Strong exciton—photon coupling in anthradithiophene microcavities: from isolated molecules to aggregates

Schenck, Jonathan D. B. Van; Tanyi, E. K.; Cheng, Li-Jing; Anthony, John E.; Ostroverkhova, Oksana

doi:10.1557/mrc.2019.101

Cited by 6 publications

(21 citation statements)

References 30 publications

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“…In this case, in C samples, only a subset of a general population of degrading molecules seen in T samples, which is more conducive to photodimerization, would be observed by measuring polariton properties of Figures 6 and 7. In our previous work on functionalized anthradithiophene-and pentacene-based polycrystalline films in cavities, 18,47 we have observed preferential cavity coupling to particular molecular populations (namely, to amorphous phases in the mixed-phase films with coexisting amorphous and crystalline domains). The TIPS-Tc films in the present study, however, are amorphous, and so a preferential cavity coupling to domains with a particular local nanoenvironment conducive for photodimerization would be harder to envision, although it cannot be excluded.…”

Section: Discussionmentioning

confidence: 86%

“…All three exciton transitions (0−0, 0−1, and 0−2) within the S 0 -S 1 absorption band of the TIPS-Tc film coupled to the cavity photon creating the LP, two middle polariton (MP1 and MP2), and the upper polariton (UP) branches (Figures 5b and S12), with the coupling strengths (2V 0i , i = 0,1,2), extracted from fits to the coupled oscillator model (see the SI), scaling as expected with the oscillator strength 40 (Figure S13) and exhibiting values of up to ∼290 meV (Table S3). 18 Because of the similarity between the T and C samples in terms of oxygen availability, we expect that in the cavities (C samples) the photodegradation processes are similar to those discussed above for the T samples, and therefore, we examined the photodimerization of TIPS-Tc molecules in cavities side by side with those in the T samples under the same irradiation conditions.…”

Section: Photodegradation Of Tips-tcmentioning

confidence: 99%

“…Functionalized acenes have served as model systems for a variety of studies of exciton and charge carrier dynamics, and they are among the highest-performing organic semiconductors to date . Strong exciton–photon coupling in various acene crystals and films placed in microcavities has also been observed, − and polariton lasing was demonstrated . A representative of this class is 5,12-bis(triisopropylsilyl)ethynyl tetracene (TIPS-Tc, inset of Figure ) which has been extensively studied as a singlet fission material. − (Singlet fission is a process of generating two triplet states from a singlet exciton, providing a route to boost the efficiency of organic solar cells …”

Section: Introductionmentioning

confidence: 99%

“…A representative of this class is 5,12-bis(triisopropylsilyl)ethynyl tetracene (TIPS-Tc, inset of Figure ) which has been extensively studied as a singlet fission material. − (Singlet fission is a process of generating two triplet states from a singlet exciton, providing a route to boost the efficiency of organic solar cells − TIPS-Tc films placed in microcavities exhibit polariton formation because of strong coupling of excitons in the TIPS-Tc to the cavity photon . A notable drawback of using the TIPS-Tc derivative in devices, however, is that it is prone to a rapid photodegradation under ambient conditions, which calls for investigation of underlying mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Exciton Polariton-Enhanced Photodimerization of Functionalized Tetracene

et al. 2021

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We explore the photodegradation mechanisms in functionalized tetracene (TIPS-Tc) films and how they are influenced by strong exciton−photon coupling in planar microcavities. We demonstrate that degradation of TIPS-Tc films exposed to air proceeds mainly through an oxygen-mediated pathway, assigned to endoperoxide (EPO) formation, whereas degradation in microcavities proceeds through oxygen-independent photodimerization. The aerobic and anaerobic decay mechanisms were found to differ in rate by more than two orders of magnitude. Both the EPO formation and photodimerization proceeded more efficiently in molecules in configurations favorable for the correlated triplet pair (TT) state formation (precursor to the singlet fission) and their immediate surroundings. For the photodimerization, an alkyne dimer is reported as one of the photoproducts, and its optical properties are presented. Strong coupling of TIPS-Tc to resonant microcavities enhanced the photodimerization quantum yield by a factor of 4.2, with the enhancement robust with respect to cavity detuning.

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Section: Discussionmentioning

confidence: 86%

Section: Photodegradation Of Tips-tcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exciton Polariton-Enhanced Photodimerization of Functionalized Tetracene

et al. 2021

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“…This includes materials that have been previously explored for (opto)electronic applications. Examples are photorefractive glasses such as a dicyanomethylenedihydrofuran derivative (exhibiting ultrastrong coupling with Rabi splitting of >1 eV), OLED and OPV materials such as 4,4-cyclohexylidenebis[ N , N -bis(4-methylphenyl)benzenamine] (TAPC) and phthalocyanines, and OFET materials such as derivatives of acenes (e.g., anthracene (Ac), tetracene (Tc), pentacene (Pn)) − and of anthradithiophenes (ADTs) . In addition to their attractive electronic properties, acenes and ADTs have served as model systems for photophysical studies on all levels, from single molecules incorporated in solids, − which began from seminal demonstration of optical detection of single Pn molecules dispersed in a p -terphenyl crystal, to molecular crystals. − Many of these derivatives (including Tc, Pn, and ADT) exhibit singlet fission (SF), the process of creating two triplet (T 1 ) excitons upon excitation of a singlet (S 1 ) state (S 0 + S 1 → TT → T 1 + T 1 , where TT is a correlated triplet pair that serves as a precursor to the free triplets), which has generated a considerable amount of attention due to its potential to enhance the efficiency of organic solar cells …”

