1
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Eng J, Rankine CD, Penfold TJ. The photochemistry of Rydberg-excited cyclobutanone: Photoinduced processes and ground state dynamics. J Chem Phys 2024; 160:154301. [PMID: 38619456 DOI: 10.1063/5.0203597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/28/2024] [Indexed: 04/16/2024] Open
Abstract
Owing to ring strain, cyclic ketones exhibit complex excited state dynamics with multiple competing photochemical channels active on the ultrafast timescale. While the excited state dynamics of cyclobutanone after π* ← n excitation into the lowest-energy excited singlet (S1) state has been extensively studied, the dynamics following 3s ← n excitation into the higher-lying singlet Rydberg (S2) state are less well understood. Herein, we employ fully quantum multiconfigurational time-dependent Hartree (MCTDH) simulations using a model Hamiltonian as well as "on-the-fly" trajectory-based surface-hopping dynamics (TSHD) simulations to study the relaxation dynamics of cyclobutanone following 3s ← n excitation and to predict the ultrafast electron diffraction scattering signature of these relaxation dynamics. Our MCTDH and TSHD simulations indicate that relaxation from the initially-populated singlet Rydberg (S2) state occurs on the timescale of a few hundreds of femtoseconds to a picosecond, consistent with the symmetry-forbidden nature of the state-to-state transition involved. There is no obvious involvement of excited triplet states within the timeframe of our simulations (<2 ps). After non-radiative relaxation to the electronic ground state (S0), vibrationally hot cyclobutanone has sufficient internal energy to form multiple fragmented products including C2H4 + CH2CO (C2; 20%) and C3H6 + CO (C3; 2.5%). We discuss the limitations of our MCTDH and TSHD simulations, how these may influence the excited state dynamics we observe, and-ultimately-the predictive power of the simulated experimental observable.
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Affiliation(s)
- J Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - C D Rankine
- Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - T J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
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2
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Pope T, Eng J, Monkman A, Penfold TJ. Spin-Vibronic Intersystem Crossing and Molecular Packing Effects in Heavy Atom Free Organic Phosphor. J Chem Theory Comput 2024; 20:1337-1346. [PMID: 38272840 PMCID: PMC10867843 DOI: 10.1021/acs.jctc.3c01220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/27/2024]
Abstract
We present a detailed investigation into the excited state properties of a planar D3h symmetric azatriangulenetrione, HTANGO, which has received significant interest due to its high solid-state phosphorescence quantum yield and therefore potential as an organic room temperature phosphorescent (ORTP) dye. Using a model linear vibronic coupling Hamiltonian in combination with quantum dynamics simulations, we observe that intersystem crossing (ISC) in HTANGO occurs with a rate of ∼1010 s-1, comparable to benzophenone, an archetypal molecule for fast ISC in heavy metal free molecules. Our simulations demonstrate that the mechanism for fast ISC is associated with the high density of excited triplet states which lie in close proximity to the lowest singlet states, offering multiple channels into the triplet manifold facilitating rapid population transfer. Finally, to rationalize the solid-state emission properties, we use quantum chemistry to investigate the excited state surfaces of the HTANGO dimer, highlighting the influence and importance of the rotational alignment between the two HTANGO molecules in the solid state and how this contributes to high phosphorescence quantum yield.
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Affiliation(s)
- Thomas Pope
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Julien Eng
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Andrew Monkman
- Department
of Physics, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Thomas J. Penfold
- Chemistry,
School of Natural and Environmental Sciences, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
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3
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Alkhudhayr EA, Sirbu D, Fsadni M, Vella B, Muhammad BT, Waddell PG, Probert MR, Penfold TJ, Hallam T, Gibson EA, Docampo P. Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells. ACS Appl Energy Mater 2023; 6:11573-11582. [PMID: 38037633 PMCID: PMC10685326 DOI: 10.1021/acsaem.3c01988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/13/2023] [Accepted: 10/23/2023] [Indexed: 12/02/2023]
Abstract
Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10-5 S cm-1 upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10-6 S cm-1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.
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Affiliation(s)
- Eman A.
A. Alkhudhayr
- Energy
Materials Laboratory, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- Department
of Physics, College of Science, King Faisal
University, Al Ahsa 31982, Saudi Arabia
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Dumitru Sirbu
- Physics,
School of Mathematics, Statistics and Physics, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Miriam Fsadni
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Benjamin Vella
- School
of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Bening T. Muhammad
- Energy
Materials Laboratory, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Paul G. Waddell
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Michael R. Probert
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Thomas J. Penfold
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Toby Hallam
- Physics,
School of Mathematics, Statistics and Physics, Newcastle University, Newcastle
upon Tyne NE1 7RU, U.K.
| | - Elizabeth A. Gibson
- Energy
Materials Laboratory, Newcastle University, Newcastle upon Tyne NE1
7RU, U.K.
- Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
- School
of Natural and Environmental Sciences, Bedson Building,Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
| | - Pablo Docampo
- School
of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
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4
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Watson L, Pope T, Jay RM, Banerjee A, Wernet P, Penfold TJ. A Δ-learning strategy for interpretation of spectroscopic observables. Struct Dyn 2023; 10:064101. [PMID: 37941993 PMCID: PMC10629969 DOI: 10.1063/4.0000215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/17/2023] [Indexed: 11/10/2023]
Abstract
Accurate computations of experimental observables are essential for interpreting the high information content held within x-ray spectra. However, for complicated systems this can be difficult, a challenge compounded when dynamics becomes important owing to the large number of calculations required to capture the time-evolving observable. While machine learning architectures have been shown to represent a promising approach for rapidly predicting spectral lineshapes, achieving simultaneously accurate and sufficiently comprehensive training data is challenging. Herein, we introduce Δ-learning for x-ray spectroscopy. Instead of directly learning the structure-spectrum relationship, the Δ-model learns the structure dependent difference between a higher and lower level of theory. Consequently, once developed these models can be used to translate spectral shapes obtained from lower levels of theory to mimic those corresponding to higher levels of theory. Ultimately, this achieves accurate simulations with a much reduced computational burden as only the lower level of theory is computed, while the model can instantaneously transform this to a spectrum equivalent to a higher level of theory. Our present model, demonstrated herein, learns the difference between TDDFT(BLYP) and TDDFT(B3LYP) spectra. Its effectiveness is illustrated using simulations of Rh L3-edge spectra tracking the C-H activation of octane by a cyclopentadienyl rhodium carbonyl complex.
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Affiliation(s)
- Luke Watson
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Thomas Pope
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Raphael M. Jay
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Ambar Banerjee
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Philippe Wernet
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Thomas J. Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
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5
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Milne CJ, Nagornova N, Pope T, Chen HY, Rossi T, Szlachetko J, Gawelda W, Britz A, van Driel TB, Sala L, Ebner S, Katayama T, Southworth SH, Doumy G, March AM, Lehmann CS, Mucke M, Iablonskyi D, Kumagai Y, Knopp G, Motomura K, Togashi T, Owada S, Yabashi M, Nielsen MM, Pajek M, Ueda K, Abela R, Penfold TJ, Chergui M. Disentangling the evolution of electrons and holes in photoexcited ZnO nanoparticles. Struct Dyn 2023; 10:064501. [PMID: 37941994 PMCID: PMC10628992 DOI: 10.1063/4.0000204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) simulations. The photoluminescence is excited at 4.66 eV, well above the band edge, and shows that electron cooling in the conduction band and exciton formation occur in <500 fs, in excellent agreement with theoretical predictions. The x-ray absorption measurements, obtained upon excitation close to the band edge at 3.49 eV, are sensitive to the migration and trapping of holes. They reveal that the 2 ps transient largely reproduces the previously reported transient obtained at 100 ps time delay in synchrotron studies. In addition, the x-ray absorption signal is found to rise in ∼1.4 ps, which we attribute to the diffusion of holes through the lattice prior to their trapping at singly charged oxygen vacancies. Indeed, the MD simulations show that impulsive trapping of holes induces an ultrafast expansion of the cage of Zn atoms in <200 fs, followed by an oscillatory response at a frequency of ∼100 cm-1, which corresponds to a phonon mode of the system involving the Zn sub-lattice.
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Affiliation(s)
| | - Natalia Nagornova
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, FSB, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Thomas Pope
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Hui-Yuan Chen
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, FSB, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Thomas Rossi
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, FSB, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | | | | | | | - Tim B. van Driel
- Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Leonardo Sala
- SwissFEL, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland
| | - Simon Ebner
- SwissFEL, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland
| | | | | | - Gilles Doumy
- Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Illinois 60439, USA
| | - Anne Marie March
- Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Illinois 60439, USA
| | | | - Melanie Mucke
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Denys Iablonskyi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Yoshiaki Kumagai
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Gregor Knopp
- SwissFEL, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland
| | - Koji Motomura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Tadashi Togashi
- Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Shigeki Owada
- RIKEN, SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148, Japan
| | - Makina Yabashi
- RIKEN, SPring-8 Center, Kouto 1-1-1, Sayo, Hyogo 679-5148, Japan
| | - Martin M. Nielsen
- Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Marek Pajek
- Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, Poznań, 61-614, Poland
| | | | - Rafael Abela
- SwissFEL, Paul Scherrer Institut, 5232 Villigen-PSI, Switzerland
| | - Thomas J. Penfold
- Chemistry—School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Majed Chergui
- Lausanne Centre for Ultrafast Science (LACUS), ISIC, FSB, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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6
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Hill NS, Cowley MV, Gluck N, Fsadni MH, Clarke W, Hu Y, Wolf MJ, Healy N, Freitag M, Penfold TJ, Richardson G, Walker AB, Cameron PJ, Docampo P. Ionic Accumulation as a Diagnostic Tool in Perovskite Solar Cells: Characterizing Band Alignment with Rapid Voltage Pulses. Adv Mater 2023; 35:e2302146. [PMID: 37145114 DOI: 10.1002/adma.202302146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/26/2023] [Indexed: 05/06/2023]
Abstract
Despite record-breaking devices, interfaces in perovskite solar cells are still poorly understood, inhibiting further progress. Their mixed ionic-electronic nature results in compositional variations at the interfaces, depending on the history of externally applied biases. This makes it difficult to measure the band energy alignment of charge extraction layers accurately. As a result, the field often resorts to a trial-and-error process to optimize these interfaces. Current approaches are typically carried out in a vacuum and on incomplete cells, hence values may not reflect those found in working devices. To address this, a pulsed measurement technique characterizing the electrostatic potential energy drop across the perovskite layer in a functioning device is developed. This method reconstructs the current-voltage (JV) curve for a range of stabilization biases, holding the ion distribution "static" during subsequent rapid voltage pulses. Two different regimes are observed: at low biases, the reconstructed JV curve is "s-shaped", whereas, at high biases, typical diode-shaped curves are returned. Using drift-diffusion simulations, it is demonstrated that the intersection of the two regimes reflects the band offsets at the interfaces. This approach effectively allows measurements of interfacial energy level alignment in a complete device under illumination and without the need for expensive vacuum equipment.
