The entangled triplet pair state in acene and heteroacene materials

Yong, Chaw-Keong; Musser, Andrew J.; Bayliss, Sam L.; Lukman, Steven; Tamura, Hiroyuki; Bubnova, Olga; Hallani, Rawad K.; Meneau, Aurélie; Resel, Roland; Maruyama, Munetaka; Hotta, Shu; Herz, Laura M.; Beljonne, David; Anthony, John E.; Clark, Jenny; Sirringhaus, Henning

doi:10.1038/ncomms15953

Cited by 195 publications

(421 citation statements)

References 75 publications

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“…As the annihilation of two free triplets to a singlet depends on the probability of two triplets to interact, this rate scales quadratically with the number of excitons and therefore with the excitation intensity . Free triplet annihilation is the main origin of the delayed fluorescence from tetracene on time scales longer than 10 ns …”

Section: Excited State Dynamics Of Bare and Strongly Coupled Tetracensupporting

confidence: 78%

“…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. The model is given by the following rate equations

\frac{d N_{normalS}}{d t} = - (k_{normalS} + k_{fis}) N_{normalS} - k_{SSA} N_{normalS}^{2} + k_{fus} N_{TTpair}

\frac{d N_{TTpair}}{d t} = - (k_{TTpair} + k_{fus} + k_{PF}) N_{TTpair} + k_{fis} N_{normalS} + k_{FP} N_{Tfree}^{2}

\frac{d N_{Tfree}}{d t} = - k_{Tfree} N_{Tfree} - 2 k_{FP} N_{Tfree}^{2} + 2 k_{PF} N_{TTpair}

…”

Section: Excited State Dynamics Of Bare and Strongly Coupled Tetracenmentioning

confidence: 99%

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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 Tetracensupporting

confidence: 78%

\frac{d N_{normalS}}{d t} = - (k_{normalS} + k_{fis}) N_{normalS} - k_{SSA} N_{normalS}^{2} + k_{fus} N_{TTpair}

\frac{d N_{TTpair}}{d t} = - (k_{TTpair} + k_{fus} + k_{PF}) N_{TTpair} + k_{fis} N_{normalS} + k_{FP} N_{Tfree}^{2}

\frac{d N_{Tfree}}{d t} = - k_{Tfree} N_{Tfree} - 2 k_{FP} N_{Tfree}^{2} + 2 k_{PF} N_{TTpair}

…”

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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“…This is a critical distinction from inorganic excitonpolaritons that has not yet been addressed in the literature. The existence of this state mixing is a critical driver in photophysical processes such as ultrafast intersystem crossing 45 , thermally activated delayed fluorescence 46 , singlet exciton fission 42,44 and its reverse, triplet-triplet annihilation. For example, in singlet fission the nominal S1 state contains both CT and TT character, in some cases such as pentacene films to a surprisingly high degree (circa 50% CT) 47 .…”

Section: Discussionmentioning

confidence: 99%

Manipulating molecules with strong coupling: harvesting triplet excitons in organic exciton microcavities

et al. 2020

Self Cite

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Exciton-polaritons are quasiparticles with mixed photon and exciton character that demonstrate rich quantum phenomena, novel optoelectronic devices and the potential to modify chemical properties of materials. Organic semiconductors are of current interest for their room-temperature polariton formation. However, within organic optoelectronic devices, it is often the 'dark' spin-1 triplet excitons that dominate operation. These triplets have been largely ignored in treatments of polariton physics. Here we demonstrate polariton population from the triplet manifold via triplettriplet annihilation, leading to polariton emission that is longer-lived (>μs) even than exciton emission in bare films. This enhancement arises from spin-2 triplet-pair states, formed by singlet fission or triplet-triplet annihilation, feeding the polariton. This is possible due to state mixing, which -in the strong coupling regime-leads to sharing of photonic character with states that are formally non-emissive. Such 'photonic sharing' offers the enticing possibility of harvesting or manipulating even states that are formally dark.

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“…However, the TA and TE were not observed on the PTPB (Figure f), despite the existence of triplet states with longer lifetime. Triplet excimer has been observed in other chromophores of close intermolecular distance or intramolecular linkers, where two molecules in triplet states participate in a cooperative absorption and emission . The close packing of TTMA molecules in TPB is likely to form the triplet excimers exhibiting the TA and TE, while this is prohibited in PTPB where TTMA is separated by nonactive PEA molecules.…”

mentioning

confidence: 99%

Efficient Room‐Temperature Phosphorescence from Organic–Inorganic Hybrid Perovskites by Molecular Engineering

et al. 2018

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Solution-processed organic-inorganic hybrid perovskites are promising emitters for next-generation optoelectronic devices. Multiple-colored, bright light emission is achieved by tuning their composition and structures. However, there is very little research on exploring optically active organic cations for hybrid perovskites. Here, unique room-temperature phosphorescence from hybrid perovskites is reported by employing novel organic cations. Efficient room-temperature phosphorescence is activated by designing a mixed-cation perovskite system to suppress nonradiative recombination. Multiple-colored phosphorescence is achieved by molecular design. Moreover, the emission lifetime can be tuned by varying the perovskite composition to achieve persistent luminescence. Efficient room-temperature phosphorescence is demonstrated in hybrid perovskites that originates from the triplet states of the organic cations, opening a new dimension to the further development of perovskite emitters with novel functional organic cations for versatile display applications.

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The entangled triplet pair state in acene and heteroacene materials

Cited by 195 publications

References 75 publications

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

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

Manipulating molecules with strong coupling: harvesting triplet excitons in organic exciton microcavities

Efficient Room‐Temperature Phosphorescence from Organic–Inorganic Hybrid Perovskites by Molecular Engineering

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