Ultrafast Electron Transfer Dynamics of a Zn(II)porphyrin−Viologen Complex Revisited: S<sub>2</sub> vs S<sub>1</sub> Reactions and Survival of Excess Excitation Energy

Petersson, Jonas; Eklund, Mattias; Davidsson, Jan; Hammarström, Leif

doi:10.1021/jp911686z

Cited by 63 publications

(93 citation statements)

References 58 publications

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“…A detailed description is refer to Petersson et al 41. Briefly, the output from a Coherent Legend Ti:Sapphire amplifier (1 kHz, λ =800 nm, FWHM (full-width at half-maximum) 100 fs) was split into a pump and a probe part.…”

Section: Methodsmentioning

confidence: 99%

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

et al. 2016

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Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy—by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte—to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system.

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Section: Methodsmentioning

confidence: 99%

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

et al. 2016

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“…For a detailed description, see Petersson et al 33 Briefly, the output from a Coherent Legend Ti:Sapphire amplifier (1 kHz, λ = 800 nm, fwhm 100 fs) was split into a pump and a probe part. For a detailed description, see Petersson et al 33 Briefly, the output from a Coherent Legend Ti:Sapphire amplifier (1 kHz, λ = 800 nm, fwhm 100 fs) was split into a pump and a probe part.…”

Section: Ultrafast Femtosecond Transient Absorption Spectrometermentioning

confidence: 99%

Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells

Zhang

Favereau

Farré

et al. 2016

Phys. Chem. Chem. Phys.

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In a photophysical study, two diketopyrrolopyrrole (DPP)-based sensitizers functionalized with 4-thiophenecarboxylic acid as an anchoring group and a bromo (DPPBr) or dicyanovinyl (DPPCN2) group, and a dyad consisting of a DPP unit linked to a naphthalenediimide group (DPP-NDI), were investigated both in solution and grafted on mesoporous NiO films. Femtosecond transient absorption measurements indicate that ultrafast hole injection occurred predominantly on a timescale of ∼200 fs, whereas the subsequent charge recombination occurred on a surprisingly wide range of timescales, from tens of ps to tens of μs; this kinetic heterogeneity is much greater than is typically observed for dye-sensitized TiO2 or ZnO. Also, in contrast to what is typically observed for dye-sensitized TiO2, there was no significant dependence on the excitation power of the recombination kinetics, which can be explained by the hole density being comparatively higher near the valence band of NiO before excitation. The additional acceptor group in DPP-NDI provided a rapid electron shift and stabilized charge separation up to the μs timescale. This enabled efficient (∼95%) regeneration of NDI by a Co(III)(dtb)3 electrolyte (dtb = 4,4'-di-tert-butyl-2,2'-bipyridine), according to transient absorption measurements. The regeneration of DPPBr and DPPCN2 by Co(III)(dtb)3 was instead inefficient, as most recombination for these dyes occurred on the sub-ns timescale. The transient spectroscopy data thus corroborated the trend of the published photovoltaic properties of dye-sensitized solar cells (DSSCs) based on these dyes on mesoporous NiO, and show the potential of a design strategy with a secondary acceptor bound to the dye. The study identifies rapid initial recombination between the dye and NiO as the main obstacle to obtaining high efficiencies in NiO-based DSSCs; these recombination components may be overlooked when studies are conducted using only methods with ns resolution or slower.

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“…42 For F 10 C, the comparison of different TA spectra at several given time points are shown in the right panel of Fig. 3.…”

Section: Vibrational Relaxationmentioning

confidence: 99%

Photophysical properties of electron-deficient free-base corroles bearing meso-fluorophenyl substituents

Zhang

Liu

Zhan

et al. 2015

Photochem Photobiol Sci

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The ultrafast photophysical behaviors of a series of meso-fluorophenyl substituted electron-deficient free base corroles F0C, F5C, F10C and F15C in toluene have been investigated using femtosecond time resolved absorption spectroscopy and steady-state spectroscopy. The S2→S1* transformation was found to be accelerated with the enhancement of electron-deficiency (from 550 fs for F0C to 140 fs for F15C), while S1*→S1 prolonged from ∼9 ps for F0C to ∼24 ps for F15C, which was assigned to an intermolecular vibrational cooling process. The intersystem crossing process was directly observed. The intersystem crossing rate constant (kISC) from S1 to T1 was found to increase significantly with the fluorophenyl substituents (from F0C to F10C), while it does not totally follow the trend of the increase of the atomic number of the peripheral fluorine atoms. The order of ISC time constants from larger to smaller is F0C < F5C < F10C > F15C. It indicates that the electron-withdrawing effect of fluorophenyl substitutions, together with the heavy atom effect, influences the photophysical properties of excited states of corroles.

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Ultrafast Electron Transfer Dynamics of a Zn(II)porphyrin−Viologen Complex Revisited: S₂ vs S₁ Reactions and Survival of Excess Excitation Energy

Cited by 63 publications

References 58 publications

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells

Photophysical properties of electron-deficient free-base corroles bearing meso-fluorophenyl substituents

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Ultrafast Electron Transfer Dynamics of a Zn(II)porphyrin−Viologen Complex Revisited: S2 vs S1 Reactions and Survival of Excess Excitation Energy

Cited by 63 publications

References 58 publications

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

Ultrafast and slow charge recombination dynamics of diketopyrrolopyrrole–NiO dye sensitized solar cells

Photophysical properties of electron-deficient free-base corroles bearing meso-fluorophenyl substituents

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Ultrafast Electron Transfer Dynamics of a Zn(II)porphyrin−Viologen Complex Revisited: S₂ vs S₁ Reactions and Survival of Excess Excitation Energy