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Affiliation(s)
- Nathan S Hill
- School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU, UK
| | - Matthew V Cowley
- Centre for Sustainable and Circular Technologies, Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Nadja Gluck
- Department of Chemical Engineering, 20 Research Way (Building 82), Monash University Clayton Campus, Monash, VIC, 3800, Australia
| | - Miriam H Fsadni
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Will Clarke
- Mathematical Sciences University of Southampton, Highfield, Southampton, SO17 1BJ, UK
| | - Yinghong Hu
- Department of Chemistry and Center for NanoScience (CeNS), LMU Munich, 81377, München, Germany
| | - Matthew J Wolf
- Institute of Physical Chemistry, RWTH Aachen University, 52074, Aachen, Germany
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Noel Healy
- School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU, UK
| | - Marina Freitag
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Thomas J Penfold
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Giles Richardson
- Mathematical Sciences University of Southampton, Highfield, Southampton, SO17 1BJ, UK
| | - Alison B Walker
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Petra J Cameron
- Centre for Sustainable and Circular Technologies, Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Pablo Docampo
- School of Chemistry, University of Glasgow, University P1, Glasgow, G12 8QQ, UK
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7
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Verma S, Aznan NKN, Garside K, Penfold TJ. Uncertainty quantification of spectral predictions using deep neural networks. Chem Commun (Camb) 2023. [PMID: 37218454 DOI: 10.1039/d3cc01988h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We investigate the performance of uncertainty quantification methods, namely deep ensembles and bootstrap resampling, for deep neural network (DNN) predictions of transition metal K-edge X-ray absorption near-edge structure (XANES) spectra. Bootstrap resampling combined with our multi-layer perceptron (MLP) model provides an accurate assessment of uncertainty with >90% of all predicted spectral intensities falling within ±3σ of the true values for held-out data across the nine first-row transition metal K-edge XANES spectra.
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Affiliation(s)
- Sneha Verma
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Nik Khadijah Nik Aznan
- Research Software Engineer Group, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Kathryn Garside
- Research Software Engineer Group, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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8
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Middleton C, Rankine CD, Penfold TJ. An on-the-fly deep neural network for simulating time-resolved spectroscopy: predicting the ultrafast ring opening dynamics of 1,2-dithiane. Phys Chem Chem Phys 2023; 25:13325-13334. [PMID: 37139551 DOI: 10.1039/d3cp00510k] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Revolutionary developments in ultrafast light source technology are enabling experimental spectroscopists to probe the structural dynamics of molecules and materials on the femtosecond timescale. The capacity to investigate ultrafast processes afforded by these resources accordingly inspires theoreticians to carry out high-level simulations which facilitate the interpretation of the underlying dynamics probed during these ultrafast experiments. In this Article, we implement a deep neural network (DNN) to convert excited-state molecular dynamics simulations into time-resolved spectroscopic signals. Our DNN is trained on-the-fly from first-principles theoretical data obtained from a set of time-evolving molecular dynamics. The train-test process iterates for each time-step of the dynamics data until the network can predict spectra with sufficient accuracy to replace the computationally intensive quantum chemistry calculations required to produce them, at which point it simulates the time-resolved spectra for longer timescales. The potential of this approach is demonstrated by probing dynamics of the ring opening of 1,2-dithiane using sulphur K-edge X-ray absorption spectroscopy. The benefits of this strategy will be more markedly apparent for simulations of larger systems which will exhibit a more notable computational burden, making this approach applicable to the study of a diverse range of complex chemical dynamics.
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Affiliation(s)
- Clelia Middleton
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Conor D Rankine
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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9
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Katayama T, Choi TK, Khakhulin D, Dohn AO, Milne CJ, Vankó G, Németh Z, Lima FA, Szlachetko J, Sato T, Nozawa S, Adachi SI, Yabashi M, Penfold TJ, Gawelda W, Levi G. Atomic-scale observation of solvent reorganization influencing photoinduced structural dynamics in a copper complex photosensitizer. Chem Sci 2023; 14:2572-2584. [PMID: 36908966 PMCID: PMC9993854 DOI: 10.1039/d2sc06600a] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Photochemical reactions in solution are governed by a complex interplay between transient intramolecular electronic and nuclear structural changes and accompanying solvent rearrangements. State-of-the-art time-resolved X-ray solution scattering has emerged in the last decade as a powerful technique to observe solute and solvent motions in real time. However, disentangling solute and solvent dynamics and how they mutually influence each other remains challenging. Here, we simultaneously measure femtosecond X-ray emission and scattering to track both the intramolecular and solvation structural dynamics following photoexcitation of a solvated copper photosensitizer. Quantitative analysis assisted by molecular dynamics simulations reveals a two-step ligand flattening strongly coupled to the solvent reorganization, which conventional optical methods could not discern. First, a ballistic flattening triggers coherent motions of surrounding acetonitrile molecules. In turn, the approach of acetonitrile molecules to the copper atom mediates the decay of intramolecular coherent vibrations and induces a further ligand flattening. These direct structural insights reveal that photoinduced solute and solvent motions can be intimately intertwined, explaining how the key initial steps of light harvesting are affected by the solvent on the atomic time and length scale. Ultimately, this work takes a step forward in understanding the microscopic mechanisms of the bidirectional influence between transient solvent reorganization and photoinduced solute structural dynamics.
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Affiliation(s)
- Tetsuo Katayama
- Japan Synchrotron Radiation Research Institute Kouto 1-1-1, Sayo Hyogo 679-5198 Japan.,RIKEN SPring-8 Center 1-1-1 Kouto, Sayo Hyogo 679-5148 Japan
| | - Tae-Kyu Choi
- XFEL Division, Pohang Accelerator Laboratory Jigok-ro 127-80 Pohang 37673 Republic of Korea
| | | | - Asmus O Dohn
- Science Institute, University of Iceland 107 Reykjavík Iceland .,DTU Physics, Technical University of Denmark Kongens Lyngby Denmark
| | | | - György Vankó
- Wigner Research Centre for Physics, Hungarian Academy of Sciences H-1525 Budapest Hungary
| | - Zoltán Németh
- Wigner Research Centre for Physics, Hungarian Academy of Sciences H-1525 Budapest Hungary
| | | | - Jakub Szlachetko
- SOLARIS National Synchrotron Radiation Centre, Jagiellonian University PL-30392 Kraków Poland
| | - Tokushi Sato
- European XFEL Holzkoppel 4, Schenefeld 22869 Germany
| | - Shunsuke Nozawa
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) 1-1 Oho Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies 1-1 Oho Tsukuba Ibaraki 305-0801 Japan
| | - Shin-Ichi Adachi
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) 1-1 Oho Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies 1-1 Oho Tsukuba Ibaraki 305-0801 Japan
| | - Makina Yabashi
- RIKEN SPring-8 Center 1-1-1 Kouto, Sayo Hyogo 679-5148 Japan
| | - Thomas J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University Newcastle Upon-Tyne NE1 7RU UK
| | - Wojciech Gawelda
- Departamento de Química, Universidad Autónoma de Madrid, Campus Cantoblanco 28047 Madrid Spain.,IMDEA-Nanociencia, Campus Cantoblanco C/Faraday 9 28049 Madrid Spain.,Faculty of Physics, Adam Mickiewicz University 61-614 Poznań Poland
| | - Gianluca Levi
- Science Institute, University of Iceland 107 Reykjavík Iceland
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10
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Abstract
Excited state dynamics play a critical role across a broad range of scientific fields. Importantly, the highly non-equilibrium nature of the states generated by photoexcitation means that excited state simulations should usually include an accurate description of the coupled electronic-nuclear motion, which often requires solving the time-dependent Schrödinger equation (TDSE). One of the biggest challenges for these simulations is the requirement to calculate the PES over which the nuclei evolve. An effective approach for addressing this challenge is to use the approximate linear vibronic coupling (LVC) Hamiltonian, which enables a model potential to be parameterised using relatively few quantum chemistry calculations. However, this approach is only valid provided there are no large amplitude motions in the excited state dynamics. In this paper we introduce and deploy a metric, the global anharmonicity parameter (GAP), which can be used to assess the accuracy of an LVC potential. Following its derivation, we illustrate its utility by applying it to three molecules exhibiting different rigidity in their excited states.
