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.

Fine‐Tuning the Photophysics of Donor‐Acceptor (D‐A 3 ) Thermally Activated Delayed Fluorescence Emitters Using Isomerisation (2022)
Journal Article
L. dos Santos, P., de Sa Pereira, D., Eng, J., Ward, J. S., Bryce, M. R., Penfold, T. J., & Monkman, A. P. (2023). Fine‐Tuning the Photophysics of Donor‐Acceptor (D‐A 3 ) Thermally Activated Delayed Fluorescence Emitters Using Isomerisation. ChemPhotoChem, 7(2), Article e202200248. https://doi.org/10.1002/cptc.202200248

Here two D–A3 regioisomers, comprising three dibenzothiophene-S,S-dioxide acceptor units attached to a central triazatruxene core, are studied. Both molecules show thermally activated delayed fluorescence (TADF), however, the efficiency of the TADF m... Read More about Fine‐Tuning the Photophysics of Donor‐Acceptor (D‐A 3 ) Thermally Activated Delayed Fluorescence Emitters Using Isomerisation.

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?.

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.

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.

Dominant dimer emission provides colour stability for red thermally activated delayed fluorescence emitter (2022)
Journal Article
Cardeynaels, T., Etherington, M. K., Paredis, S., Batsanov, A. S., Deckers, J., Stavrou, K., …Maes, W. (2022). Dominant dimer emission provides colour stability for red thermally activated delayed fluorescence emitter. Journal of Materials Chemistry C Materials for optical and electronic devices, 10(15), https://doi.org/10.1039/d1tc04913e

Colour purity and stability in multi-donor thermally activated delayed fluorescence (TADF) emitters has significant implications for commercial organic light-emitting diode (OLED) design. The formation of emissive dimer states in the well-known 1,2,3... Read More about Dominant dimer emission provides colour stability for red thermally activated delayed fluorescence emitter.

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?.

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.

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.

Unusual dual-emissive heteroleptic iridium complexes incorporating TADF cyclometalating ligands (2020)
Journal Article
Benjamin, H., Zheng, Y., Kozhevnikov, V. N., Siddle, J. S., O'Driscoll, L. J., Fox, M. A., …Bryce, M. R. (2020). Unusual dual-emissive heteroleptic iridium complexes incorporating TADF cyclometalating ligands. Dalton Transactions, 49(7), 2190-2208. https://doi.org/10.1039/c9dt04672k

Five new neutral heteroleptic iridium(III) complexes IrL2(pic) (2–6) based on the archetypical blue emitter FIrpic have been synthesised. The cyclometallating ligands L are derived from 2-(2,6-F2-3-pyridyl)-4-mesitylpyridine (7), 2-(3-cyano-2,6-F2-ph... Read More about Unusual dual-emissive heteroleptic iridium complexes incorporating TADF cyclometalating ligands.

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.

Delayed Blue Fluorescence via Upper-triplet State Crossing from C-C Bonded Donor-Acceptor Charge-Transfer Molecules with Azatriangulene cores (2019)
Journal Article
Ward, J., Kukhta, N., Dos Santos, P., Congrave, D., Batsanov, A., Monkman, A., & Bryce, M. (2019). Delayed Blue Fluorescence via Upper-triplet State Crossing from C-C Bonded Donor-Acceptor Charge-Transfer Molecules with Azatriangulene cores. Chemistry of Materials, 31(17), 6684-6695. https://doi.org/10.1021/acs.chemmater.9b01184

We report the synthesis and structural and photophysical characterization of two series of molecules with functionalized azatriangulene electron donor cores and three pendant electron acceptor units. The presented donor and acceptor units are joined... Read More about Delayed Blue Fluorescence via Upper-triplet State Crossing from C-C Bonded Donor-Acceptor Charge-Transfer Molecules with Azatriangulene cores.

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.

Importance of Chromophore Rigidity on the Efficiency of Blue Thermally Activated Delayed Fluorescence Emitters (2018)
Journal Article
Kukhta, N. A., Batsanov, A. S., Bryce, M. R., & Monkman, A. P. (2018). Importance of Chromophore Rigidity on the Efficiency of Blue Thermally Activated Delayed Fluorescence Emitters. Journal of Physical Chemistry C, 122(50), 28564-28575. https://doi.org/10.1021/acs.jpcc.8b10867

Four new symmetrical donor–acceptor–donor (D–A–D)-type molecules are reported with diphenylamine (DPA) or 10,11-dihydro-5H-dibenz[b,f]azepine (Az) as electron donors and 9,9-dimethylthioxanthene-S,S-dioxide (TXO2) as the electron acceptor. The donors... Read More about Importance of Chromophore Rigidity on the Efficiency of Blue Thermally Activated Delayed Fluorescence Emitters.

