Kleitos Stavrou's Outputs (19)

Diffusion‐Free Intramolecular Triplet–Triplet Annihilation Contributes to the Enhanced Exciton Utilization in OLEDs (2024)
Journal Article
Mattiello, S., Danos, A., Stavrou, K., Ronchi, A., Baranovski, R., Florenzano, D., Meinardi, F., Beverina, L., Monkman, A., & Monguzzi, A. (in press). Diffusion‐Free Intramolecular Triplet–Triplet Annihilation Contributes to the Enhanced Exciton Utilization in OLEDs. Advanced Optical Materials, https://doi.org/10.1002/adom.202401597

Triplet–triplet annihilation (TTA), or triplet fusion, is a biexcitonic process in which two triplet‐excited molecules can combine their energy to promote one into an excited singlet state. To alleviate the dependence of the TTA rate and yield on tri... Read More about Diffusion‐Free Intramolecular Triplet–Triplet Annihilation Contributes to the Enhanced Exciton Utilization in OLEDs.

Aryl-Substituted Acridine Donor Derivatives Modulate the Transition Dipole Moment Orientation and Exciton Harvesting Properties of Donor–Acceptor TADF Emitters (2024)
Journal Article
Crovini, E., Stavrou, K., Sahay, P., Nguyễn, B., Comerford, T., Warriner, S., Brütting, W., Monkman, A., & Zysman-Colman, E. (2024). Aryl-Substituted Acridine Donor Derivatives Modulate the Transition Dipole Moment Orientation and Exciton Harvesting Properties of Donor–Acceptor TADF Emitters. Journal of Physical Chemistry C, 128(34), 14429-14441. https://doi.org/10.1021/acs.jpcc.4c03344

Thermally activated delayed fluorescence (TADF) compounds are highly attractive as sensitizing and emitting materials for organic light-emitting diodes (OLEDs). The efficiency of the OLED depends on multiple parameters, most of which rely on the prop... Read More about Aryl-Substituted Acridine Donor Derivatives Modulate the Transition Dipole Moment Orientation and Exciton Harvesting Properties of Donor–Acceptor TADF Emitters.

Exciplex, Not Heavy-Atom Effect, Controls the Triplet Dynamics of a Series of Sulfur-Containing Thermally Activated Delayed Fluorescence Molecules (2024)
Journal Article
Öner, S., Kuila, S., Stavrou, K., Danos, A., Fox, M. A., Monkman, A. P., & Bryce, M. R. (2024). Exciplex, Not Heavy-Atom Effect, Controls the Triplet Dynamics of a Series of Sulfur-Containing Thermally Activated Delayed Fluorescence Molecules. Chemistry of Materials, 36(15), 7135-7150. https://doi.org/10.1021/acs.chemmater.4c00850

The efficiency of thermally activated delayed fluorescence (TADF) in organic materials relies on rapid intersystem crossing rates and fast conversion of triplet (T) excitons into a singlet (S) state. Heavy atoms such as sulfur or selenium are now fre... Read More about Exciplex, Not Heavy-Atom Effect, Controls the Triplet Dynamics of a Series of Sulfur-Containing Thermally Activated Delayed Fluorescence Molecules.

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.

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.

Rational design of dibenzo[a,c]phenazine-derived isomeric thermally activated delayed fluorescence luminophores for efficient orange-red organic light-emitting diodes (2023)
Journal Article
Ye, H., Yang, J., Stavrou, K., Li, M., Liu, F., Li, F., …Monkman, A. P. (2023). Rational design of dibenzo[a,c]phenazine-derived isomeric thermally activated delayed fluorescence luminophores for efficient orange-red organic light-emitting diodes. Dyes and Pigments, 219, Article 111568. https://doi.org/10.1016/j.dyepig.2023.111568

It is an immense challenge to develop efficient long-wavelength (orange-to-red) thermally activated delayed fluorescence (TADF) materials due to the increasing nonradiative decay rates following the energy-gap law. Herein, two pairs of asymmetric iso... Read More about Rational design of dibenzo[a,c]phenazine-derived isomeric thermally activated delayed fluorescence luminophores for efficient orange-red organic light-emitting diodes.

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.

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.

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.

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.

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.

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.

Investigation of Intramolecular Through-Space Charge-Transfer States in Donor–Acceptor Charge-Transfer Systems (2021)
Journal Article
Kumar, S., Gomes Franca, L., Stavrou, K., Crovini, E., Cordes, D. B., Slawin, A. M., …Zysman-Colman, E. (2021). Investigation of Intramolecular Through-Space Charge-Transfer States in Donor–Acceptor Charge-Transfer Systems. Journal of Physical Chemistry Letters, 12(11), https://doi.org/10.1021/acs.jpclett.1c00265

Commonly, thermally activated delayed fluorescence (TADF) emitters present a twisted donor–acceptor structure. Here, electronic communication is mediated through-bond via π-conjugation between donor and acceptor groups. A second class of TADF emitter... Read More about Investigation of Intramolecular Through-Space Charge-Transfer States in Donor–Acceptor Charge-Transfer Systems.

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.

Photophysics of TADF guest-host systems: introducing the idea of hosting potential (2020)
Journal Article
Stavrou, K., Gomes Franca, L., & Monkman, A. P. (2020). Photophysics of TADF guest-host systems: introducing the idea of hosting potential. ACS Applied Electronic Materials, 2(9), 2868-2881. https://doi.org/10.1021/acsaelm.0c00514

The thermally activated delayed fluorescence (TADF) donor-acceptor (D-A) molecule, DMAC-TRZ, is used as a TADF emitter ‘probe’ to distinguish the environmental effects of a range of solid state host materials in guest-host systems. Using the guest’s... Read More about Photophysics of TADF guest-host systems: introducing the idea of hosting potential.