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Affiliation(s)
- Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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11
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dos Santos PL, de Sa Pereira D, Eng J, Ward JS, Bryce MR, Penfold TJ, Monkman AP. Fine tuning the Photophysics of Donor‐Acceptor (D‐A3) Thermally Activated Delayed Fluorescence Emitters Using Isomerisation. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Daniel de Sa Pereira
- Durham University Physics South Road, Durham University DH1 3LE Durham UNITED KINGDOM
| | - Julien Eng
- Newcastle University School of Natural and Environmental Sciences NE1 7RU Newcastle UNITED KINGDOM
| | - Jonathan S. Ward
- University of Liverpool Chemistry Crown St L69 7ZD Liverpool UNITED KINGDOM
| | | | - Thomas J. Penfold
- Newcastle University Chemistry School of Natural and Environmental Sciences NE1 7RU Newcastle UNITED KINGDOM
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12
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Clarke RG, Weatherston J, Taj-Aldeen RA, Waddell PG, McFarlane W, Penfold TJ, Bogaerts J, Herrebout W, Mackenzie L, Pal R, Hall MJ. Synthesis and Structural Diversification of CPL Active, Helically Chiral ‘Confused’ N,N,O,C‐BODIPYs. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Rebecca Grace Clarke
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - Jake Weatherston
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - Rafid A. Taj-Aldeen
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - Paul Gordon Waddell
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - William McFarlane
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - Thomas J Penfold
- Newcastle University Chemistry, School of Natural and Environmental Sciences UNITED KINGDOM
| | - Jonathan Bogaerts
- University of Antwerp: Universiteit Antwerpen Department of Chemistry Groenenborgerlaan 171 2020 Antwerp BELGIUM
| | - Wouter Herrebout
- University of Antwerp: Universiteit Antwerpen Department of Chemistry Groenenborgerlaan 171 2020 Antwerp BELGIUM
| | - Lewis Mackenzie
- Durham University Department of Chemistry South Road DH1 3LE Durham UNITED KINGDOM
| | - Robert Pal
- Durham University Department of Chemistry Stockton Road DH1 3LE Durham UNITED KINGDOM
| | - Michael John Hall
- Newcastle University Chemistry, SNES Bedson Building NE1 7RU Newcastle upon Tyne UNITED KINGDOM
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13
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Gu Q, Chotard F, Eng J, Reponen APM, Vitorica-Yrezabal IJ, Woodward AW, Penfold TJ, Credgington D, Bochmann M, Romanov AS. Excited-State Lifetime Modulation by Twisted and Tilted Molecular Design in Carbene-Metal-Amide Photoemitters. Chem Mater 2022; 34:7526-7542. [PMID: 36032551 PMCID: PMC9404540 DOI: 10.1021/acs.chemmater.2c01938] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Carbene-metal-amides (CMAs) are an emerging class of photoemitters based on a linear donor-linker-acceptor arrangement. They exhibit high flexibility about the carbene-metal and metal-amide bonds, leading to a conformational freedom which has a strong influence on their photophysical properties. Herein we report CMA complexes with (1) nearly coplanar, (2) twisted, (3) tilted, and (4) tilt-twisted orientations between donor and acceptor ligands and illustrate the influence of preferred ground-state conformations on both the luminescence quantum yields and excited-state lifetimes. The performance is found to be optimum for structures with partially twisted and/or tilted conformations, resulting in radiative rates exceeding 1 × 106 s-1. Although the metal atoms make only small contributions to HOMOs and LUMOs, they provide sufficient spin-orbit coupling between the low-lying excited states to reduce the excited-state lifetimes down to 500 ns. At the same time, high photoluminescence quantum yields are maintained for a strongly tilted emitter in a host matrix. Proof-of-concept organic light-emitting diodes (OLEDs) based on these new emitter designs were fabricated, with a maximum external quantum efficiency (EQE) of 19.1% with low device roll-off efficiency. Transient electroluminescence studies indicate that molecular design concepts for new CMA emitters can be successfully translated into the OLED device.
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Affiliation(s)
- Qinying Gu
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | - Florian Chotard
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
| | - Julien Eng
- School
of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU, U.K.
| | - Antti-Pekka M. Reponen
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | | | - Adam W. Woodward
- Department
of Chemistry, University of Manchester, Manchester, M13 9PL, U.K.
| | - Thomas J. Penfold
- School
of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU, U.K.
| | - Dan Credgington
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | - Manfred Bochmann
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
| | - Alexander S. Romanov
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
- Department
of Chemistry, University of Manchester, Manchester, M13 9PL, U.K.
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14
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Algoazy N, Clarke RG, Penfold TJ, Waddell PG, Probert MR, Aerts R, Herrebout W, Stachelek P, Pal R, Hall MJ, Knight J. NIR Circularly Polarised Luminescence from Helically‐Extended Chiral N,N,O,O‐Boron Chelated Dipyrromethenes. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nawaf Algoazy
- Newcastle University School of natural and environmental sciences (Chemistry) School of Natural and Environmental Sciences (Chemistry)Newcastle University NE17RU Newcastle upon Tyne UNITED KINGDOM
| | - Rebecca G. Clarke
- Newcastle University School of natural and environmental sciences (Chemistry) School of Natural and Environmental Sciences (Chemistry)Newcastle University NE1 7RU Newcastle upon Tyne UNITED KINGDOM
| | - Thomas J. Penfold
- Newcastle University School of natural and environmental sciences (Chemistry) UNITED KINGDOM
| | - Paul G. Waddell
- Newcastle University School of natural and environmental sciences (Chemistry) UNITED KINGDOM
| | - Michael R. Probert
- Newcastle University School of natural and environmental sciences (Chemistry) UNITED KINGDOM
| | - Roy Aerts
- University of Antwerp: Universiteit Antwerpen department of chemistry Groenenborgerlaan 171, 2020 Antwerp BELGIUM
| | - Wouter Herrebout
- Universiteit Antwerpen Department of chemistry Groenenborgerlaan 171, 2020 Antwerp BELGIUM
| | - Patrycja Stachelek
- Durham University Department of chemistry South Road DH1 3LE Durham UNITED KINGDOM
| | - Robert Pal
- Durham University Department of chemistry UNITED KINGDOM
| | - Michael J. Hall
- Newcastle University School of natural and environmental sciences (Chemistry) School of Natural and Environmental Sciences (Chemistry)Newcastle University NE17RU Newcastle upon Tyne UNITED KINGDOM
| | - Julian Knight
- Newcastle University School of Natural and Environmental Sciences (Chemistry) School of Natural and Environmental Sciences (Chemistry)Newcastle University NE17RU Newcastle upon Tyne UNITED KINGDOM
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15
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Barlow K, Eng J, Ivalo I, Coletta M, Brechin EK, Penfold TJ, Johansson JO. Photoinduced Jahn-Teller switch in Mn(III) terpyridine complexes. Dalton Trans 2022; 51:10751-10757. [PMID: 35583816 DOI: 10.1039/d2dt00889k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultrafast transient absorption spectra were recorded for [Mn(terpy)X3], where X = Cl, F, and N3, to explore photoinduced switching from axial to equatorial Jahn-Teller (JT) distortion. Strong oscillations were observed in the transients, corresponding to a wavepacket on the excited-state potential energy surface with oscillation frequency around 115 cm-1 for all three complexes. Multireference quantum chemistry calculations indicate that the reaction coordinate is a pincer-like motion of the terpyridine ligand arising from bond length changes in the excited state due to the JT switch. We observed long dephasing times of the wavepacket, with times of 620 fs for [Mn(terpy)Cl3], 450 fs for [Mn(terpy)F3], and 370 fs for [Mn(terpy)(N3)3]. The dephasing time of these coherences decreases with an increasing number of vibrational modes at lower energy than the mode dominating the reaction coordinate, suggesting they act as an effective bath to dissipate the excess energy obtained from photoexcitation.
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Affiliation(s)
- Kyle Barlow
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
| | - Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Iona Ivalo
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
| | - Marco Coletta
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
| | - Euan K Brechin
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
| | - Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - J Olof Johansson
- EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
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16
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El-Zubir O, Martinez PR, Dura G, Al-Mahamad LLG, Pope T, Penfold TJ, Mackenzie LE, Pal R, Mosely J, Cucinotta F, McGarry LF, Horrocks BR, Houlton A. Circularly polarised luminescence in an RNA-based homochiral, self-repairing, coordination polymer hydrogel. J Mater Chem C Mater 2022; 10:7329-7335. [PMID: 35706420 PMCID: PMC9097859 DOI: 10.1039/d2tc00366j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
The aqueous equimolar reaction of Ag(i) ions with the thionucleoside enantiomer (-)6-thioguanosine, ((-)6tGH), yields a one-dimensional coordination polymer {Ag(-)tG} n , the self-assembly of which generates left-handed helical chains. The resulting helicity induces an enhanced chiro-optical response compared to the parent ligand. DFT calculations indicate that this enhancement is due to delocalisation of the excited state along the helical chains, with 7 units being required to converge the calculated CD spectra. At concentrations ≥15 mmol l-1 reactions form a sample-spanning hydrogel which shows self-repair capabilities with instantaneous recovery in which the dynamic reversibility of the coordination chains appears to play a role. The resulting gel exhibits circularly polarised luminescence (CPL) with a large dissymmetry factor of -0.07 ± 0.01 at 735 nm, a phenomenon not previously observed for this class of coordination polymer.