Section: Introductionmentioning

confidence: 99%

Exciton Polaritons Reveal “Hidden” Populations in Functionalized Pentacene Films

et al. 2021

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We present a systematic investigation of strong exciton− photon coupling in functionalized pentacene (TIPS-Pn)-based films in allmetal cavities, depending on molecular concentration and film morphology. Rabi splittings of up to 270 meV are observed, with the highest values achieved in pristine amorphous TIPS-Pn films. The exciton−photon interaction strength for the lowest-energy (0−0) excited state scaled with the square root of the molecular density, which was independent of whether the long-range molecular order were present in films. The molecular populations in the disordered regions of the films coupled to the cavity most strongly in all films, including pristine crystalline films. Such populations, with molecular configurations favoring interaction with the cavity electromagnetic field, were not readily identifiable in optical absorption spectra of bare (i.e., not coupled to the cavity) films, which highlights the capability of polariton spectroscopy to reveal these molecular ensembles, which are "hidden" in polycrystalline films. The linear scaling of the exciton−photon interaction strength with the square root of the oscillator strengths was observed in dilute TIPS-Pn:PMMA films but not in pristine TIPS-Pn films, either amorphous or crystalline. In particular, in pristine films, the exciton− photon interaction strength for the vibronic (0−m, m > 0) excitons was higher than expected based on the oscillator strengths extracted from the optical spectra of bare films, which was attributed to enhanced exciton delocalization facilitated by the 2D brickwork motif of TIPS-Pn. Similar observations were made in functionalized anthradithiophene (diF TES-ADT) films (also exhibiting a 2D brickwork packing motif) but not in functionalized tetracene (TIPS-Tc) films, which suggests that the underlying mechanisms rely on short-range intermolecular interactions determined by the molecular packing motif and resulting nanomorphology.

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Molecular packing-dependent exciton dynamics in functionalized anthradithiophene derivatives: From solutions to crystals

Schenck

Mayonado

Anthony

et al. 2020

The Journal of Chemical Physics

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Understanding the impact of inter-molecular orientation on the optical properties of organic semiconductors is important for designing next-generation organic (opto)electronic and photonic devices. However, fundamental aspects of how various features of molecular packing in crystalline systems determine the nature and dynamics of excitons have been a subject of debate. Toward this end, we present a systematic study of how various molecular crystal packing motifs affect the optical properties of a class of high-performance organic semiconductors: functionalized derivatives of fluorinated anthradithiophene. The absorptive and emissive species present in three such derivatives (exhibiting “brickwork,” “twisted-columnar,” and “sandwich-herringbone” motifs, controlled by the side group R) were analyzed both in solution and in single crystals, using various modalities of optical and photoluminescence spectroscopy, revealing the nature of these excited states. In solution, in the emission band, two states were identified: a Franck–Condon state present at all concentrations and an excimer that emerged at higher concentrations. In single crystal systems, together with ab initio calculations, it was found in the absorptive band that Frenkel and Charge Transfer (CT) excitons mixed due to nonvanishing CT integrals in all derivatives, but the amount of admixture and exciton delocalization depended on the packing, with the “sandwich-herringbone” packing motif least conducive to delocalization. Three emissive species in the crystal phase were also identified: Frenkel excitons, entangled triplet pairs 1(TT) (which are precursors to forming free triplet states via singlet fission), and self-trapped excitons (STEs, similar in origin to excimers present in concentrated solution). The “twisted-columnar” packing motif was most conducive to the formation of Frenkel excitons delocalized over 4–7 molecules depending on the temperature. These delocalized Frenkel states were dominant across the full temperature range (78 K–293 K), though at lower temperatures, the entangled triplet states and STEs were present. In the derivative with the “brickwork” packing, all three emissive species were observed across the full temperature range and, most notably, the 1(TT) state was present at room temperature. Finally, the derivative with the “sandwich-herringbone” packing exhibited localized Frenkel excitons and had a strong propensity for self-trapped exciton formation even at higher temperatures. In this derivative, no formation of the 1(TT) state was observed. The temperature-dependent dynamics of these emissive states are reported, as well as their origin in fundamental inter-molecular interactions.

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Strong exciton—photon coupling in anthradithiophene microcavities: from isolated molecules to aggregates

Abstract: Abstract

Cited by 6 publications

References 30 publications

Exciton Polariton-Enhanced Photodimerization of Functionalized Tetracene

Exciton Polariton-Enhanced Photodimerization of Functionalized Tetracene

Exciton Polaritons Reveal “Hidden” Populations in Functionalized Pentacene Films

Molecular packing-dependent exciton dynamics in functionalized anthradithiophene derivatives: From solutions to crystals

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