less Is More: Dilution Enhances Optical and Electrical Performance of a TADF Exciplex. Journal of Physical Chemistry Letters, 10(4), 793-798. https://doi.org/10.1021/acs.jpclett.8b03646

A surprising yet highly practical approach to improve the performance of a TADF exciplex blend is reported. Using the TSBPA donor and PO-T2T acceptor to form an exciplex, we are able to blue shift the emission, increase PLQY from 58 to 80%, and incre... Read More about Less Is More: Dilution Enhances Optical and Electrical Performance of a TADF Exciplex.

Kinetic Modeling of Transient Photoluminescence from Thermally Activated Delayed Fluorescence (2018)
Journal Article
Haase, N., Danos, A., Pflumm, C., Morherr, A., Stachelek, P., Mekic, A., …Monkman, A. P. (2018). Kinetic Modeling of Transient Photoluminescence from Thermally Activated Delayed Fluorescence. Journal of Physical Chemistry C, 122(51), 29173-29179. https://doi.org/10.1021/acs.jpcc.8b11020

A simplified state model and associated rate equations are used to extract the reverse intersystem crossing and other key rate constants from transient photoluminescence measurements of two high performance thermally activated delayed fluorescence ma... Read More about Kinetic Modeling of Transient Photoluminescence from Thermally Activated Delayed Fluorescence.