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Affiliation(s)
- Osama El-Zubir
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Pablo Rojas Martinez
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Gema Dura
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Ciencias y Tecnologías Químicas, UCLM Spain
| | - Lamia L G Al-Mahamad
- Department of Chemistry, College of Science, Mustansiriyah University Baghdad Iraq
| | - Thomas Pope
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Thomas J Penfold
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Lewis E Mackenzie
- Department of Chemistry, Durham University South Road Durham DH1 3LE UK
| | - Robert Pal
- Department of Chemistry, Durham University South Road Durham DH1 3LE UK
| | - Jackie Mosely
- Department of Chemistry, Durham University South Road Durham DH1 3LE UK
| | - Fabio Cucinotta
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Liam F McGarry
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Benjamin R Horrocks
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Andrew Houlton
- Chemical Nanoscience Labs, Chemistry, School of Natural Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
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17
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Rankine CD, Penfold TJ. Accurate, affordable, and generalizable machine learning simulations of transition metal x-ray absorption spectra using the XANESNET deep neural network. J Chem Phys 2022; 156:164102. [PMID: 35490005 DOI: 10.1063/5.0087255] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The affordable, accurate, and generalizable prediction of spectroscopic observables plays a key role in the analysis of increasingly complex experiments. In this article, we develop and deploy a deep neural network-XANESNET-for predicting the lineshape of first-row transition metal K-edge x-ray absorption near-edge structure (XANES) spectra. XANESNET predicts the spectral intensities using only information about the local coordination geometry of the transition metal complexes encoded in a feature vector of weighted atom-centered symmetry functions. We address in detail the calibration of the feature vector for the particularities of the problem at hand, and we explore the individual feature importance to reveal the physical insight that XANESNET obtains at the Fe K-edge. XANESNET relies on only a few judiciously selected features-radial information on the first and second coordination shells suffices along with angular information sufficient to separate satisfactorily key coordination geometries. The feature importance is found to reflect the XANES spectral window under consideration and is consistent with the expected underlying physics. We subsequently apply XANESNET at nine first-row transition metal (Ti-Zn) K-edges. It can be optimized in as little as a minute, predicts instantaneously, and provides K-edge XANES spectra with an average accuracy of ∼±2%-4% in which the positions of prominent peaks are matched with a >90% hit rate to sub-eV (∼0.8 eV) error.
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Affiliation(s)
- C D Rankine
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
| | - T J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne NE1 7RU, United Kingdom
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18
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Watson L, Rankine CD, Penfold TJ. Beyond structural insight: a deep neural network for the prediction of Pt L 2/3-edge X-ray absorption spectra. Phys Chem Chem Phys 2022; 24:9156-9167. [PMID: 35393987 DOI: 10.1039/d2cp00567k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
X-ray absorption spectroscopy at the L2/3 edge can be used to obtain detailed information about the local electronic and geometric structure of transition metal complexes. By virtue of the dipole selection rules, the transition metal L2/3 edge usually exhibits two distinct spectral regions: (i) the "white line", which is dominated by bound electronic transitions from metal-centred 2p orbitals into unoccupied orbitals with d character; the intensity and shape of this band consequently reflects the d density of states (d-DOS), which is strongly modulated by mixing with ligand orbitals involved in chemical bonding, and (ii) the post-edge, where oscillations encode the local geometric structure around the X-ray absorption site. In this Article, we extend our recently-developed XANESNET deep neural network (DNN) beyond the K-edge to predict X-ray absorption spectra at the Pt L2/3 edge. We demonstrate that XANESNET is able to predict Pt L2/3 -edge X-ray absorption spectra, including both the parts containing electronic and geometric structural information. The performance of our DNN in practical situations is demonstrated by application to two Pt complexes, and by simulating the transient spectrum of a photoexcited dimeric Pt complex. Our discussion includes an analysis of the feature importance in our DNN which demonstrates the role of key features and assists with interpreting the performance of the network.
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Affiliation(s)
- Luke Watson
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle, upon Tyne, NE1 7RU, UK.
| | - Conor D Rankine
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle, upon Tyne, NE1 7RU, UK.
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle, upon Tyne, NE1 7RU, UK.
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19
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Davison N, Waddell PG, Dixon C, Wills C, Penfold TJ, Lu E. A monomeric (trimethylsilyl)methyl lithium complex: synthesis, structure, decomposition and preliminary reactivity studies. Dalton Trans 2021; 51:10707-10713. [PMID: 34854445 DOI: 10.1039/d1dt03532k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monomeric organolithium (LiR) complexes could provide enhanced Li-C bond reactivity and suggest mechanisms for a plethora of LiR-mediated reactions. They are highly sought-after but remain a synthetic challenge for organometallic chemists. In this work, we report the synthesis and characterisation of a monomeric (trimethylsilyl)methyl lithium complex, namely [Li(CH2SiMe3)(κ3-N,N',N''-Me6Tren)] (1), where Me6Tren is a tetradentate neutral amine ligand. The structure of 1 was comprehensively examined by single-crystal X-ray diffraction, variable temperature NMR spectroscopy and electron absorption spectroscopy. Complex 1 decomposes via ligand C-H and C-N activations to produce a Li amide complex 2. Preliminary reactivity studies of 1 reveal CO insertion and C-H activation reaction patterns.
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Affiliation(s)
- Nathan Davison
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Paul G Waddell
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Casey Dixon
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Corinne Wills
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Thomas J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Erli Lu
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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20
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Laidlaw B, Eng J, Wade J, Shi X, Salerno F, Fuchter MJ, Penfold TJ. On the factors influencing the chiroptical response of conjugated polymer thin films. Chem Commun (Camb) 2021; 57:9914-9917. [PMID: 34498020 DOI: 10.1039/d1cc02918e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the influence of the physical and chemical structure on the chiroptical response of fluorene-based polymeric systems, namely poly(9,9-dioctylfluorene) (PFO) and the donor-acceptor type copolymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). We reveal the significance of electric-magnetic coupling, at both short (molecular-level) and intermediate (delocalised over multiple polymer chains) length scales, on the magnitude of the dissymmetry. These findings provide a framework for the design of new materials with an enhanced chiroptical response.
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Affiliation(s)
- Beth Laidlaw
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Julien Eng
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Jessica Wade
- Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Xingyuan Shi
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Francesco Salerno
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Matthew J Fuchter
- Centre for Processable Electronics, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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21
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Hainer F, Alagna N, Reddy Marri A, Penfold TJ, Gros PC, Haacke S, Buckup T. Vibrational Coherence Spectroscopy Identifies Ultrafast Branching in an Iron(II) Sensitizer. J Phys Chem Lett 2021; 12:8560-8565. [PMID: 34468159 DOI: 10.1021/acs.jpclett.1c01580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The introduction of N-heterocyclic carbene ligands has greatly increased the lifetimes of metal-to-ligand charge transfer states (MLCT) in iron(II) complexes, making them promising candidates for photocatalytic applications. However, the spectrally elusive triplet metal-centered state (3MC) has been suggested to play a decisive role in the relaxation of the MLCT manifold to the ground state, shortening their lifetimes and consequently limiting the application potential. In this work, time-resolved vibrational spectroscopy and quantum chemical calculations are applied to shed light on the 3MCs' involvement in the deactivation of the MLCT manifold of an iron(II) sensitizer. Two distinct symmetric Fe-L breathing vibrations at frequencies below 150 cm-1 are assigned to the 3MC and 3MLCT states by quantum chemical calculations. On the basis of this assignment, an ultrafast branching directly after excitation forms not only the long-lived 3MLCT but also the 3MC as an additional loss channel.
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Affiliation(s)
- F Hainer
- Physikalisch Chemisches Institut, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
| | - N Alagna
- Physikalisch Chemisches Institut, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
| | - A Reddy Marri
- Université de Lorraine, CNRS, L2CM, F-54000 Nancy, France
| | - T J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, NE1 7RU Newcastle Upon Tyne, United Kingdom
| | - P C Gros
- Université de Lorraine, CNRS, L2CM, F-54000 Nancy, France
| | - S Haacke
- University of Strasbourg, CNRS, IPCMS, 67034 Strasbourg, France
| | - T Buckup
- Physikalisch Chemisches Institut, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls Universität, D-69120 Heidelberg, Germany
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22
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Yang L, Horton JT, Payne MC, Penfold TJ, Cole DJ. Modeling Molecular Emitters in Organic Light-Emitting Diodes with the Quantum Mechanical Bespoke Force Field. J Chem Theory Comput 2021; 17:5021-5033. [PMID: 34264669 DOI: 10.1021/acs.jctc.1c00135] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Combined molecular dynamics (MD) and quantum mechanics (QM) simulation procedures have gained popularity in modeling the spectral properties of functional organic molecules. However, the potential energy surfaces used to propagate long-time scale dynamics in these simulations are typically described using general, transferable force fields designed for organic molecules in their electronic ground states. These force fields do not typically include spectroscopic data in their training, and importantly, there is no general protocol for including changes in geometry or intermolecular interactions with the environment that may occur upon electronic excitation. In this work, we show that parameters tailored for thermally activated delayed fluorescence (TADF) emitters used in organic light-emitting diodes (OLEDs), in both their ground and electronically excited states, can be readily derived from a small number of QM calculations using the QUBEKit (QUantum mechanical BEspoke toolKit) software and improve the overall accuracy of these simulations.
