Density of states of the lowest exciton band and the exciton bandwidth in coronene single crystals

Totoki, R.; Aoki-Matsumoto, Tamao; Mizuno, Ken-ichi

doi:10.1016/j.jlumin.2004.09.096

Cited by 9 publications

(8 citation statements)

References 5 publications

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“…As shown in ref., the range of the averaged relative dielectric constant of the molecular semiconductors is mainly in the interval of 2.55–3.34. Considering the mean value of this range (i.e., 2.95) leads to a median bandwidth 0.32 eV and an interquartile range 0.27 eV (Supporting Information Figure S4), which are in excellent agreement with the values reported in refs. ,− Furthermore, the attained maximum bandwidth 1.16 eV (considering the top 5% of the data) is in conformity with the theoretical calculations and experimental measurements reported, e.g., in refs. ,, and clearly the extreme cases are simply a reflection of the larger data set considered.…”

Section: Resultssupporting

confidence: 89%

Bright Frenkel Excitons in Molecular Crystals: A Survey

2021

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We computed the optical properties of a large set of molecular crystals (∼2200 structures) composed of molecules whose lowest excited states are strongly coupled and generate wide excitonic bands. Such bands are classified in terms of their dimensionality (1-, 2-, and 3-dimensional), the position of the optically allowed state in relation with the excitonic density of states, and the presence of Davydov splitting. The survey confirms that one-dimensional aggregates are rare in molecular crystals highlighting the need to go beyond the simple low-dimensional models. Furthermore, this large set of data is used to search for technologically interesting and less common properties. For instance, we considered the largest excitonic bandwidth that is achievable within known molecular crystals and identified materials with strong super-radiant states. Finally, we explored the possibility that strong excitonic coupling can be used to generate emissive states in the near-infrared region in materials formed by molecules with bright visible absorption and we could identify the maximum allowable red shift in this material class. These insights with the associated searchable database provide practical guidelines for designing materials with interesting optical properties.

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Section: Resultssupporting

confidence: 89%

Bright Frenkel Excitons in Molecular Crystals: A Survey

2021

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“…13 Pure coronene possesses monoclinic symmetry with two molecules per unit cell, the space group P2 1 /a and lattice parameters: a = 16.094(9) Å, b = 4.690(3) Å, c = 10.049(8) Å, β = 110.792(2) • . It has been established 14,15 that the dramatic change of its polarized luminescence spectra indicates a temperature-induced phase transition in the temperature range from 140 K to 180 K and another structural phase transition at 50 K. 16 In addition, a reversible phase transition between 2.0 and 3.2 GPa at room temperature was observed from Fourier-Transform Infrared spectroscopy experiments. 17 In a prior study, electron-intramolecular-phonon coupling and its role in the occurrence of possible superconductivity in the monoanions of coronene have been studied.…”

Section: Introductionmentioning

confidence: 97%

Phase transformations and vibrational properties of coronene under pressure

Zhao

Zhang

Berlie

et al. 2013

The Journal of Chemical Physics

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Both the vibrational and structural properties of coronene have been investigated upon compression up to 30.5 GPa at room temperature by a combination of Raman scattering and synchrotron x-ray diffraction measurements. The spectroscopic and crystallographic results demonstrate that two pressure-induced structural phase transitions take place at 1.5 GPa and 12.2 GPa where the high-pressure phases are identified as monoclinic and orthorhombic crystal structures with space groups of P2/m and Pmmm, respectively. A kink in the slope of the cell parameters as a function of pressure is associated with the disappearance of several internal Raman modes, which suggests the existence of structural distortions or reorganizations at approximately 6.0 GPa. Above 17.1 GPa, almost no evidence of crystallinity can be observed, indicating a possible transformation of coronene into an amorphous phase.

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“…1) which is typical for many aromatic molecular solids. Furthermore, coronene crystals show two structural phase transitions depending on pressure and temperature in the range between 140-180 K 32,33 and at 50 K. 34 In this contribution we report on an investigation of the electronic properties of undoped and potassium doped coronene using electron energy-loss spectroscopy (EELS). EELS studies of other undoped and doped molecular materials in the past have provided useful insight into their electronic properties.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of undoped and potassium-doped coronene investigated by electron energy-loss spectroscopy

et al. 2012

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We performed electron energy-loss spectroscopy studies in transmission in order to obtain insight into the electronic properties of potassium intercalated coronene, a recently discovered superconductor with a rather high transition temperature of about 15 K. A comparison of the loss function of undoped and potassium intercalated coronene shows the appearance of several new peaks in the optical gap upon potassium addition. Furthermore, our core level excitation data clearly signal filling of the conduction bands with electrons.

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Density of states of the lowest exciton band and the exciton bandwidth in coronene single crystals

Cited by 9 publications

References 5 publications

Bright Frenkel Excitons in Molecular Crystals: A Survey

Bright Frenkel Excitons in Molecular Crystals: A Survey

Phase transformations and vibrational properties of coronene under pressure

Electronic structure of undoped and potassium-doped coronene investigated by electron energy-loss spectroscopy

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