Ultrafast dynamics of excitons in tetracene single crystals

Birech, Zephania; Schwoerer, M.; Schmeiler, Teresa; Pflaum, Jens; Schwoerer, H.

doi:10.1063/1.4867696

Cited by 43 publications

(53 citation statements)

References 51 publications

(97 reference statements)

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“…When we compare these decays, we see that they nearly overlap during the first ≈5 ns, after which they start to diverge quickly over a time period of ≈50 ns. To better describe the dynamics of the excited states of the tetracene crystal and to understand what may be the cause of the difference in TRPL, we have used a kinetic model to describe the time evolution of the different states . To simplify the model and limit the number of fitting parameters, we did not consider the different spin states of the triplet pair as separate states, but they are all included in the triplet pair state.…”

Section: Excited State Dynamics Of Bare and Strongly Coupled Tetracenmentioning

confidence: 99%

Enhanced Delayed Fluorescence in Tetracene Crystals by Strong Light‐Matter Coupling

Berghuis

Halpin

Le‐Van

et al. 2019

Adv Funct Materials

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An enhanced delayed fluorescence is demonstrated experimentally in tetracene single crystals strongly coupled to optical modes in open cavities formed by arrays of plasmonic nanoparticles. Hybridization of singlet excitons with collective plasmonic resonances in the arrays leads to the splitting of the material dispersion into a lower and an upper polariton band. This splitting significantly modifies the dynamics of the photoexcited tetracene crystal, resulting in an increase of the delayed fluorescence by a factor of 4. The enhanced delayed fluorescence is attributed to the emergence of an additional radiative decay channel, where the lower polariton band harvests long-lived triplet states. There is also an increase in total emission, which is wavelength dependent, and can be explained by the direct emission from the lower polariton band, the more efficient light out-coupling, and the enhancement of the excitation intensity. The observed enhanced fluorescence opens the possibility of efficient radiative triplet harvesting in open optical cavities, to improve the performance of organic light emitting diodes. and organic photovoltaics (OPV). The performance of these devices is determined by properties such as absorption and emission cross-section, chemical reactivity, and excited state dynamics, arising from the potential energy surface of the molecules. [1,2] Hence, controlling the energy surface can provide a remarkable impact on photophysical processes involved in these devices. Tuning of the properties of organic materials is usually done through chemical synthesis. However, changing the molecular composition might also affect the processability and morphology of thin films fabricated from the molecules, which may be detrimental for the performance.Recently, an alternative method has emerged to modify the energy surfaces of molecules and to alter their properties without changing the molecular composition: strong light-matter coupling. Theoretical developments continue to uncover the physics underpinning changes to the potential energy surfaces of molecules in this regime, [3][4][5] with tremendous implications for the photophysical properties of organic materials. Strong coupling between photons in optical cavities and excitons in semiconductors results in hybrid quasi-particles called exciton-polaritons. The strong coupling leads to an avoided crossing between the dispersions of cavity photons and excitons at the energy and momentum at which they would overlap. This coupling leads to the splitting in energy of the dispersion into the lower polariton band (LPB) and the upper polariton band (UPB). The width of the splitting between these bands is determined by the coupling strength and is called the Rabi energy. The properties of these hybrid quasi-particles are a combination of the properties of the two uncoupled states (bare states). [6] This remarkable consequence of strong coupling has led to the possibility of tuning the properties of materials, such as exciton transport, [7][8][9][10] conductivity, [11] ...

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Section: Excited State Dynamics Of Bare and Strongly Coupled Tetracenmentioning

confidence: 99%

Enhanced Delayed Fluorescence in Tetracene Crystals by Strong Light‐Matter Coupling

Berghuis

Halpin

Le‐Van

et al. 2019

Adv Funct Materials

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“…The reconstructed triplet signal is proportional to the total density of paired and unpaired triplet excitons, i.e., ) ( Among the latest reports, the value of SF rate is below that estimated at higher density in Birech's work 38 but slightly above the values reported under weaker excitations. 12,22 Two possible reasons may cause such slight divergences.…”

mentioning

confidence: 92%

“…The PIA band is probably induced by ESA associated with the transitions of S → S . 12,23,38 The polarization dependence is related to the dipole alignment which depends on the symmetry of S and S states. Considering the complexity of S states, the ESA shows a different polarization dependence from PIB in the spectral range of 2.2-2.3 eV (Fig.…”

Section: 23mentioning

confidence: 99%

“…52,53 However, this effect has rarely been considered in the available studies on SF dynamics. 38,40 Here, we report a systematic study on the anisotropic exciton dynamics in tetracene single crystals with polarization-dependent transient absorption (TA) spectroscopy. The spectrotemporal characteristics for singlet and triplet excitons are observed to be strongly dependent on probe polarization.…”

Section: Introductionmentioning

confidence: 99%

“…9,10,12,14,17,18,22,29,30,[38][39][40][41][42][43][44][45] In crystalline tetracene, SF is very efficient although it is a slightly endothermic process. In the latest studies on tetracene with transient optical spectroscopy, the fission rate has been characterized 9,12,14,17,23 and an intermediate multiexciton state has been identified to mediate the SF process.…”

Section: Introductionmentioning

confidence: 99%

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Polarization-dependent exciton dynamics in tetracene single crystals

Zhang

et al. 2014

The Journal of Chemical Physics

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Abstract:We conduct polarization-dependent ultrafast spectroscopy to study the dynamics of singlet fission in tetracene single crystals. The spectrotemporal species for singlet and triplet excitons in transient absorption spectra are found to be strongly dependent on probe polarization. By carefully analyzing the polarization dependence, the signals contributed by different transitions related to singlet excitons have been disentangled, which is further applied to construct the correlation between dynamics of singlet and triplet excitons. The anisotropy of exciton dynamics provides an alternative approach to tackle the long-standing challenge in understanding the mechanism of singlet fission in organic semiconductors.

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Electronic Structure and Dynamics of Singlet Fission in Organic Molecules and Crystals

Berkelbach

2017

Advances in Chemical Physics

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Ultrafast dynamics of excitons in tetracene single crystals

Cited by 43 publications

References 51 publications

Enhanced Delayed Fluorescence in Tetracene Crystals by Strong Light‐Matter Coupling

Enhanced Delayed Fluorescence in Tetracene Crystals by Strong Light‐Matter Coupling

Polarization-dependent exciton dynamics in tetracene single crystals

Electronic Structure and Dynamics of Singlet Fission in Organic Molecules and Crystals

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