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Affiliation(s)
- Lupeng Yang
- TCM Group, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Joshua T Horton
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Michael C Payne
- TCM Group, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Thomas J Penfold
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Daniel J Cole
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
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23
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Greenfield JL, Wade J, Brandt JR, Shi X, Penfold TJ, Fuchter MJ. Pathways to increase the dissymmetry in the interaction of chiral light and chiral molecules. Chem Sci 2021; 12:8589-8602. [PMID: 34257860 PMCID: PMC8246297 DOI: 10.1039/d1sc02335g] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 05/20/2021] [Indexed: 11/23/2022] Open
Abstract
The dissymmetric interaction between circularly polarised (CP) light and chiral molecules is central to a range of areas, from spectroscopy and imaging to next-generation photonic devices. However, the selectivity in absorption or emission of left-handed versus right-handed CP light is low for many molecular systems. In this perspective, we assess the magnitude of the measured chiroptical response for a variety of chiral systems, ranging from small molecules to large supramolecular assemblies, and highlight the challenges towards enhancing chiroptical activity. We explain the origins of low CP dissymmetry and showcase recent examples in which molecular design, and the modification of light itself, enable larger responses. Our discussion spans spatial extension of the chiral chromophore, manipulation of transition dipole moments, exploitation of forbidden transitions and creation of macroscopic chiral structures; all of which can increase the dissymmetry. Whilst the specific strategy taken to enhance the dissymmetric interaction will depend on the application of interest, these approaches offer hope for the development and advancement of all research fields that involve interactions of chiral molecules and light.
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Affiliation(s)
- Jake L Greenfield
- Department of Chemistry and Molecular Sciences Research Hub, Imperial College London, White City Campus 82 Wood Lane London W12 0BZ UK
| | - Jessica Wade
- Department of Materials, Imperial College London Exhibition Road SW7 2AZ UK
- Centre for Processable Electronics, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Jochen R Brandt
- Department of Chemistry and Molecular Sciences Research Hub, Imperial College London, White City Campus 82 Wood Lane London W12 0BZ UK
- Centre for Processable Electronics, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Xingyuan Shi
- Department of Chemistry and Molecular Sciences Research Hub, Imperial College London, White City Campus 82 Wood Lane London W12 0BZ UK
- Centre for Processable Electronics, Imperial College London, South Kensington Campus London SW7 2AZ UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Matthew J Fuchter
- Department of Chemistry and Molecular Sciences Research Hub, Imperial College London, White City Campus 82 Wood Lane London W12 0BZ UK
- Centre for Processable Electronics, Imperial College London, South Kensington Campus London SW7 2AZ UK
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24
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Abstract
Methyllithium (MeLi) is the parent archetypal organolithium complex. MeLi exists as aggregates in solutions and solid states. Monomeric MeLi is postulated as a highly reactive intermediate and plays a vital role in understanding MeLi-mediated reactions but has not been isolated. Herein, we report the synthesis and structure of the first monomeric MeLi complex enabled by a new hexadentate neutral amine ligand.
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Affiliation(s)
- Nathan Davison
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Emanuele Falbo
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Paul G Waddell
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Thomas J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
| | - Erli Lu
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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25
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Affiliation(s)
- Julien Eng
- grid.1006.70000 0001 0462 7212Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Thomas J. Penfold
- grid.1006.70000 0001 0462 7212Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, UK
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26
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Rajamalli P, Rizzi F, Li W, Jinks MA, Gupta AK, Laidlaw BA, Samuel IDW, Penfold TJ, Goldup SM, Zysman‐Colman E. Using the Mechanical Bond to Tune the Performance of a Thermally Activated Delayed Fluorescence Emitter*. Angew Chem Int Ed Engl 2021; 60:12066-12073. [PMID: 33666324 PMCID: PMC8251797 DOI: 10.1002/anie.202101870] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Indexed: 12/12/2022]
Abstract
We report the characterization of rotaxanes based on a carbazole-benzophenone thermally activated delayed fluorescence luminophore. We find that the mechanical bond leads to an improvement in key photophysical properties of the emitter, notably an increase in photoluminescence quantum yield and a decrease in the energy difference between singlet and triplet states, as well as fine tuning of the emission wavelength, a feat that is difficult to achieve when using covalently bound substituents. Computational simulations, supported by X-ray crystallography, suggest that this tuning of properties occurs due to weak interactions between the axle and the macrocycle that are enforced by the mechanical bond. This work highlights the benefits of using the mechanical bond to refine existing luminophores, providing a new avenue for emitter optimization that can ultimately increase the performance of these molecules.
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Affiliation(s)
- Pachaiyappan Rajamalli
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
- Materials Research CentreIndian Institute of ScienceBangalore560012India
| | - Federica Rizzi
- ChemistryUniversity of SouthamptonHighfieldSouthamptonSO17 1BJUK
| | - Wenbo Li
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsSt AndrewsFifeKY16 9SSUK
| | - Michael A. Jinks
- ChemistryUniversity of SouthamptonHighfieldSouthamptonSO17 1BJUK
| | - Abhishek Kumar Gupta
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsSt AndrewsFifeKY16 9SSUK
| | - Beth A. Laidlaw
- Chemistry, School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
| | - Ifor D. W. Samuel
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsSt AndrewsFifeKY16 9SSUK
| | - Thomas J. Penfold
- Chemistry, School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
| | | | - Eli Zysman‐Colman
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsSt AndrewsFifeKY16 9STUK
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27
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Rajamalli P, Rizzi F, Li W, Jinks MA, Gupta AK, Laidlaw BA, Samuel IDW, Penfold TJ, Goldup SM, Zysman‐Colman E. Using the Mechanical Bond to Tune the Performance of a Thermally Activated Delayed Fluorescence Emitter**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pachaiyappan Rajamalli
- Organic Semiconductor Centre EaStCHEM School of Chemistry University of St Andrews St Andrews Fife KY16 9ST UK
- Materials Research Centre Indian Institute of Science Bangalore 560012 India
| | - Federica Rizzi
- Chemistry University of Southampton Highfield Southampton SO17 1BJ UK
| | - Wenbo Li
- Organic Semiconductor Centre SUPA School of Physics and Astronomy University of St Andrews St Andrews Fife KY16 9SS UK
| | - Michael A. Jinks
- Chemistry University of Southampton Highfield Southampton SO17 1BJ UK
| | - Abhishek Kumar Gupta
- Organic Semiconductor Centre EaStCHEM School of Chemistry University of St Andrews St Andrews Fife KY16 9ST UK
- Organic Semiconductor Centre SUPA School of Physics and Astronomy University of St Andrews St Andrews Fife KY16 9SS UK
| | - Beth A. Laidlaw
- Chemistry, School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre SUPA School of Physics and Astronomy University of St Andrews St Andrews Fife KY16 9SS UK
| | - Thomas J. Penfold
- Chemistry, School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Stephen M. Goldup
- Chemistry University of Southampton Highfield Southampton SO17 1BJ UK
| | - Eli Zysman‐Colman
- Organic Semiconductor Centre EaStCHEM School of Chemistry University of St Andrews St Andrews Fife KY16 9ST UK
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28
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Shaikh J, Congrave DG, Forster A, Minotto A, Cacialli F, Hele TJH, Penfold TJ, Bronstein H, Clarke TM. Intrinsic photogeneration of long-lived charges in a donor-orthogonal acceptor conjugated polymer. Chem Sci 2021; 12:8165-8177. [PMID: 34194707 PMCID: PMC8208312 DOI: 10.1039/d1sc00919b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/08/2021] [Indexed: 11/21/2022] Open
Abstract
Efficient charge photogeneration in conjugated polymers typically requires the presence of a second component to act as electron acceptor. Here, we report a novel low band-gap conjugated polymer with a donor/orthogonal acceptor motif: poly-2,6-(4,4-dihexadecyl-4H-cyclopenta [2,1-b:3,4-b']dithiophene)-alt-2,6-spiro [cyclopenta[2,1-b:3,4-b']dithiophene-4,9'-fluorene]-2',7'-dicarbonitrile, referred to as PCPDT-sFCN. The role of the orthogonal acceptor is to spatially isolate the LUMO from the HOMO, allowing for negligible exchange energy between electrons in these orbitals and minimising the energy gap between singlet and triplet charge transfer states. We employ ultrafast and microsecond transient absorption spectroscopy to demonstrate that, even in the absence of a separate electron acceptor, PCPDT-sFCN shows efficient charge photogeneration in both pristine solution and film. This efficient charge generation is a result of an isoenergetic singlet/triplet charge transfer state equilibrium acting as a reservoir for charge carrier formation. Furthermore, clear evidence of enhanced triplet populations, which form in less than 1 ps, is observed. Using group theory, we show that this ultrafast triplet formation is due to highly efficient, quantum mechanically allowed intersystem crossing between the bright, initially photoexcited local singlet state and the triplet charge transfer state. Remarkably, the free charges that form via the charge transfer state are extraordinarily long-lived with millisecond lifetimes, possibly due to the stabilisation imparted by the spatial separation of PCPDT-sFCN's donor and orthogonal acceptor motifs. The efficient generation of long-lived charge carriers in a pristine polymer paves the way for single-material applications such as organic photovoltaics and photodetectors.
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Affiliation(s)
- Jordan Shaikh
- Department of Chemistry, University College London Christopher Ingold Building London WC1H 0AJ UK
| | - Daniel G Congrave
- Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Alex Forster
- Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Alessandro Minotto
- Department of Physics, University College London Gower Street London WC1E 6BT UK
| | - Franco Cacialli
- Department of Physics, University College London Gower Street London WC1E 6BT UK
| | - Timothy J H Hele
- Department of Chemistry, University College London Christopher Ingold Building London WC1H 0AJ UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | - Hugo Bronstein
- Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Tracey M Clarke
- Department of Chemistry, University College London Christopher Ingold Building London WC1H 0AJ UK
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29
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Madkhali MMM, Rankine CD, Penfold TJ. Enhancing the analysis of disorder in X-ray absorption spectra: application of deep neural networks to T-jump-X-ray probe experiments. Phys Chem Chem Phys 2021; 23:9259-9269. [PMID: 33885072 DOI: 10.1039/d0cp06244h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many chemical and biological reactions, including ligand exchange processes, require thermal energy for the reactants to overcome a transition barrier and reach the product state. Temperature-jump (T-jump) spectroscopy uses a near-infrared (NIR) pulse to rapidly heat a sample, offering an approach for triggering these processes and directly accessing thermally-activated pathways. However, thermal activation inherently increases the disorder of the system under study and, as a consequence, can make quantitative interpretations of structural changes challenging. In this Article, we optimise a deep neural network (DNN) for the instantaneous prediction of Co K-edge X-ray absorption near-edge structure (XANES) spectra. We apply our DNN to analyse T-jump pump/X-ray probe data pertaining to the ligand exchange processes and solvation dynamics of Co2+ in chlorinated aqueous solution. Our analysis is greatly facilitated by machine learning, as our DNN is able to predict quickly and cost-effectively the XANES spectra of thousands of geometric configurations sampled from ab initio molecular dynamics (MD) using nothing more than the local geometric environment around the X-ray absorption site. We identify directly the structural changes following the T-jump, which are dominated by sample heating and a commensurate increase in the Debye-Waller factor.
