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.

Conformational, Host, and Vibrational Effects Giving Rise to Dynamic TADF Behavior in the Through-Space Charge Transfer, Triptycene Bridged Acridine-Triazine Donor Acceptor TADF Molecule TpAT-tFFO (2023)
Journal Article
Miranda-Salinas, H., Rodriguez-Serrano, A., Kaminski, J. M., Dinkelbach, F., Hiromichi, N., Kusakabe, Y., …Monkman, A. P. (2023). Conformational, Host, and Vibrational Effects Giving Rise to Dynamic TADF Behavior in the Through-Space Charge Transfer, Triptycene Bridged Acridine-Triazine Donor Acceptor TADF Molecule TpAT-tFFO. Journal of Physical Chemistry C, 127(18), 8607-8617. https://doi.org/10.1021/acs.jpcc.2c07529

We present a joint experimental and theoretical study of the through-space charge transfer (CT) TADF molecule TpAT-tFFO. The measured fluorescence has a singular Gaussian line shape but two decay components, coming from two distinct molecular CT conf... Read More about Conformational, Host, and Vibrational Effects Giving Rise to Dynamic TADF Behavior in the Through-Space Charge Transfer, Triptycene Bridged Acridine-Triazine Donor Acceptor TADF Molecule TpAT-tFFO.

Unexpected Quasi‐Axial Conformer in Thermally Activated Delayed Fluorescence DMAC‐TRZ, Pushing Green OLEDs to Blue (2023)
Journal Article
Stavrou, K., Franca, L. G., Böhmer, T., Duben, L. M., Marian, C. M., & Monkman, A. P. (2023). Unexpected Quasi‐Axial Conformer in Thermally Activated Delayed Fluorescence DMAC‐TRZ, Pushing Green OLEDs to Blue. Advanced Functional Materials, 33(25), Article 2300910. https://doi.org/10.1002/adfm.202300910

Hidden photophysics is elucidated in the very well-known thermally activated delayed fluorescence (TADF) emitter, DMAC-TRZ. A molecule that, based on its structure, is considered not to have more than one structural conformation. However, based on ex... Read More about Unexpected Quasi‐Axial Conformer in Thermally Activated Delayed Fluorescence DMAC‐TRZ, Pushing Green OLEDs to Blue.

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.

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.

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?.

Thermally Activated Delayed Fluorescence: Polarity, Rigidity, and Disorder in Condensed Phases (2022)
Journal Article
Phan Huu, D. A., Saseendran, S., Dhali, R., Gomes Franca, L., Stavrou, K., Monkman, A., & Painelli, A. (2022). Thermally Activated Delayed Fluorescence: Polarity, Rigidity, and Disorder in Condensed Phases. Journal of the American Chemical Society, 144(33), 15211 - 15222. https://doi.org/10.1021/jacs.2c05537

We present a detailed and comprehensive picture of the photophysics of thermally activated delayed fluorescence (TADF). The approach relies on a few-state model, parametrized ab initio on a prototypical TADF dye, that explicitly accounts for the nona... Read More about Thermally Activated Delayed Fluorescence: Polarity, Rigidity, and Disorder in Condensed Phases.

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.

Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films (2022)
Journal Article
Gomes Franca, L., dos Santos, P. L., Pander, P., Cabral, M. G., Cristiano, R., Cazati, T., …Eccher, J. (2022). Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films. ACS Applied Electronic Materials, 4(7), https://doi.org/10.1021/acsaelm.2c00432

Delayed fluorescence (DF) by triplet–triplet annihilation (TTA) is observed in solutions of a benzoperylene-imidoester mesogen that shows a hexagonal columnar mesophase at room temperature in the neat state. A similar benzoperylene-imide with a sligh... Read More about Delayed Fluorescence by Triplet–Triplet Annihilation from Columnar Liquid Crystal Films.

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.

Vibronic effects accelerate the intersystem crossing processes of the through-space charge transfer states in the triptycene bridged acridine–triazine donor–acceptor molecule TpAT-tFFO (2022)
Journal Article
Kaminski, J. M., Rodríguez-Serrano, A., Dinkelbach, F., Miranda-Salinas, H., Monkman, A. P., & Marian, C. M. (2022). Vibronic effects accelerate the intersystem crossing processes of the through-space charge transfer states in the triptycene bridged acridine–triazine donor–acceptor molecule TpAT-tFFO. Chemical Science, 13(23), https://doi.org/10.1039/d1sc07101g

Quantum chemical studies employing combined density functional and multireference configuration interaction methods suggest five excited electronic states to be involved in the prompt and delayed fluorescence emission of TpAT-tFFO. Three of them, a p... Read More about Vibronic effects accelerate the intersystem crossing processes of the through-space charge transfer states in the triptycene bridged acridine–triazine donor–acceptor molecule TpAT-tFFO.

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.

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.

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.