Distance dependence of heterogeneous electron transfer probed in ultra-high vacuum with femtosecond transient absorption

Ernstorfer, Ralph; Felber, Silke; Storck, W.; Galoppini, Elena; Wei, Qinhua; Willig, F.

doi:10.1163/1568567054908970

Cited by 17 publications

(15 citation statements)

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“…This trend is not surprising given that the amount of adsorbed RuP and the light-harvesting efficiency decrease with each B n layer. Additionally, it has previously been shown using insulating metal oxide layers, − covalent bridges, − and variations in the length of the bridge in metal ion-linked multilayers , that the excited state electron injection rate ( k inj in Figure ) and efficiency decrease with increasing spatial separation between the dye and TiO 2 , resulting in a lower J sc .…”

Section: Results and Discussionmentioning

confidence: 99%

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

Robb

Miles

Salpage

et al. 2020

ACS Appl. Mater. Interfaces

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Metal ion-linked multilayers offer an easily prepared and modular architecture for controlling energy and electron transfer events on nanoparticle, metal oxide films. However, unlike with planar electrodes, the mesoporous nature of the films inherently limits both the thickness of the multilayer and subsequent diffusion through the pores. Here, we systematically investigated the role of TiO 2 nanoparticle film porosity and metal ion-linked multilayer thickness in surface loading, through-pore diffusion, and overall device performance. The TiO 2 porosity was controlled by varying TiO 2 sintering times. Molecular multilayer thickness was controlled through assembling Zn II -linked bridging molecules (B = p-terphenyl diphosphonic acid) between the metal oxide and the Ru(bpy) 2 ((4,4′-PO 3 H 2 ) 2 bpy)]Cl 2 dye (RuP), thus producing TiO 2 -(B n )-RuP films. Using attenuated total reflectance infrared absorption and UV−vis spectroscopy, we observed that at least two molecular layers (i.e., TiO 2 -B 2 or TiO 2 -B 1 -RuP) could be formed on all films but subsequent loading was dependent on the porosity of the TiO 2 . Rough estimates indicate that in a film with 34 nm average pore diameter, the maximum multilayer film thickness is on the order of 4.6−6 nm, which decreases with decreasing pore size. These films were then incorporated as the photoanodes in dye-sensitized solar cells with cobalt(II/III)tris(4,4′-di-tert-butyl-2,2′-bipyridine) as a redox mediator. In agreement with the surface-loading studies, electrochemical impedance spectroscopy measurements indicate that mediator diffusion is significantly hindered in films with thicker multilayers and less porous TiO 2 . Collectively, these results show that care must be taken to balance multilayer thickness, substrate porosity, and size of the mediator in designing and maximizing the performance of new multilayer energy and electron management architectures.

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Section: Results and Discussionmentioning

confidence: 99%

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

Robb

Miles

Salpage

et al. 2020

ACS Appl. Mater. Interfaces

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“…27 Furthermore, electron transfer to a semiconductor was observed also for dyes (both organic and organometallic) whose main chromophore was separated from the anchoring group by a saturated carbon chain, albeit at a reduced rate compared to the fully conjugated compounds. 28…”

Section: Resultsmentioning

confidence: 99%

New Blue Donor–Acceptor Pechmann Dyes: Synthesis, Spectroscopic, Electrochemical, and Computational Studies

et al. 2019

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The design, synthesis, and characterization of a new class of blue-colored thiophene-substituted Pechmann dyes are reported. Due to a distinguishing blue coloration and the capability to absorb light in one of the most photon-dense regions of the solar spectrum, such compounds are of great interest for application as photoactive materials in organic optoelectronics, in particular, in dye-sensitized solar cells. To achieve fine tuning of the optical and electrochemical properties, the electron-poor thiophene-bis-lactone moiety has been decorated with donor (D) and acceptor groups (A), targeting fully conjugated D–A−π–A structures. The designed structures have been investigated by means of DFT and time-dependent DFT calculations, and the most promising dyes have been synthesized. These molecules represent the very first preparation of unsymmetrical Pechmann derivatives. Optical and electrochemical properties of the new dyes have been studied by cyclic voltammetry and UV–vis and fluorescence spectroscopy. In two cases, test cells were built proving that a photocurrent can indeed be generated when using electrolytes especially formulated for narrow-band-gap dyes, although with a very low efficiency.

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“…It is accepted that the electron transfer is highly sensitive to the distance between donor and acceptor. Studies had indicated that β has a greater value for through-space coupling compared to through-bond coupling. , However, the quantitative estimation of β value related to a true electron-transfer distance and hence the electronic coupling between the excited state of the sensitizer and acceptor orbitals at the surface of TiO 2 is challenging because of the complexity, inherent heterogeneity, and the involvement of different factors affecting the electronic coupling at the interface. A small distance between ZnTMPyP and TiO 2 NP surface would enhance the electron injection efficiency to TiO 2 .…”

Section: Resultsmentioning

confidence: 99%

Electronic Coupling–Decoupling-Dependent Single-Molecule Interfacial Electron Transfer Dynamics in Electrostatically Attached Porphyrin on TiO₂ Nanoparticles

Dhital

Rao

2016

J. Phys. Chem. C

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Distance dependence of heterogeneous electron transfer probed in ultra-high vacuum with femtosecond transient absorption

Cited by 17 publications

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Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

New Blue Donor–Acceptor Pechmann Dyes: Synthesis, Spectroscopic, Electrochemical, and Computational Studies

Electronic Coupling–Decoupling-Dependent Single-Molecule Interfacial Electron Transfer Dynamics in Electrostatically Attached Porphyrin on TiO₂ Nanoparticles

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Distance dependence of heterogeneous electron transfer probed in ultra-high vacuum with femtosecond transient absorption

Cited by 17 publications

References 0 publications

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

New Blue Donor–Acceptor Pechmann Dyes: Synthesis, Spectroscopic, Electrochemical, and Computational Studies

Electronic Coupling–Decoupling-Dependent Single-Molecule Interfacial Electron Transfer Dynamics in Electrostatically Attached Porphyrin on TiO2 Nanoparticles

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Electronic Coupling–Decoupling-Dependent Single-Molecule Interfacial Electron Transfer Dynamics in Electrostatically Attached Porphyrin on TiO₂ Nanoparticles