Triplet Excitons of Carotenoids Formed by Singlet Fission in a Membrane

Wang, Chen; Schlamadinger, Diana E.; Desai, Varsha G.; Tauber, Michael J.

doi:10.1002/cphc.201100571

Cited by 61 publications

(67 citation statements)

References 43 publications

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“…Yet, some J-aggregates may have S 1 lifetimes close to those reported for monomers [11,12]. Moreover, aggregation facilitates ultrafast formation of a triplet state, most likely via singlet fission [10,13] that may prove important for the future design of devices aiming for conversion of solar energy [15].…”

Section: Introductionmentioning

confidence: 85%

“…Time-resolved data for carotenoid aggregates are so far available only for zeaxanthin whose aggregates were studied by means of femtosecond transient absorption [11,12] and picosecond Raman spectroscopy [10,13], and synthetic 8 0 -apo-b-carotenal [14]. For both carotenoids, significant aggregation-induced changes in excited-state dynamics were reported.…”

Section: Introductionmentioning

confidence: 99%

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Excited-state dynamics of astaxanthin aggregates

Fuciman

Durchan

Šlouf

et al. 2013

Chemical Physics Letters

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Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Excited-state dynamics of astaxanthin aggregates

Fuciman

Durchan

Šlouf

et al. 2013

Chemical Physics Letters

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“…18 Among the important questions that remain from the work on photosynthetic systems is the identity of the chromophores involved in the singlet fission process. [15][16][17]19,20 More generally, researchers have endeavored to understand the factors that influence singlet fission in these and numerous other conjugated molecules. 13 Recent efforts have centered on the energy levels of the constituent chromophores, 21 the effect of the number of chromophores involved, 22,23 and the strength and orientation of the intermolecular electronic coupling.…”

Section: Introductionmentioning

confidence: 99%

“…13,22,24 We have investigated singlet fission within assemblies of the carotenoid zeaxanthin. 19,25 These studies utilized picosecond-to-nanosecond time-resolved resonance Raman spectroscopy (ps-TRRR). A high yield of triplet excited states, formed via intermolecular singlet fission, was found in a weakly-coupled aggregate.…”

Section: Introductionmentioning

confidence: 99%

Singlet fission in carotenoid aggregates: insights from transient absorption spectroscopy

et al. 2012

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The excited-state dynamics of three types of zeaxanthin aggregates are probed with transient absorption spectroscopy on the femtosecond-to-microsecond timescale. Triplet excited states form via singlet fission in all three aggregates within several hundred femtoseconds. The transient absorption spectra are consistent with an S 2 , but not S 1 , parent state for singlet fission. The quantum yield of triplet states in one of the weakly-coupled aggregates is at least 60-80% immediately following photoexcitation. The same aggregate has a 10-30% yield of S 1 excited states, which have a dominant decay time of ~8 ps. For the strongly-coupled H-aggregate, a new transient absorption band with maximum 400−420 nm is found. The band is assigned to a triplet state with T 1 →T n transition that is strongly exciton-coupled to either the S 0 →S 2 transition of surrounding ground-state chromophores, or a T 1 →T n transition of a nearby triplet excited state. The yield of triplet states could be 180% or more in the stronglycoupled aggregate, as inferred from the absence of S 1 signal. Fast annihilation depletes most of the triplet population in the aggregates on the picosecond timescale, however a measurable fraction persists beyond 1 µs.

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“…24−30 Because of its role in a variety of biological systems, 24,25,31,32 as well as its use in molecular structures used to study energy-and charge-transfer for artificial photosynthesis, 20,27,33−35 the excited-state behavior of β-carotene has been extensively characterized, 36 most notably with time-resolved absorption 9,20,26,37−40 and Raman spectroscopies. [28][29][30]41 Its molar absorptivity is extremely high (on the order of 10 5 M −1 cm −1 in most solvents) for both the symmetry-allowed ground-state S 2 ← S 0 transition and the T n ← T 1 transient absorption. 20,26 Carotenoids have long been known to undergo SF in photosynthetic bacteria, 32,25 as first studied in spirilloxanthin and rhodopsin by picosecond transient absorption spectroscopy 42 and picosecond resonance Raman spectroscopy, 43 with an intramolecular homofission mechanism later elaborated.…”

Section: ■ Introductionmentioning

confidence: 99%

Fast Triplet Formation via Singlet Exciton Fission in a Covalent Perylenediimide-β-apocarotene Dyad Aggregate

et al. 2015

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A covalent dyad was synthesized in which perylene-3,4,:9:10-bis(dicarboximide) (PDI) is linked to β-apocarotene (Car) using a biphenyl spacer. The dyad is monomeric in toluene and forms a solution aggregate in methylcyclohexane (MCH). Using femtosecond transient absorption (fsTA) spectroscopy, the monomeric dyad and its aggregates were studied both in solution and in thin films. In toluene, photoexcitation at 530 nm preferentially excites PDI, and the dyad undergoes charge separation in τ = 1.7 ps and recombination in τ = 1.6 ns. In MCH and in thin solid films, 530 nm excitation of the PDI-Car aggregate also results in charge transfer that competes with energy transfer from (1)*PDI to Car and with an additional process, rapid Car triplet formation in <50 ps. Car triplet formation is only observed in the aggregated PDI-Car dyad and is attributed to singlet exciton fission (SF) within the aggregated PDI, followed by rapid triplet energy transfer from (3)*PDI to the carotenoid. SF from β-apocarotene aggregation is ruled out by direct excitation of Car films at 414 nm, where no triplet formation is observed. Time-resolved electron paramagnetic resonance measurements on aggregated PDI-Car show the formation of (3)*Car with a spin-polarization pattern that rules out radical-pair intersystem crossing as the mechanism of triplet formation as well.

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Triplet Excitons of Carotenoids Formed by Singlet Fission in a Membrane

Cited by 61 publications

References 43 publications

Excited-state dynamics of astaxanthin aggregates

Excited-state dynamics of astaxanthin aggregates

Singlet fission in carotenoid aggregates: insights from transient absorption spectroscopy

Fast Triplet Formation via Singlet Exciton Fission in a Covalent Perylenediimide-β-apocarotene Dyad Aggregate

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