Long-Lived Short-Distance Intramolecular Charge Separation via Intermolecular Triplet Sensitisation

Hviid, Lene; Brouwer, Albert M.; Paddon‐Row, Michael N.; Verhoeven, J. W.

doi:10.1002/1439-7641(20010417)2:4<232::aid-cphc232>3.3.co;2-v

Cited by 20 publications

(28 citation statements)

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“…Subsequent electron transfer is fast, and results in a triplet CT state with a lifetime in the microsecond range, as we reported in a preliminary Communication (see ref. 32). In this contribution, we will give full experimental details and describe the effects of solvent polarity.…”

Section: Introductionmentioning

confidence: 99%

Spin control of the lifetime of an intramolecular charge-transfer excited state

Hviid

Bouwman

Paddon‐Row

et al. 2003

Photochem Photobiol Sci

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Triplet-sensitized generation of a long-lived intramolecular charge-separated excited state is described in an electron donor-acceptor molecule with a short distance between the donor and the acceptor. Time-resolved UV-Vis optical absorption spectroscopy shows that the lifetime of this triplet excited state is 1.4 micros in acetonitrile at 298 K, i.e. five orders of magnitude greater than that of the corresponding singlet charge-separated state. In slightly less polar alkane nitrile solvents, the local and CT triplet states coexist, which allows determination of their relative energies.

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Section: Introductionmentioning

confidence: 99%

Spin control of the lifetime of an intramolecular charge-transfer excited state

Hviid

Bouwman

Paddon‐Row

et al. 2003

Photochem Photobiol Sci

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“…15 Therefore, it was necessary to stop the reaction when the reaction was incomplete to avoid formation of undesired byproducts resulting from multiple addition to C 60 . The model and triad complexes, Pt 2 Th and Pt 2 ThC 60 were fully characterized by 1 H, 13 C, 31 P NMR spectroscopy and mass spectrometry and the spectral data are provided as supporting information.w The spectral data are consistent with the structures, with one interesting feature. Specifically, the 31 P NMR spectrum of Pt 2 PtC 60 is split into a closely spaced doublet.…”

Section: Synthesismentioning

confidence: 80%

“…Specifically, in bimolecular systems the efficiency for cage-escape of the geminate ion-pair produced by photoinduced charge transfer is enhanced significantly when the excited state is a spin-triplet. [29][30][31][32][33][34] In donor-acceptor dyad systems the lifetime of the charge separated state is lengthened substantially when the excited state is a spin-triplet state compared to structurally analogous dyads in which a singlet excited state precedes charge separation. [31][32][33][34] Recently, several groups, including our own, have initiated studies that have the objective of harnessing the triplet state to enhance the efficiency of photoinduced charge separation in OPVs.…”

Section: Introductionmentioning

confidence: 99%

“…[29][30][31][32][33][34] In donor-acceptor dyad systems the lifetime of the charge separated state is lengthened substantially when the excited state is a spin-triplet state compared to structurally analogous dyads in which a singlet excited state precedes charge separation. [31][32][33][34] Recently, several groups, including our own, have initiated studies that have the objective of harnessing the triplet state to enhance the efficiency of photoinduced charge separation in OPVs. In one report, Yang and co-workers reported fabrication of OPVs based on platinum(II) octaethylporphyrin and C 60 which operate with an overall power conversion efficiency of 41%.…”

Section: Introductionmentioning

confidence: 99%

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A fulleropyrrolidine end-capped platinum-acetylide triad: the mechanism of photoinduced charge transfer in organometallic photovoltaic cells

Guo

Ogawa

Kim

et al. 2007

Phys. Chem. Chem. Phys.

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The fullerene end-capped platinum acetylide donor-acceptor triad Pt(2)ThC(60) was synthesized and characterized by using photophysical methods and photovoltaic device testing. The triad consists of the platinum acetylide oligomer Ph-[triple bond, length as m-dash]-Pt(PBu3)2-[triple bond, length as m-dash]-Th-[triple bond, length as m-dash]-Pt(PBu3)2-[triple bond, length as m-dash]-Ph (Ph=phenyl and Th=2,5-thienyl, stereochemistry at both Pt centers is trans) that contains fulleropyrrolidine moieties on each of the terminal phenylene units. Electrochemistry of the triad reveals relatively low potential oxidation and reduction waves corresponding, respectively, to oxidation of the platinum acetylide and reduction of the fulleropyrrolidine units. Photoluminescence spectroscopy shows that the singlet and triplet states of the platinum acetylide chromophore are strongly quenched in the triad assembly, both in solution at ambient temperature as well as in a low-temperature solvent glass. The excited state quenching arises due to intramolecular photoinduced electron transfer to produce a charge separated state based on charge transfer from the platinum acetylide (donor) to the fulleropyrrolidine (acceptor). Picosecond time resolved absorption spectroscopy confirms that the charge transfer state is produced within 1 ps of photoexcitation, and it decays by charge recombination within 400 ps. Organic photovoltaic devices fabricated using spin-coated films of Pt2ThC60 as the active material operate with modest efficiency, exhibiting a short circuit photocurrent of 0.51 mA cm(-2) and an open circuit voltage of 0.41 V under 100 mW cm(-2)/AM1.5 illumination. The results are discussed in terms of the relationship between the mechanism of photoinduced electron transfer in the triad and the comparatively efficient photovoltaic response exhibited by the material.

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“…16,17 There are now several examples of this latter behaviour. [18][19][20][21][22] Despite these apparent difficulties, there have been two recent reports 23,24 describing unusually long-lived photoredox states for rather simple molecular dyads.…”

Section: Introductionmentioning

confidence: 99%

The effect of solvent polarity on the photophysical properties of 4-cyano-(4′-methylthio)diphenylacetylene: A prototypic donor–acceptor system

Benniston

Harriman

Rostron

2005

Phys. Chem. Chem. Phys.

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The photophysical properties of the target compound are extremely sensitive to changes in solvent polarity since the lowest-energy excited states possess considerable charge-transfer character. Excitation results in a greatly increased dipole moment, with the resultant excited singlet state retaining a lifetime of ca. 1 ns in all solvents. Radiative decay involves coupling between the lowest-energy excited singlet state and both the ground state and an upper excited singlet state. The level of coupling to the upper singlet decreases in non-polar solvents, presumably due to symmetry factors. The radiative rate constant decreases smoothly with increasing solvent polarity function as the molecule acquires an ever increasing dipolar character. Non-radiative decay includes both intersystem crossing and internal conversion, but the former process dominates in polar solvents. The excited singlet state lifetime is very weakly dependent upon temperature in the solid state. However, in polar solutions where the Stokes' shift decreases with decreasing temperature, there is clear evidence for an activated process. This is believed to involve coupling to the upper-lying singlet excited state.

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Long-Lived Short-Distance Intramolecular Charge Separation via Intermolecular Triplet Sensitisation

Cited by 20 publications

References 0 publications

Spin control of the lifetime of an intramolecular charge-transfer excited state

Spin control of the lifetime of an intramolecular charge-transfer excited state

A fulleropyrrolidine end-capped platinum-acetylide triad: the mechanism of photoinduced charge transfer in organometallic photovoltaic cells

The effect of solvent polarity on the photophysical properties of 4-cyano-(4′-methylthio)diphenylacetylene: A prototypic donor–acceptor system

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