Femtosecond Electron Transfer from the Excited State of Chemically Anchored Chromophores into the Empty Conduction Band of Nanocrystalline Spong-like TiO<sub>2</sub> Films*

Burfeindt, Bernd; Zimmermann, C.; Ramakrishna, S.; Hannappel, Thomas; Meissner, Britta; Storck, W.; Willig, F.

doi:10.1524/zpch.1999.212.part_1.067

Cited by 22 publications

(5 citation statements)

References 17 publications

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“…Work with perylene sensitizers for nanocrystalline substrates has shown that the electron transfer to the solid occurs before thermal equilibration of the excited state . Therefore, the ability of the excited sensitizer can no longer be described by E o D+/D* , but rather by the total energetic overlap of the spectral distribution function of the excited state with the acceptor states of the TiO 2 conduction band.…”

Section: Discussionmentioning

confidence: 99%

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

2001

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New chromophores were explored for use in dye-sensitized solar cells. The attachment of various di-carboxylated cyanine dyes to nanocrystalline TiO2 was examined spectroscopically and through their performance in a sensitized solar cell. It was found that aggregated forms of these cyanine dyes sensitized with an efficiency equal to that of the monomer form and that combinations of cyanine dyes could be used to sensitize solar cells over the entire visible spectrum. With the high extinction coefficients of the organic dyes, short circuit photocurrents for these cyanine-sensitized systems was maximized at a 4 μm thickness of the nanocrystalline TiO2. Short circuit photocurrents for these 4 μm solar cells were found to exceed that of ruthenium coordination complexes.

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Section: Discussionmentioning

confidence: 99%

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

2001

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“…Generation of a photocurrent in the DSC occurs when light is absorbed by the sensitizer dye, resulting in ultra-fast electron injection into the conduction band of the TiO 2 . [28][29][30][31] The injected electrons move through the network of interconnected oxide particles (typical size 30-40 nm) by a random walk process 32 until they reach the conducting glass substratez. The oxidized dye is regenerated by rapid electron transfer from the iodide ions in the electrolyte before it has time to undergo irreversible bleaching.…”

Section: Introductionmentioning

confidence: 99%

Dye-sensitized nanocrystalline solar cells

Peter

2007

Phys. Chem. Chem. Phys.

359

269

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The basic physical and chemical principles behind the dye-sensitized nanocrystalline solar cell (DSC: also known as the Grätzel cell after its inventor) are outlined in order to clarify the differences and similarities between the DSC and conventional semiconductor solar cells. The roles of the components of the DSC (wide bandgap oxide, sensitizer dye, redox electrolyte or hole conductor, counter electrode) are examined in order to show how they influence the performance of the system. The routes that can lead to loss of DSC performance are analyzed within a quantitative framework that considers electron transport and interfacial electron transfer processes, and strategies to improve cell performance are discussed. Electron transport and trapping in the mesoporous oxide are discussed, and a novel method to probe the electrochemical potential (quasi Fermi level) of electrons in the DSC is described. The article concludes with an assessment of the prospects for future development of the DSC concept.

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“…Transient absorption experiments in the visible and infrared spectral regions have revealed that the electron injection process occurs on femtosecond to picosecond time scales. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Many of the studies reported to date have focused on the dynamics of electron injection for Ru(H 2 L′) 2 (NCS) 2 (the socalled "N3" sensitizer), where H 2 L′ is 4,4′-dicarboxylic acid-2,2′-bipyridine, adsorbed on nanocrystalline TiO 2 . [1][2][3][4][5][6][7][8][9] This system has been well-studied because Ru(H 2 L′) 2 (NCS) 2 adsorbed onto TiO 2 has been reported to produce 5-10% solar energy conversion efficiencies under Air Mass (AM) 1.5 conditions.…”

Section: Introductionmentioning

confidence: 99%

“…This injection process is a critical step in the production of photocurrent in dye-sensitized nanocrystalline TiO 2 solar cells. Transient absorption experiments in the visible and infrared spectral regions have revealed that the electron injection process occurs on femtosecond to picosecond time scales. − …”

Section: Introductionmentioning

confidence: 99%

Transient Absorption Spectroscopy of Ruthenium and Osmium Polypyridyl Complexes Adsorbed onto Nanocrystalline TiO₂ Photoelectrodes

et al. 2002

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Transient absorption spectroscopy has been used to probe the electron injection dynamics of transition metal polypyridyl complexes adsorbed onto nanocrystalline TiO 2 photoelectrodes. Experiments were performed on photoelectrodes coated with Ru(H 2 L′) 2 (CN) 2 , Os(H 2 L′) 2 (CN) 2 , Ru(H 2 L′) 2 (NCS) 2 , or Os(H 2 L′) 2 (NCS) 2 , where H 2 L′ is 4,4′-dicarboxylic acid-2,2′-bipyridine, to study how the excited-state energetics and the nature of the metal center affect the injection kinetics. All of these complexes exhibited electron injection dynamics on both the femtosecond and picosecond time scales. The femtosecond components were instrument-limited (<200 fs), whereas the picosecond components ranged from 3.3 ( 0.3 ps to 14 ( 4 ps (electron injection rate constants k 2 ′ ) (7.1-30) × 10 10 s -1). The picosecond decay component became more rapid as the formal excited-state reduction potential of the complex became more negative. Variable excitation wavelength studies suggest that femtosecond injection is characteristic of the nonthermalized singlet metal-to-ligand chargetransfer ( 1 MLCT) excited state, whereas picosecond injection originates from the lowest-energy 3 MLCT excited state. On the basis of these assignments, the smaller relative amplitude of the picosecond component for the Ru sensitizers suggests that electron injection from nonthermalized excited states competes more effectively with 1 MLCT f 3 MLCT conversion for the Ru sensitizers than for the Os sensitizers.

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Femtosecond Electron Transfer from the Excited State of Chemically Anchored Chromophores into the Empty Conduction Band of Nanocrystalline Spong-like TiO₂ Films*

Cited by 22 publications

References 17 publications

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Dye-sensitized nanocrystalline solar cells

Transient Absorption Spectroscopy of Ruthenium and Osmium Polypyridyl Complexes Adsorbed onto Nanocrystalline TiO₂ Photoelectrodes

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Femtosecond Electron Transfer from the Excited State of Chemically Anchored Chromophores into the Empty Conduction Band of Nanocrystalline Spong-like TiO2 Films*

Cited by 22 publications

References 17 publications

Spectral Sensitization of TiO2 Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Spectral Sensitization of TiO2 Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Dye-sensitized nanocrystalline solar cells

Transient Absorption Spectroscopy of Ruthenium and Osmium Polypyridyl Complexes Adsorbed onto Nanocrystalline TiO2 Photoelectrodes

Contact Info

Product

Resources

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Femtosecond Electron Transfer from the Excited State of Chemically Anchored Chromophores into the Empty Conduction Band of Nanocrystalline Spong-like TiO₂ Films*

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Spectral Sensitization of TiO₂ Nanocrystalline Electrodes with Aggregated Cyanine Dyes

Transient Absorption Spectroscopy of Ruthenium and Osmium Polypyridyl Complexes Adsorbed onto Nanocrystalline TiO₂ Photoelectrodes