Triazatruxene: A rigid central donor unit for a D-A3 thermally activated delayed fluorescence material exhibiting sub-microsecond reverse intersystem crossing and unity quantum yield via multiple singlet-triplet state pairs (2018)
Journal Article
dos Santos, P. L., Ward, J. S., Congrave, D. G., Batsanov, A. S., Eng, J., Stacey, J. E., …Bryce, M. R. (2018). Triazatruxene: A rigid central donor unit for a D-A3 thermally activated delayed fluorescence material exhibiting sub-microsecond reverse intersystem crossing and unity quantum yield via multiple singlet-triplet state pairs. Advanced Science, 5(6), Article 1700989. https://doi.org/10.1002/advs.201700989

By inverting the common structural motif of thermally activated delayed fluorescence materials to a rigid donor core and multiple peripheral acceptors, reverse intersystem crossing (rISC) rates are demonstrated in an organic material that enables uti... Read More about Triazatruxene: A rigid central donor unit for a D-A3 thermally activated delayed fluorescence material exhibiting sub-microsecond reverse intersystem crossing and unity quantum yield via multiple singlet-triplet state pairs.

Pyridylpyrazole N^N Ligands Combined with Sulfonyl-Functionalised Cyclometalating Ligands for Blue-Emitting Iridium(III) Complexes and Solution-Processable PhOLEDs (2017)
Journal Article
Benjamin, H., Fox, M. A., Batsanov, A. S., Al-Attar, H. A., Li, C., Ren, Z., …Bryce, M. R. (2017). Pyridylpyrazole N^N Ligands Combined with Sulfonyl-Functionalised Cyclometalating Ligands for Blue-Emitting Iridium(III) Complexes and Solution-Processable PhOLEDs. Dalton Transactions, 46, 10996-11007. https://doi.org/10.1039/c7dt02289a

A series of blue iridium(III) complexes (12–15) comprising sulfonyl-functionalised phenylpyridyl cyclometalating ligands and pyridylpyrazole N^N ligands are reported, with an X-ray crystal structure obtained for 12. The complexes are highly emissive... Read More about Pyridylpyrazole N^N Ligands Combined with Sulfonyl-Functionalised Cyclometalating Ligands for Blue-Emitting Iridium(III) Complexes and Solution-Processable PhOLEDs.

Photophysics of an Asymmetric Donor–Acceptor–Donor′ TADF Molecule and Reinterpretation of Aggregation-Induced TADF Emission in These Materials (2017)
Journal Article
Aydemir, M., Xu, S., Chen, C., Bryce, M. R., Chi, Z., & Monkman, A. P. (2017). Photophysics of an Asymmetric Donor–Acceptor–Donor′ TADF Molecule and Reinterpretation of Aggregation-Induced TADF Emission in These Materials. Journal of Physical Chemistry C, 121(33), 17764-17772. https://doi.org/10.1021/acs.jpcc.7b06299

We report an in-depth photophysical investigation of an asymmetric donor–acceptor–donor′ (D–A–D′) thermally activated delayed fluorescence (TADF) molecule (4-(9H-carbazol-9-yl)phenyl)(4-(10H-phenothiazin-10-yl)phenyl)sulfone and compare its photophys... Read More about Photophysics of an Asymmetric Donor–Acceptor–Donor′ TADF Molecule and Reinterpretation of Aggregation-Induced TADF Emission in These Materials.

Optical and Polarity Control of Donor–Acceptor Conformation and Their Charge-Transfer States in Thermally Activated Delayed-Fluorescence Molecules (2017)
Journal Article
dos Santos, P. L., Ward, J. S., Batsanov, A. S., Bryce, M. R., & Monkman, A. P. (2017). Optical and Polarity Control of Donor–Acceptor Conformation and Their Charge-Transfer States in Thermally Activated Delayed-Fluorescence Molecules. Journal of Physical Chemistry C, 121(30), 16462-16469. https://doi.org/10.1021/acs.jpcc.7b03672

This study reports two novel D–A–D molecules, 2,7-bis(phenothiazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DPT-TXO2) and 2,7-bis(1-methylphenothiazin-10-yl)-9,9-dimethylthioxanthene-S,S-dioxide (DMePT-TXO2), where the latter differs by only a me... Read More about Optical and Polarity Control of Donor–Acceptor Conformation and Their Charge-Transfer States in Thermally Activated Delayed-Fluorescence Molecules.