Fromage: A Library for the Study of Molecular Crystal Excited States at the Aggregate Scale

Rivera, Miguel N.; Dommett, Michael; Sidat, Amir; Rahim, Warda; Crespo‐Otero, Rachel

doi:10.26434/chemrxiv.9786041

Cited by 3 publications

(3 citation statements)

References 39 publications

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“…The excited states in the molecular crystals were simulated using cluster models applying the ONIOM(QM:QM') embedding formalism (OEC) implemented in fromage. 18,19 The QM region included either one or two molecules with the energies evaluated at the TD-ωB97X-D/6-311++G(d,p) level of theory with electrostatic embedding. For the models with monomers in the QM region, the geometries were obtained at the same level of theory, while for the dimers the geometries were optimised with TD-ωB97X-D/6-31G(d).…”

Section: Computational Detailsmentioning

confidence: 99%

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Competition between ultralong organic phosphorescence and thermally activated delayed fluorescence in dichloro derivatives of 9-benzoylcarbazole

Sidat

Hernández

Stojanović

et al. 2022

Preprint

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Optoelectronic materials based on metal-free organic molecules represent a promising alternative to traditional inorganic devices. Significant attention has been devoted to the development of the third generation of OLEDs which are based on the temperature-activated delayed fluorescence (TADF) mechanism. In the last few years, several materials displaying ultra-long organic phosphorescence (UOP) have been designed using strategies such as crystal engineering and halogen functionalisation. Both TADF and UOP are controlled by the population of triplet states and the energy gaps between the singlet and triplet manifolds. In this paper, we explore the competition between TADF and UOP in the molecular crystals of three dichloro derivatives of 9H-carbazol-3-yl(phenyl)methanone. We investigate the excited state mechanisms in solution and the crystalline phase and address the effects of exciton transport and temperature on the rates of direct and reverse intersystem crossing under the Marcus-Levich-Jortner model. We also analyse how the presence of isomeric impurities and the stabilisation of charge transfer states affect these processes. Our simulations explain the different mechanisms observed for the three derivatives and highlight the role of intramolecular rotation and crystal packing in determining the energy gaps. This work contributes to a better understanding of the connection between chemical and crystalline structures that will enable the design of efficient materials.

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Section: Computational Detailsmentioning

confidence: 99%

“…S7-S9, Table S9). 19 Table S9 shows the excited state properties of all dimers, Table 3 highlights the dimers with exciton couplings larger than 7 meV.…”

Section: Crystal Packing and Intermolecular Interactionsmentioning

confidence: 99%

Competition between ultralong organic phosphorescence and thermally activated delayed fluorescence in dichloro derivatives of 9-benzoylcarbazole

Sidat

Hernández

Stojanović

et al. 2022

Preprint

Self Cite

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“…The effect of the polarization of the environment was considered for both methods within a self-consistent embedding algorithm. These approaches were implemented in fromage; the source code and the documentation are available online. , …”

Section: Embedding Schemesmentioning

confidence: 99%

ONIOM(QM:QM′) Electrostatic Embedding Schemes for Photochemistry in Molecular Crystals

Rivera

Dommett

Crespo‐Otero

2019

J. Chem. Theory Comput.

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Understanding photoinduced processes in molecular crystals is central to the design of highly emissive materials such as organic lasers and organic light-emitting diodes. The modelling of such processes is, however, hindered by the lack of excited state methodologies tailored for these systems. Embedding approaches based on the Ewald sum can be used in conjunction with excited state electronic structure methods to model the localised excitations which characterise these materials. In this article, we describe the implementation of a two-level ONIOM(QM:QM') point charge embedding approach based on the Ewald method, the ONIOM Ewald Embedded Cluster (OEEC) model. An alternative self-consistent method is also considered to simulate the response of the environment to the excitation. Two molecular crystals with opposing photochemical behaviour were used to benchmark the results with single reference and multireference methods. We observed that the inclusion of an explicit ground state cluster surrounding the QM region was imperative for the exploration of the excited state potential energy surfaces. Using OEEC, accurate absorption and emission energies as well as S 1-S 0 conical intersections were obtained for both crystals. We discuss the implications of the use of these embedding schemes considering the degree of localisation of the excitation. The methods discussed herein are implemented in an open source platform (fromage, https://github.com/Crespo-Otero-group/fromage) which acts as an interface between popular electronic structure codes (Gaussian, Turbomole and Molcas).

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Emission Quenching in Tetraphenylfuran Crystal: Why This Propeller-Shaped Molecule Does Not Emit in the Condensed Phase

Stojanović

Crespo‐Otero

2022

Molecules

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Due to their substantial fluorescence quantum yields in the crystalline phase, propeller-shaped molecules have recently gained significant attention as potential emissive materials for optoelectronic applications. For the family of cyclopentadiene derivatives, light-emission is highly dependent on the nature of heteroatomic substitutions. In this paper, we investigate excited state relaxation pathways in the tetraphenyl-furan molecule (TPF), which in contrast with other molecules in the family, shows emission quenching in the solid-state. For the singlet manifold, our calculations show nonradiative pathways associated with C-O elongation are blocked in both vacuum and the solid state. A fraction of the population can be transferred to the triplet manifold and, subsequently, to the ground state in both phases. This process is expected to be relatively slow due to the small spin-orbit couplings between the relevant singlet-triplet states. Emission quenching in crystalline TPF seems to be in line with more efficient exciton hopping rates. Our simulations help clarify the role of conical intersections, population of the triplet states and crystalline structure in the emissive response of propeller-shaped molecules.

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Fromage: A Library for the Study of Molecular Crystal Excited States at the Aggregate Scale

Cited by 3 publications

References 39 publications

Competition between ultralong organic phosphorescence and thermally activated delayed fluorescence in dichloro derivatives of 9-benzoylcarbazole

Competition between ultralong organic phosphorescence and thermally activated delayed fluorescence in dichloro derivatives of 9-benzoylcarbazole

ONIOM(QM:QM′) Electrostatic Embedding Schemes for Photochemistry in Molecular Crystals

Emission Quenching in Tetraphenylfuran Crystal: Why This Propeller-Shaped Molecule Does Not Emit in the Condensed Phase

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