Relaxation dynamics into two types of luminescence states in C60 single crystals below 80 K

Akimoto, Ikuko; Azuma, Junpei; Ashida, Masaaki; Kan'no, K.

doi:10.1016/s0022-2313(97)00201-9

Cited by 12 publications

(4 citation statements)

References 5 publications

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“…55 The fluorescence spectra for isolated C 60 suggest that the origin of the S 0 → S 1 transition is about 1.94 eV; 57 in the solid state, this value reduces to about 1.7 eV. 58 BLYP underestimates the energy of S 1 in both systems, while B3LYP underestimates it for pentacene and agrees reasonably well with the experimental result for C 60 . Without tuning of the range-separation parameter, the LRC functionals significantly overestimate the S 0 →S 1 transition for both molecules.…”

Section: Resultssupporting

confidence: 54%

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Zhang

Sears

Yang

et al. 2014

J. Chem. Theory Comput.

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The characteristics of the electronic excited states and the charge-transfer processes at organic-organic interfaces play an important role in organic electronic devices. However, charge-transfer excitations have proven challenging to describe with conventional density functional theory (DFT) methodologies due to the local nature of the exchange-correlation potentials often employed. Here, we examine the excited states of model pentacene-C60 complexes using time-dependent DFT with, on one hand, one of the most popular standard hybrid functionals (B3LYP) and, on the other hand, several long-range corrected hybrid functionals for which we consider both default and nonempirically tuned range-separation parameters. The DFT results based on the tuned functionals are found to agree well with the available experimental data. The results also underline that the interface geometry of the complex has a strong effect on the energies and ordering of the singlet and triplet charge-transfer states.

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Section: Resultssupporting

confidence: 54%

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Zhang

Sears

Yang

et al. 2014

J. Chem. Theory Comput.

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“…1.94 eV; 42 in the solid state, this value reduces to 1.7 eV. 43 The TDDFT energies are in good agreement with experiment in the case of pentacene but somewhat higher than the experimental values in the case of C 60 . As in the case of the molecular orbital energies, there are only very small differences between the DFT/ω(vac) and DFT/ω(vac)/PCM estimates, whereas significant modifications occur when going to the DFT/ω(PCM)/PCM level.…”

supporting

confidence: 59%

Description of the Charge Transfer States at the Pentacene/C₆₀ Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

Zheng

Brédas

Coropceanu

2016

J. Phys. Chem. Lett.

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Density functional theory (DFT) approaches based on range-separated hybrid functionals are currently methods of choice for the description of the charge-transfer (CT) states in organic donor/acceptor solar cells. However, these calculations are usually performed on small-size donor/acceptor complexes and as result do not account for electronic polarization effects. Here, using a pentacene/C60 complex as a model system, we discuss the ability of long-range corrected (LCR) hybrid functionals in combination with the polarizable continuum model (PCM) to determine the impact of the solid-state environment on the CT states. The CT energies are found to be insensitive to the interactions with the dielectric medium when a conventional time-dependent DFT/PCM (TDDFT/PCM) approach is used. However, a decrease in the energy of the CT state in the framework of LRC functionals can be obtained by using a smaller range-separated parameter when going from an isolated donor/acceptor complex to the solid-state case.

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“…The absence of any C 60 emission in highly crystalline regions suggests that in these regions the lowest singlet transitions are still parity-forbidden like in an isolated C 60 molecule; thus, most of the singlet excitons may undergo an intersystem crossing to triplet excitons or may be quenched by diffusion to the metal substrate, instead of recombining radiatively at the emission center. However, if the generated singlet excitons are able to diffuse within their lifetime (∼0.7 ns , ) to a structural defect of sufficient ungerade character of the exciton wave function, their radiative recombination is substantially enhanced. Additionally, the trapping of excitons might hamper their diffusion to the substrate and reduce their nonradiative decay channels.…”

Section: Resultsmentioning

confidence: 99%

Submolecular Electroluminescence Mapping of Organic Semiconductors

et al. 2017

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The electroluminescence of organic films is the central aspect in organic light emitting diodes (OLEDs) and widely used in current display technology. However, its spatial variation on the molecular scale is essentially unexplored. Here, we address this issue by using scanning tunneling microscopy (STM) and present an in-depth study of the electroluminescence from thin C films (<10 monolayers) on Ag(111) and Au(111) surfaces. Similar to an OLED, the metal substrate and STM tip inject complementary charge carriers that may recombine within the molecular film; however, the atomically defined charge injection by the tip enables mapping of the local electroluminescence down to the submolecular scale. We show that the radiative recombination in solid C is restricted to various structural defects, whose emission characteristics can be addressed individually. The emission fine structure reveals a coupling to Jahn-Teller active vibrational modes of C, which implies that its parity-forbidden lowest singlet transition becomes locally allowed at the emission centers. At lateral distances of a few nanometers, only a weak emission from tip-induced plasmons is detectable. Their excitation evidences the injection of both charge carrier types and confirms that they are unable to recombine radiatively at positions far from structural defects. Finally, we demonstrate that the molecular orbital pattern visible in electroluminescence maps enables an unambiguous discrimination between the intrinsic radiative recombination of electron-hole pairs in the organic film and the technique-related emission of tip-induced plasmons. This capability is essential to consolidate STM as a tool to explore the light generation from organic films on the nanoscale.

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Relaxation dynamics into two types of luminescence states in C60 single crystals below 80 K

Cited by 12 publications

References 5 publications

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Description of the Charge Transfer States at the Pentacene/C₆₀ Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

Submolecular Electroluminescence Mapping of Organic Semiconductors

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Relaxation dynamics into two types of luminescence states in C60 single crystals below 80 K

Cited by 12 publications

References 5 publications

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C60 Using Tuned Range-Separated Hybrid Functionals

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C60 Using Tuned Range-Separated Hybrid Functionals

Description of the Charge Transfer States at the Pentacene/C60 Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

Submolecular Electroluminescence Mapping of Organic Semiconductors

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Product

Resources

About

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Theoretical Study of the Local and Charge-Transfer Excitations in Model Complexes of Pentacene-C₆₀ Using Tuned Range-Separated Hybrid Functionals

Description of the Charge Transfer States at the Pentacene/C₆₀ Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model