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Affiliation(s)
- Marwah M M Madkhali
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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30
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Pander P, Daniels R, Zaytsev AV, Horn A, Sil A, Penfold TJ, Williams JAG, Kozhevnikov VN, Dias FB. Exceptionally fast radiative decay of a dinuclear platinum complex through thermally activated delayed fluorescence. Chem Sci 2021; 12:6172-6180. [PMID: 33996015 PMCID: PMC8098751 DOI: 10.1039/d1sc00160d] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/19/2021] [Indexed: 12/13/2022] Open
Abstract
A novel dinuclear platinum(ii) complex featuring a ditopic, bis-tetradentate ligand has been prepared. The ligand offers each metal ion a planar O^N^C^N coordination environment, with the two metal ions bound to the nitrogen atoms of a bridging pyrimidine unit. The complex is brightly luminescent in the red region of the spectrum with a photoluminescence quantum yield of 83% in deoxygenated methylcyclohexane solution at ambient temperature, and shows a remarkably short excited state lifetime of 2.1 μs. These properties are the result of an unusually high radiative rate constant of around 4 × 105 s-1, a value which is comparable to that of the very best performing Ir(iii) complexes. This unusual behaviour is the result of efficient thermally activated reverse intersystem crossing, promoted by a small singlet-triplet energy difference of only 69 ± 3 meV. The complex was incorporated into solution-processed OLEDs achieving EQEmax = 7.4%. We believe this to be the first fully evidenced report of a Pt(ii) complex showing thermally activated delayed fluorescence (TADF) at room temperature, and indeed of a Pt(ii)-based delayed fluorescence emitter to be incorporated into an OLED.
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Affiliation(s)
- Piotr Pander
- Department of Physics, Durham University South Road Durham DH1 3LE UK
| | - Ruth Daniels
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Andrey V Zaytsev
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Ashleigh Horn
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Amit Sil
- Department of Chemistry, Durham University South Road Durham DH1 3LE UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | | | - Valery N Kozhevnikov
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Fernando B Dias
- Department of Physics, Durham University South Road Durham DH1 3LE UK
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31
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Eng J, Penfold TJ. Understanding and Designing Thermally Activated Delayed Fluorescence Emitters: Beyond the Energy Gap Approximation. CHEM REC 2020; 20:831-856. [PMID: 32267093 DOI: 10.1002/tcr.202000013] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/13/2020] [Indexed: 11/08/2022]
Abstract
In this article recent progress in the development of molecules exhibiting Thermally Activated Delayed Fluorescence (TADF) is discussed with a particular focus upon their application as emitters in highly efficient organic light emitting diodes (OLEDs). The key aspects controlling the desirable functional properties, e. g. fast intersystem crossing, high radiative rate and unity quantum yield, are introduced with a particular focus upon the competition between the key requirements needed to achieve high performance OLEDs. The design rules required for organic and metal organic materials are discussed, and the correlation between them outlined. Recent progress towards understanding the influence of the interaction between a molecule and its environment are explained as is the role of the mechanism for excited state formation in OLEDs. Finally, all of these aspects are combined to discuss the ability to implement high level design rules for achieving higher quality materials for commercial applications. This article highlights the significant progress that has been made in recent years, but also outlines the significant challenges which persist to achieve a full understanding of the TADF mechanism and improve the stability and performance of these materials.
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Affiliation(s)
- Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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32
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Liedy F, Eng J, McNab R, Inglis R, Penfold TJ, Brechin EK, Johansson JO. Vibrational coherences in manganese single-molecule magnets after ultrafast photoexcitation. Nat Chem 2020; 12:452-458. [PMID: 32123341 DOI: 10.1038/s41557-020-0431-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/27/2020] [Indexed: 11/09/2022]
Abstract
Magnetic recording using femtosecond laser pulses has recently been achieved in some dielectric media, showing potential for ultrafast data storage applications. Single-molecule magnets (SMMs) are metal complexes with two degenerate magnetic ground states and are promising for increasing storage density, but remain unexplored using ultrafast techniques. Here we have explored the dynamics occurring after photoexcitation of a trinuclear µ3-oxo-bridged Mn(III)-based SMM, whose magnetic anisotropy is closely related to the Jahn-Teller distortion. Ultrafast transient absorption spectroscopy in solution reveals oscillations superimposed on the decay traces due to a vibrational wavepacket. Based on complementary measurements and calculations on the monomer Mn(acac)3, we conclude that the wavepacket motion in the trinuclear SMM is constrained along the Jahn-Teller axis due to the µ3-oxo and µ-oxime bridges. Our results provide new possibilities for optical control of the magnetization in SMMs on femtosecond timescales and open up new molecular-design challenges to control the wavepacket motion in the excited state of polynuclear transition-metal complexes.
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Affiliation(s)
- Florian Liedy
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Julien Eng
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Robbie McNab
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Ross Inglis
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Thomas J Penfold
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Euan K Brechin
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - J Olof Johansson
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK.
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33
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Pápai M, Rozgonyi T, Penfold TJ, Nielsen MM, Møller KB. Simulation of ultrafast excited-state dynamics and elastic x-ray scattering by quantum wavepacket dynamics. J Chem Phys 2019; 151:104307. [DOI: 10.1063/1.5115204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Mátyás Pápai
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
| | - Tamás Rozgonyi
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O. Box 286, H-1519 Budapest, Hungary
| | - Thomas J. Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Martin M. Nielsen
- Department of Physics, Technical University of Denmark, Fysikvej 307, DK-2800 Kongens Lyngby, Denmark
| | - Klaus B. Møller
- Department of Chemistry, Technical University of Denmark, Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark
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34
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Katayama T, Northey T, Gawelda W, Milne CJ, Vankó G, Lima FA, Bohinc R, Németh Z, Nozawa S, Sato T, Khakhulin D, Szlachetko J, Togashi T, Owada S, Adachi SI, Bressler C, Yabashi M, Penfold TJ. Tracking multiple components of a nuclear wavepacket in photoexcited Cu(I)-phenanthroline complex using ultrafast X-ray spectroscopy. Nat Commun 2019; 10:3606. [PMID: 31399565 PMCID: PMC6689108 DOI: 10.1038/s41467-019-11499-w] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/18/2019] [Indexed: 11/09/2022] Open
Abstract
Disentangling the strong interplay between electronic and nuclear degrees of freedom is essential to achieve a full understanding of excited state processes during ultrafast nonadiabatic chemical reactions. However, the complexity of multi-dimensional potential energy surfaces means that this remains challenging. The energy flow during vibrational and electronic relaxation processes can be explored with structural sensitivity by probing a nuclear wavepacket using femtosecond time-resolved X-ray Absorption Near Edge Structure (TR-XANES). However, it remains unknown to what level of detail vibrational motions are observable in this X-ray technique. Herein we track the wavepacket dynamics of a prototypical [Cu(2,9-dimethyl-1,10-phenanthroline)2]+ complex using TR-XANES. We demonstrate that sensitivity to individual wavepacket components can be modulated by the probe energy and that the bond length change associated with molecular breathing mode can be tracked with a sub-Angstrom resolution beyond optical-domain observables. Importantly, our results reveal how state-of-the-art TR-XANES provides deeper insights of ultrafast nonadiabatic chemical reactions.
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Affiliation(s)
- Tetsuo Katayama
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo, 679-5198, Japan. .,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan.
| | - Thomas Northey
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne, NE1 7RU, UK
| | - Wojciech Gawelda
- European XFEL, Holzkoppel 4, 22869, Schenefeld, Germany.,Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland
| | | | - György Vankó
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, 1525, Budapest, Hungary
| | | | - Rok Bohinc
- SwissFEL, Paul Scherrer Institut, 5232, Villigen-PSI, Switzerland
| | - Zoltán Németh
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, 1525, Budapest, Hungary
| | - Shunsuke Nozawa
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan
| | - Tokushi Sato
- European XFEL, Holzkoppel 4, 22869, Schenefeld, Germany.,Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607, Hamburg, Germany
| | | | - Jakub Szlachetko
- Institute of Nuclear Physics, Polish Academy of Sciences, 31-342, Kraków, Poland
| | - Tadashi Togashi
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo, 679-5198, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Shigeki Owada
- Japan Synchrotron Radiation Research Institute, Kouto 1-1-1, Sayo, Hyogo, 679-5198, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Shin-Ichi Adachi
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan
| | - Christian Bressler
- European XFEL, Holzkoppel 4, 22869, Schenefeld, Germany.,Centre for Ultrafast Imaging CUI, University of Hamburg, 22761, Hamburg, Germany
| | - Makina Yabashi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Thomas J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne, NE1 7RU, UK.
