Donor–acceptor molecular aggregates: Vibronic spectra of mixed Frenkel and charge-transfer excitons

Warns, Ch.; Lalov, I. J.; Reineker, P.

doi:10.1016/j.jlumin.2008.12.025

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…In this study, we examine the characteristics and formation mechanism of Fabry–Perot interference fringes in the suboptical gap light emission spectra of the perovskite-like layered material hexyl ammonium lead iodide (HA 2 PbI 4 ) and 1:1 cocrystals of anthracene and pyromellitic dianhydride (A-PMDA). The ability to process semiconducting hybrid organic–inorganic perovskite in solution gives them the potential to transform methods to fabricate optoelectronic technologies including photovoltaic cells, ,,, light-emitting diodes, ,, and lasers. ,, A-PMDA has long been used as a model system to understand the properties of charge-transfer (CT) excitons including fine structure and their coupling to material vibrations. − The ability to reliably control the light emitted by this material may open interesting avenues to interrogate intermolecular interactions in the solid state.…”

Section: Introductionmentioning

confidence: 99%

Probing Fabry–Perot Interference in Self-Assembled Excitonic Microcrystals with Subgap Light Emission

2019

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Establishing a fundamental understanding of the range of optical effects possible in self-assembled excitonic materials remains crucial to the utility of these materials in future optoelectronic and photonic technologies. In this study, we report the observation and subsequent analysis of Fabry–Perot interference intrinsic to two types of self-assembled excitonic crystalline materials: the hybrid organic–inorganic perovskite-like quantum well superlattice structure of hexyl ammonium lead iodide and the charge-transfer cocrystal of anthracene and pyromellitic dianhydride. The observation of Fabry–Perot interference stems from strong suboptical gap photoluminescence (PL) from both materials in a spectral region of very low material absorption. We characterize this subgap PL in each material to propose permanent defect trap excitons, stabilize their energy, and cause subgap light emission in both materials. We use a model developed to explain interference in the photoluminescence of vacuum-deposited thin films to estimate the thickness, mid-bandgap index of refraction, and surface roughness of our samples. These results indicate that self-assembled excitonic materials may have use in applications such as laser amplifiers, frequency discriminators, and single photon emitters.

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Section: Introductionmentioning

confidence: 99%

Probing Fabry–Perot Interference in Self-Assembled Excitonic Microcrystals with Subgap Light Emission

2019

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“…The complicated interplay between intermolecular excitation transfer interactions, disorder, and coupling to vibrations and its effect on spectral and energy transport properties have been topics continuously attracting attention throughout the history of research on molecular aggregates [34,35]. Historic examples are the formation of vibronic excitations and corresponding spectral bands and dynamics [36][37][38][39][40], as well as the destruction of exciton superradiance with rising temperature [17,41]. A well-known recent example concerns the coherence of excitons in lightharvesting antenna complexes, such as FMO, and its contribution to the excitation transport efficiency in these systems [42][43][44][45][46][47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

Vibronic effects and destruction of exciton coherence in optical spectra of J-aggregates: A variational polaron transformation approach

et al. 2016

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Using a symmetry adapted polaron transformation of the Holstein Hamiltonian, we study the interplay of electronic excitation-vibration couplings, resonance excitation transfer interactions, and temperature in the linear absorption spectra of molecular J-aggregates. Semi-analytical expressions for the spectra are derived and compared with results obtained from direct numerical diagonalization of the Hamiltonian in the two-particle basis set representation. At zero temperature, we show that our polaron transformation reproduces both the collective (exciton) and single-molecule (vibrational) optical response associated with the appropriate standard perturbation limits. Specifically, for the molecular dimer excellent agreement with the spectra from the two-particle approach for the entire range of model parameters is obtained. This is in marked contrast to commonly used polaron transformations. Upon increasing the temperature, the spectra show a transition from the collective to the individual molecular features, which results from the thermal destruction of the exciton coherence.

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“…Yet, the investigation of hexagonal 2D molecular crystal structures began several decades ago with the purple membrane of bacteriorhodopsin. − We also refer to an example of successful engineering of a hexagonal quasi-2D crystal. In previous papers, − we have considered theoretically the vibronic spectra of Frenkel and charge-transfer excitons in linear and 2D structures, simulating in this way mono- and triclinic molecular crystals. − In the present paper, we apply also the concept of Frenkel excitons (FEs) − to a 2D monolayer of graphene symmetry with two identical but not equivalently positioned molecules per unit cell (see Figure ). The hexagonal graphene-like honeycomb lattice consists of two interpenetrating trigonal lattices.…”

Section: Introductionmentioning

confidence: 99%

Excitonic and Vibronic Spectra of a Two-Dimensional Graphene-like Molecular Lattice

2020

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Recently, graphene has shown interesting physical properties with promising applications. In this paper, we study the excitonic and vibronic spectra of Frenkel excitons (FEs) in a two-dimensional hexagonal graphene-like lattice with two identical and nonequivalently positioned molecules per unit cell. The excitonic Hamiltonian and the excitonic levels with transition dipole moments perpendicular to the layer or parallel to it represent the electronic excitations of this hexagonal lattice. The vibronic spectra consist of both types of dipole active FEs plus one or several quanta of intramolecular vibrations coupled with FEs via linear and quadratic coupling. The expressions and numerical simulations of the absorption spectra manifest excitonic, one-particle (bound), and many-particle unbound exciton–phonon states depending on the strength of the linear exciton–phonon coupling as well as Davydov splitting of the vibronic spectra.

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Donor–acceptor molecular aggregates: Vibronic spectra of mixed Frenkel and charge-transfer excitons

Cited by 5 publications

References 15 publications

Probing Fabry–Perot Interference in Self-Assembled Excitonic Microcrystals with Subgap Light Emission

Probing Fabry–Perot Interference in Self-Assembled Excitonic Microcrystals with Subgap Light Emission

Vibronic effects and destruction of exciton coherence in optical spectra of J-aggregates: A variational polaron transformation approach

Excitonic and Vibronic Spectra of a Two-Dimensional Graphene-like Molecular Lattice

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