Factors affecting charge separation and recombination in photoexcited rigid donor-insulator-acceptor compounds

Paddon‐Row, Michael N.; Oliver, Anna M.; Warman, John M.; Smit, Kenneth J.; Haas, Matthijs P. de; Oevering, Henk; Verhoeven, J. W.

doi:10.1021/j100335a024

Cited by 123 publications

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“…The highest ratio between electron transfer after local D or A excitation and thermal decay of the CT state achieved in rigid dyads was, until recently, on the order of a 1000-fold. [20,21] Several approaches have been proposed to improve this situation. A very elegant approach, initially envisaged by Zimmt et al [22,23] and later investigated by others, [24] rests on the idea of designing dyads in which the electronic coupling V* involved in photoinduced electron transfer from a locally excited state to the CT state is much larger than that involved in decay of the CT state to the ground state (V).…”

Section: Overview Of Approaches To Realizing a Long-lived Ct State Inmentioning

confidence: 99%

Long‐Lived Charge‐Transfer States in Compact Donor–Acceptor Dyads

et al. 2005

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Photoinduced electron transfer is a widely applied method to convert photon energy into a useful (electro)chemical potential, both in nature and in artificial devices. There is a continuing effort to develop molecular systems in which the charge-transfer state, populated by photoinduced electron transfer, survives sufficiently long to tap the energy stored in it. In general this has been found to require the construction of rather complex molecular systems, but more recently a few approaches have been reported that allow the use of much more simple and relatively small electron donor-acceptor dyads for this purpose. The most successful examples of such systems seem to be those that apply "electron spin control" to slow down the spontaneous decay of the charge-transfer state, and these are reviewed in this minireview, with a discussion of the underlying principles and a critical evaluation of some of the claims made with regard to using a pronounced "inverted-region effect" as an alternative method to prolong the lifetime of charge-transfer states.

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Section: Overview Of Approaches To Realizing a Long-lived Ct State Inmentioning

confidence: 99%

Long‐Lived Charge‐Transfer States in Compact Donor–Acceptor Dyads

et al. 2005

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“…Similar ring structures have been used earlier to slow down electron transfer in donor-bridge-acceptor molecules. 16,17 The electronic interaction at the interface can be enhanced if a shorter bond is formed between the chromophore and the semiconductor than is realized by the -COOH anchor group. For example, the chromophore catechol binds directly via its two oxygen atoms to one or two Ti atoms on the TiO 2 surface.…”

Section: Introductionmentioning

confidence: 99%

Test of theoretical models for ultrafast heterogeneous electron transfer with femtosecond two-photon photoemission data

2009

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Abstract. The energy distribution of electrons injected into acceptor states on the surface of TiO 2 was measured with femtosecond two-photon photoemission. Shape and relative energetic position of these distribution curves with respect to the corresponding donor states, i.e. of perylene chromophores in the first excited singlet state attached via different bridge-anchor groups to the TiO 2 surface, were compared with the predictions of different theoretical models for light-induced ultrafast heterogeneous electron transfer (HET). Gerischer's early scenario for light-induced HET was considered and two recent explicit calculations, i.e. a fully quantum mechanical analytical model and a time-dependent density functional theory model based on molecular dynamics simulations for the vibrational modes were also considered. Based on the known vibrational structure in the photoionization spectrum of perylene in the gas phase and that measured in the linear absorption spectra of the perylene chromophores anchored on the TiO 2 surface the energy distribution curves for the injected electrons were fitted assuming the excitation of the dominant 0⋅17 eV vibrational mode in the ionized perylene chromophore leading to a corresponding Franck-Condon dictated progression in the energy distribution curves. Each individual peak was fitted with a Voigt profile where the Lorentzian contribution was taken from the time-resolved HET data and the Gaussian contribution attributed to inhomogeneous broadening. The measured room temperature energy distribution curves for the injected electrons are explained with the fully quantum mechanical model for light-induced HET with the high energy, 0⋅17 eV, skeletal stretching mode excited in the ionized perylene chromophore. The corresponding energy distribution of the injected electrons is fully accommodated in acceptor states on the TiO 2 surface fulfilling the wide band limit.

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“…[4] This work is especially pertinent to the present study because it also employed naphthalene derivatives and nitriles as the redox active species. In particular, the lifetime of the charge-separated state of their bridged system, where the dimethoxynaphthalene cation is separated by four sigma bonds (4.6 [5] ) from the dicyanoethylene anion, remained constant at 8 ns, even when the temperature was lowered to À23 8C. Another influential study was carried out by Miyasaka et al [6] who showed that charge recombinations in porous glass follow the same free-energy relationships as those observed in polar solvents and that these relationships are maintained at À196 8C (77 K).…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Ultra‐Exothermic Charge Recombinations

et al. 2006

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We measured the temperature dependence (from +32 to −50 °C) of charge‐recombination rates between contact radical ion pairs in isopropyl ether. In the systems selected for this study, aromatic hydrocarbon cations are the electron acceptors and the fumaronitrile anion is the electron donor. Nearly quantitative electron transfers occur at all temperatures. The charge recombinations have excess exothermicities of −60 kcal mol−1 and exhibit a very weak temperature dependence. Our observations emphasize the absence of solvent effects and the relevance of nuclear tunneling in charge recombinations.

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Factors affecting charge separation and recombination in photoexcited rigid donor-insulator-acceptor compounds

Cited by 123 publications

References 0 publications

Long‐Lived Charge‐Transfer States in Compact Donor–Acceptor Dyads

Long‐Lived Charge‐Transfer States in Compact Donor–Acceptor Dyads

Test of theoretical models for ultrafast heterogeneous electron transfer with femtosecond two-photon photoemission data

Temperature Dependence of Ultra‐Exothermic Charge Recombinations

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