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35
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Eng J, Laidlaw BA, Penfold TJ. On the geometry dependence of tuned‐range separated hybrid functionals. J Comput Chem 2019; 40:2191-2199. [DOI: 10.1002/jcc.25868] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/03/2019] [Accepted: 05/07/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Julien Eng
- Chemistry School of Natural and Environmental SciencesNewcastle University Newcastle upon Tyne NE1 7RU United Kingdom
| | - Beth A. Laidlaw
- Chemistry School of Natural and Environmental SciencesNewcastle University Newcastle upon Tyne NE1 7RU United Kingdom
| | - Thomas J. Penfold
- Chemistry School of Natural and Environmental SciencesNewcastle University Newcastle upon Tyne NE1 7RU United Kingdom
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36
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Abstract
Excited state energy transfer in disordered systems has attracted significant attention owing to the importance of this phenomenon in both artificial and natural systems that operate in electronically excited states. Of particular interest, especially in the context of organic electronics, is the dynamics of triplet excited states. Due to their weak coupling to the singlet manifold they can often act as low energy trapping sites and are therefore detrimental to device performance. Alternatively, by virtue of their long lifetime they can lead to enhanced diffusion lengths important for organic photovoltaics (OPV). Herein, we explore the triplet energy transfer mechanism from dichlorobenzene to thioxanthone in methanol solution. We rationalise previous experimental observations as arising from preferential population transfer into the lowest triplet state rather than the higher lying triplet state that is closer in energy. The reason for this is a delicate balance between the electronic coupling, reorganisation energy and the energy gap involved. The present results provide the understanding to potentially develop a hot exciton mechanism in materials for organic light emitting diodes (OLED) to achieve higher device efficiencies.
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Affiliation(s)
- T Northey
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
| | - T Keane
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
| | - J Eng
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
| | - T J Penfold
- Chemistry-School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
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Pápai M, Simmermacher M, Penfold TJ, Møller KB, Rozgonyi T. How To Excite Nuclear Wavepackets into Electronically Degenerate States in Spin-Vibronic Quantum Dynamics Simulations. J Chem Theory Comput 2018; 14:3967-3974. [DOI: 10.1021/acs.jctc.8b00135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Mátyás Pápai
- Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
| | - Mats Simmermacher
- Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Thomas J. Penfold
- Chemistry—School of Natural and Environmental Science, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Klaus B. Møller
- Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Tamás Rozgonyi
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O. Box 286, H-1519 Budapest, Hungary
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38
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dos Santos PL, Ward JS, Congrave DG, Batsanov AS, Eng J, Stacey JE, Penfold TJ, Monkman AP, Bryce MR. Triazatruxene: A Rigid Central Donor Unit for a D-A 3 Thermally Activated Delayed Fluorescence Material Exhibiting Sub-Microsecond Reverse Intersystem Crossing and Unity Quantum Yield via Multiple Singlet-Triplet State Pairs. Adv Sci (Weinh) 2018; 5:1700989. [PMID: 29938177 PMCID: PMC6010696 DOI: 10.1002/advs.201700989] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/08/2018] [Indexed: 05/23/2023]
Abstract
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 utilization of triplet excited states at faster rates than Ir-based phosphorescent materials. A combination of the inverted structure and multiple donor-acceptor interactions yields up to 30 vibronically coupled singlet and triplet states within 0.2 eV that are involved in rISC. This gives a significant enhancement to the rISC rate, leading to delayed fluorescence decay times as low as 103.9 ns. This new material also has an emission quantum yield ≈1 and a very small singlet-triplet gap. This work shows that it is possible to achieve both high photoluminescence quantum yield and fast rISC in the same molecule. Green organic light-emitting diode devices with external quantum efficiency >30% are demonstrated at 76 cd m-2.
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Affiliation(s)
| | - Jonathan S. Ward
- Department of ChemistryDurham UniversitySouth RoadDurhamDH1 3LEUK
| | | | | | - Julien Eng
- Chemistry School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
| | - Jessica E. Stacey
- Chemistry School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
| | - Thomas J. Penfold
- Chemistry School of Natural and Environmental SciencesNewcastle UniversityNewcastle upon TyneNE1 7RUUK
| | | | - Martin R. Bryce
- Department of ChemistryDurham UniversitySouth RoadDurhamDH1 3LEUK
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39
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Affiliation(s)
- Thomas J. Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne NE1 7RU, United Kingdom
| | - Etienne Gindensperger
- Laboratoire de Chimie Quantique, Institut de Chimie UMR-7177, CNRS - Université de Strasbourg, 1 Rue Blaise Pascal 67008 Strasbourg, France
| | - Chantal Daniel
- Laboratoire de Chimie Quantique, Institut de Chimie UMR-7177, CNRS - Université de Strasbourg, 1 Rue Blaise Pascal 67008 Strasbourg, France
| | - Christel M. Marian
- Institut für Theoretische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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40
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Pander P, Bulmer R, Martinscroft R, Thompson S, Lewis FW, Penfold TJ, Dias FB, Kozhevnikov VN. 1,2,4-Triazines in the Synthesis of Bipyridine Bisphenolate ONNO Ligands and Their Highly Luminescent Tetradentate Pt(II) Complexes for Solution-Processable OLEDs. Inorg Chem 2018. [DOI: 10.1021/acs.inorgchem.7b03175] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Piotr Pander
- Department of Physics, Durham University, Durham, South Road, DH1 3LE U.K
| | - Rachel Bulmer
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, Tyne and Wear, NE1 8ST U.K
| | - Ross Martinscroft
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, Tyne and Wear, NE1 8ST U.K
| | - Stuart Thompson
- School of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU U.K
| | - Frank W. Lewis
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, Tyne and Wear, NE1 8ST U.K
| | - Thomas J. Penfold
- School of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU U.K
| | - Fernando B. Dias
- Department of Physics, Durham University, Durham, South Road, DH1 3LE U.K
| | - Valery N. Kozhevnikov
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, Tyne and Wear, NE1 8ST U.K
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41
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Cooper GA, Medcraft C, Littlefair JD, Penfold TJ, Walker NR. Halogen bonding properties of 4-iodopyrazole and 4-bromopyrazole explored by rotational spectroscopy and ab initio calculations. J Chem Phys 2017; 147:214303. [DOI: 10.1063/1.5002662] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Graham. A. Cooper
- Chemistry–School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom
| | - Chris Medcraft
- Chemistry–School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom
| | - Josh D. Littlefair
- Chemistry–School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom
| | - Thomas J. Penfold
- Chemistry–School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom
| | - Nicholas R. Walker
- Chemistry–School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle-upon-Tyne NE1 7RU, United Kingdom
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42
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Clarke R, Ho KL, Alsimaree AA, Woodford OJ, Waddell PG, Bogaerts J, Herrebout W, Knight JG, Pal R, Penfold TJ, Hall MJ. Circularly Polarised Luminescence from Helically Chiral “Confused” N
,N
,O
,C
-Boron-Chelated Dipyrromethenes (BODIPYs). CHEMPHOTOCHEM 2017. [DOI: 10.1002/cptc.201700106] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Rebecca Clarke
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | - Kin Lok Ho
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | | | - Owen J. Woodford
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | - Paul G. Waddell
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | - Jonathan Bogaerts
- Department of Chemistry; University of Antwerp; Groenenborgerlaan 171 2020 Antwerp Belgium
| | - Wouter Herrebout
- Department of Chemistry; University of Antwerp; Groenenborgerlaan 171 2020 Antwerp Belgium
| | - Julian G. Knight
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | - Robert Pal
- Department of Chemistry; Durham University; South Road Durham DH1 3LE UK
| | - Thomas J. Penfold
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
| | - Michael J. Hall
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne NE1 7RU UK
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43
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Reinhard M, Auböck G, Besley NA, Clark IP, Greetham GM, Hanson-Heine MWD, Horvath R, Murphy TS, Penfold TJ, Towrie M, George MW, Chergui M. Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies. J Am Chem Soc 2017; 139:7335-7347. [DOI: 10.1021/jacs.7b02769] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marco Reinhard
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
| | - Gerald Auböck
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
| | - Nicholas A. Besley
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | | | - Raphael Horvath
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Thomas S. Murphy
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Thomas J. Penfold
- School
of Chemistry, Newcastle University, Newcastle upon Tyne NE1
7RU, United Kingdom
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Michael W. George
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
- Department
of Chemical and Environmental Engineering, University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China
| | - Majed Chergui
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
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44
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Etherington MK, Franchello F, Gibson J, Northey T, Santos J, Ward JS, Higginbotham HF, Data P, Kurowska A, Dos Santos PL, Graves DR, Batsanov AS, Dias FB, Bryce MR, Penfold TJ, Monkman AP. Regio- and conformational isomerization critical to design of efficient thermally-activated delayed fluorescence emitters. Nat Commun 2017; 8:14987. [PMID: 28406153 PMCID: PMC5399286 DOI: 10.1038/ncomms14987] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/19/2017] [Indexed: 11/12/2022] Open
Abstract
Regio- and conformational isomerization are fundamental in chemistry, with profound effects upon physical properties, however their role in excited state properties is less developed. Here two regioisomers of bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene-S,S-dioxide, a donor–acceptor–donor (D–A–D) thermally-activated delayed fluorescence (TADF) emitter, are studied. 2,8-bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene-S,S-dioxide exhibits only one quasi-equatorial conformer on both donor sites, with charge-transfer (CT) emission close to the local triplet state leading to efficient TADF via spin-vibronic coupling. However, 3,7-bis(10H-phenothiazin-10-yl)dibenzo[b,d]thiophene-S,S-dioxide displays both a quasi-equatorial CT state and a higher-energy quasi-axial CT state. No TADF is observed in the quasi-axial CT emission. These two CT states link directly to the two folded conformers of phenothiazine. The presence of the low-lying local triplet state of the axial conformer also means that this quasi-axial CT is an effective loss pathway both photophysically and in devices. Importantly, donors or acceptors with more than one conformer have negative repercussions for TADF in organic light-emitting diodes. The search for brighter emitting materials is essential to the development of OLED devices. Etherington et al. show how the presence of two regioisomers of a donor-acceptor-donor thermally-activated delayed fluorescence molecule affects the device efficiency, with one acting as a triplet quencher.
