Determination of the electronic density of states at a nanostructured TiO2/Ru-dye/electrolyte interface by means of photoelectron spectroscopy

Westermark, Karin; Henningsson, Anders; Rensmo, Håkan; Södergren, Sven; Siegbahn, Hans; Hagfeldt, Anders

doi:10.1016/s0301-0104(02)00699-7

Cited by 61 publications

(61 citation statements)

References 38 publications

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“…In the spectra of the clean TiO 2 surface, we observe the valence band edge at an energy of about 3 eV versus the Fermi level as expected for a clean rutile TiO 2 ͑110͒. 54 The spectra of the clean TiO 2 only reveal a minor amount of states in the bandgap region centered at about 1.0 eV as expected for a clean well ordered crystalline surface.…”

Section: Molecular Valence Electronic Structuresupporting

confidence: 67%

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Johansson

Odelius

Karlsson

et al. 2008

The Journal of Chemical Physics

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The molecular and electronic surface structure of a triarylamine based hole-conductor (HC) molecule evaporated onto rutile TiO2(110) single crystal is investigated by means of synchrotron light based photoelectron spectroscopy and x-ray absorption spectroscopy in combination with calculations based on density functional theory. Different amounts of the HC molecule was evaporated spanning the monolayer to multilayer region. The molecular surface structure is investigated and the results indicate that no specific covalent chemical bonding is formed and that the plane formed by the different nitrogens in the HC molecules has a rather small angle versus the TiO2 substrate surface plane. Some molecular ordering also persists in the multilayer region. The experimental core level spectra, valence level spectra, and the N 1s x-ray absorption spectroscopy spectra are well modeled by calculations on an individual molecule. Interestingly, the formation of the TiO2HC interface results in significant binding energy shifts in core levels and valence levels shifting all peaks of a the HC material to the same extent. Smaller shifts were also observed in the substrate core level peaks. The shift is discussed in terms of nanoscale energy level bending and final state hole screening. With respect to electronic applications, specifically in a solid state dye-sensitized solar cell, it is argued that the observed energy level alignment at the TiO2HC interface can act as a hole trap.

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Section: Molecular Valence Electronic Structuresupporting

confidence: 67%

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Johansson

Odelius

Karlsson

et al. 2008

The Journal of Chemical Physics

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“…The conduction band position is indicated at the Fermi level of the blank titanium dioxide surface here, as this level can be seen as an upper binding energy limit for the conduction band position. 29 Indicating the relaxed excited state at the position of the 10 % absorption onset one notices that it is located below the TiO 2 conduction band for all dyes. We observed this previously for ID176 and suggested that band gap states might be relevant for electron injection.…”

Section: Id28mentioning

confidence: 94%

Energy alignment and surface dipoles of rylenedyes adsorbed to TiO2nanoparticles

Cappel

Plogmaker

Johansson

et al. 2011

Phys. Chem. Chem. Phys.

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The energy loss in dye-sensitized solar cells calculated from the energy difference between the lowest electronic transition of the dye and the obtained open-circuit voltage is often 1 eV or even more. To minimize this loss, it is important to accurately determine the energy alignment at the TiO 2 /dye/redox-mediator interface. In this study, we compared the results from electrochemistry and photoelectron spectroscopy for determining the energy alignment of three rylene dyes, two of which absorb relatively far in the red. The trends observed with the methods were different, as in the former, the energy alignment is measured relative to an external reference and includes contributions from solvent reorganization energies, while in the latter, it is measured relative to the energetics of the TiO 2 and is lacking such contributions. The influence of the dyes' dipole moments on the energetics of the TiO 2 was also measured and explained some of the differences in trends. Finally, we compared the injection efficiencies of the two red-absorbing dyes and found that the differences in injection efficiencies can be better explained using the energy alignment determined from photoelectron spectroscopy. This shows that the method for measuring the energetics of a DSC should be chosen according to what process one intends to study.

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“…Therefore, it is questionable whether it is possible to combine spectra obtained by means of PES and absorption spectroscopies, as it was carried out in Ref. 42 In that work, the absorption spectrum was shifted on the energy scale to match the difference between the absorption and emission peak positions with the photon energy.…”

Section: Ultrafast Kinetics On Dye-sensitized Samplesmentioning

confidence: 99%

Injection Kinetics and Electronic Structure at the N719/TiO₂ Interface Studied by Means of Ultrafast XUV Photoemission Spectroscopy

Borgwardt

Wilke

Kampen³

et al. 2015

J. Phys. Chem. C

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The method of transient XUV photoemission spectroscopy is developed to investigate the ultrafast dynamics of heterogeneous electron transfer at the interface between the N719 ruthenium dye complex and TiO 2 nanoparticles. XUV light from highorder harmonic generation is used to probe the electron density distribution among the ground and excited states at the interface after its exposure to a pump laser pulse

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Determination of the electronic density of states at a nanostructured TiO2/Ru-dye/electrolyte interface by means of photoelectron spectroscopy

Cited by 61 publications

References 38 publications

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Energy alignment and surface dipoles of rylenedyes adsorbed to TiO2nanoparticles

Injection Kinetics and Electronic Structure at the N719/TiO₂ Interface Studied by Means of Ultrafast XUV Photoemission Spectroscopy

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Determination of the electronic density of states at a nanostructured TiO2/Ru-dye/electrolyte interface by means of photoelectron spectroscopy

Cited by 61 publications

References 38 publications

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Interface electronic states and molecular structure of a triarylamine based hole conductor on rutile TiO2(110)

Energy alignment and surface dipoles of rylenedyes adsorbed to TiO2nanoparticles

Injection Kinetics and Electronic Structure at the N719/TiO2 Interface Studied by Means of Ultrafast XUV Photoemission Spectroscopy

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Injection Kinetics and Electronic Structure at the N719/TiO₂ Interface Studied by Means of Ultrafast XUV Photoemission Spectroscopy