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Affiliation(s)
- Marc K Etherington
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Flavio Franchello
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Jamie Gibson
- School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Thomas Northey
- School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Jose Santos
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
| | - Jonathan S Ward
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
| | | | - Przemyslaw Data
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK.,Faculty of Chemistry, Silesian University of Technology, Marcina Strzody 9, 44-100 Gliwice, Poland
| | - Aleksandra Kurowska
- Faculty of Chemistry, Silesian University of Technology, Marcina Strzody 9, 44-100 Gliwice, Poland
| | | | - David R Graves
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Andrei S Batsanov
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
| | - Fernando B Dias
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Martin R Bryce
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
| | - Thomas J Penfold
- School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Andrew P Monkman
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
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45
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46
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Currie L, Fernandez-Cestau J, Rocchigiani L, Bertrand B, Lancaster SJ, Hughes DL, Duckworth H, Jones STE, Credgington D, Penfold TJ, Bochmann M. Frontispiece: Luminescent Gold(III) Thiolates: Supramolecular Interactions Trigger and Control Switchable Photoemissions from Bimolecular Excited States. Chemistry 2017. [DOI: 10.1002/chem.201780164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Lucy Currie
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
| | | | - Luca Rocchigiani
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
| | - Benoît Bertrand
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
| | - Simon J. Lancaster
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
| | - David L. Hughes
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
| | - Helen Duckworth
- School of Chemistry; Newcastle University; Newcastle upon Tyne NE1 7RU United Kingdom
| | - Saul T. E. Jones
- Department of Physics; Cavendish Laboratory; Cambridge University; Cambridge CB3 0HF United Kingdom
| | - Dan Credgington
- Department of Physics; Cavendish Laboratory; Cambridge University; Cambridge CB3 0HF United Kingdom
| | - Thomas J. Penfold
- School of Chemistry; Newcastle University; Newcastle upon Tyne NE1 7RU United Kingdom
| | - Manfred Bochmann
- School of Chemistry; University of East Anglia; Norwich NR4 7TJ United Kingdom
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47
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Etherington MK, Gibson J, Higginbotham HF, Penfold TJ, Monkman AP. Revealing the spin-vibronic coupling mechanism of thermally activated delayed fluorescence. Nat Commun 2016; 7:13680. [PMID: 27901046 PMCID: PMC5141373 DOI: 10.1038/ncomms13680] [Citation(s) in RCA: 359] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/25/2016] [Indexed: 12/14/2022] Open
Abstract
Knowing the underlying photophysics of thermally activated delayed fluorescence (TADF) allows proper design of high efficiency organic light-emitting diodes. We have proposed a model to describe reverse intersystem crossing (rISC) in donor-acceptor charge transfer molecules, where spin-orbit coupling between singlet and triplet states is mediated by one of the local triplet states of the donor (or acceptor). This second order, vibronically coupled mechanism describes the basic photophysics of TADF. Through a series of measurements, whereby the energy ordering of the charge transfer (CT) excited states and the local triplet are tuned in and out of resonance, we show that TADF reaches a maximum at the resonance point, substantiating our model of rISC. Moreover, using photoinduced absorption, we show how the populations of both singlet and triplet CT states and the local triplet state change in and out of resonance. Our vibronic coupling rISC model is used to predict this behaviour and describes how rISC and TADF are affected by external perturbation.
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Affiliation(s)
- Marc K Etherington
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Jamie Gibson
- School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | | | - Thomas J Penfold
- School of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Andrew P Monkman
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
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48
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Currie L, Fernandez-Cestau J, Rocchigiani L, Bertrand B, Lancaster SJ, Hughes DL, Duckworth H, Jones STE, Credgington D, Penfold TJ, Bochmann M. Luminescent Gold(III) Thiolates: Supramolecular Interactions Trigger and Control Switchable Photoemissions from Bimolecular Excited States. Chemistry 2016; 23:105-113. [PMID: 27859790 PMCID: PMC5215685 DOI: 10.1002/chem.201603841] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Indexed: 11/21/2022]
Abstract
A new family of cyclometallated gold(III) thiolato complexes based on pyrazine‐centred pincer ligands has been prepared, (C^Npz^C)AuSR, where C^Npz^C=2,6‐bis(4‐ButC6H4)pyrazine dianion and R=Ph (1), C6H4tBu‐4 (2), 2‐pyridyl (3), 1‐naphthyl (1‐Np, 4), 2‐Np (5), quinolinyl (Quin, 6), 4‐methylcoumarinyl (Coum, 7) and 1‐adamantyl (8). The complexes were isolated as yellow to red solids in high yields using mild synthetic conditions. The single‐crystal X‐ray structures revealed that the colour of the deep‐red solids is associated with the formation of a particular type of short (3.2–3.3 Å) intermolecular pyrazine⋅⋅⋅pyrazine π‐interactions. In some cases, yellow and red crystal polymorphs were formed; only the latter were emissive at room temperature. Combined NMR and UV/Vis techniques showed that the supramolecular π‐stacking interactions persist in solution and give rise to intense deep‐red photoluminescence. Monomeric molecules show vibronically structured green emissions at low temperature, assigned to ligand‐based 3IL(C^N^C) triplet emissions. By contrast, the unstructured red emissions correlate mainly with a 3LLCT(SR→{(C^Npz^C)2}) charge transfer transition from the thiolate ligand to the π⋅⋅⋅π dimerized pyrazine. Unusually, the π‐interactions can be influenced by sample treatment in solution, such that the emissions can switch reversibly from red to green. To our knowledge this is the first report of aggregation‐enhanced emission in gold(III) chemistry.
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Affiliation(s)
- Lucy Currie
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | | | - Luca Rocchigiani
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - Benoît Bertrand
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - Simon J Lancaster
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - David L Hughes
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - Helen Duckworth
- School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Saul T E Jones
- Department of Physics, Cavendish Laboratory, Cambridge University, Cambridge, CB3 0HF, United Kingdom
| | - Dan Credgington
- Department of Physics, Cavendish Laboratory, Cambridge University, Cambridge, CB3 0HF, United Kingdom
| | - Thomas J Penfold
- School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Manfred Bochmann
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
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49
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Gibson J, Monkman AP, Penfold TJ. The Importance of Vibronic Coupling for Efficient Reverse Intersystem Crossing in Thermally Activated Delayed Fluorescence Molecules. Chemphyschem 2016; 17:2956-2961. [PMID: 27338655 PMCID: PMC5096030 DOI: 10.1002/cphc.201600662] [Citation(s) in RCA: 291] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Indexed: 11/09/2022]
Abstract
Factors influencing the rate of reverse intersystem crossing (krISC ) in thermally activated delayed fluorescence (TADF) emitters are critical for improving the efficiency and performance of third-generation heavy-metal-free organic light-emitting diodes (OLEDs). However, present understanding of the TADF mechanism does not extend far beyond a thermal equilibrium between the lowest singlet and triplet states and consequently research has focused almost exclusively on the energy gap between these two states. Herein, we use a model spin-vibronic Hamiltonian to reveal the crucial role of non-Born-Oppenheimer effects in determining krISC . We demonstrate that vibronic (nonadiabatic) coupling between the lowest local excitation triplet (3 LE) and lowest charge transfer triplet (3 CT) opens the possibility for significant second-order coupling effects and increases krISC by about four orders of magnitude. Crucially, these simulations reveal the dynamical mechanism for highly efficient TADF and opens design routes that go beyond the Born-Oppenheimer approximation for the future development of high-performing systems.
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Affiliation(s)
- Jamie Gibson
- School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | | | - Thomas J Penfold
- School of Chemistry, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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50
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Abstract
Fe(II) complexes have long been assumed unsuitable as photosensitizers because of their low-lying nonemissive metal centered (MC) states, which inhibit electron transfer. Herein, we describe the excited-state relaxation of a novel Fe(II) complex that incorporates N-heterocyclic carbene ligands designed to destabilize the MC states. Using first-principles quantum nuclear wavepacket simulations we achieve a detailed understanding of the photoexcited decay mechanism, demonstrating that it is dominated by an ultrafast intersystem crossing from (1)MLCT-(3)MLCT proceeded by slower kinetics associated with the conversion into the (3)MC states. The slowest component of the (3)MLCT decay, important in the context of photosensitizers, is much longer than related Fe(II) complexes because the population transfer to the (3)MC states occurs in a region of the potential where the energy gap between the (3)MLCT and (3)MC states is large, making the population transfer inefficient.
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Affiliation(s)
- Mátyás Pápai
- Wigner Research Centre for Physics, Hungarian Academy of Sciences , P.O. Box 49, H-1525 Budapest, Hungary
- Department of Chemistry, Technical University of Denmark , DK-2800 Kongens Lyngby, Denmark
| | - György Vankó
- Wigner Research Centre for Physics, Hungarian Academy of Sciences , P.O. Box 49, H-1525 Budapest, Hungary
| | - Tamás Rozgonyi
- Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , P.O. Box 286, H-1519 Budapest, Hungary
| | - Thomas J Penfold
- School of Chemistry, Newcastle University , Newcastle upon Tyne NE1 7RU, United Kingdom
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