Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes

Nazeeruddin, Md. K.; Kay, Andreas; Rodicio, I.; Humphry‐Baker, Robin; Mueller, E.; Liska, Paul; Vlachopoulos, Nikolaos; Gräetzel, Michael

doi:10.1021/ja00067a063

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“…Electron transport through the nanoparticle network occurs by trap-mediated diffusion, a slow mechanism (with electron escape times of 1-10 ms for ∼10-µm-thick TiO 2 films) 1 that is nonetheless efficient for TiO 2 cells that use the traditional I -/I 3 -redox couple in a liquid electrolyte. State-of-the-art liquid-electrolyte TiO 2 DSCs show near-unity external quantum efficiency at wavelengths near the absorption maximum of the dye. 2 Such efficient charge collection is possible despite slow electron transport because of the order-of-magnitude slower recombination of photoinjected electrons with I 3 -in the electrolyte.…”

Section: Introductionmentioning

confidence: 99%

“…Over the past five years, many studies have described the effects of overcoating nanocrystalline TiO 2 [27][28][29][30][31][32] In principle, an oxide shell can suppress recombination by (i) introducing an energy barrier that increases the physical separation between photoinjected electrons and the oxidized redox species in the electrolyte, (ii) forming a tunneling barrier that corrals electrons within the conducting cores of the nanoparticle film, or (iii) passivating recombination centers on the oxide surface. A lower rate of recombination appears as a smaller dark current (J dark ), which can increase the open-circuit voltage (and fill factor) of a DSC according to the general expression V OC ) nV th ln((J SC /J dark ) + 1), where n is the diode ideality factor and V th is the thermal voltage.…”

Section: Introductionmentioning

confidence: 99%

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ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

et al. 2006

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We describe the construction and performance of dye-sensitized solar cells (DSCs) based on arrays of ZnO nanowires coated with thin shells of amorphous Al 2 O 3 or anatase TiO 2 by atomic layer deposition. We find that alumina shells of all thicknesses act as insulating barriers that improve cell open-circuit voltage (V OC ) only at the expense of a larger decrease in short-circuit current density (J SC ). However, titania shells 10-25 nm in thickness cause a dramatic increase in V OC and fill factor with little current falloff, resulting in a substantial improvement in overall conversion efficiency, up to 2.25% under 100 mW cm -2 AM 1.5 simulated sunlight. The superior performance of the ZnO-TiO 2 core-shell nanowire cells is a result of a radial surface field within each nanowire that decreases the rate of recombination in these devices. In a related set of experiments, we have found that TiO 2 blocking layers deposited underneath the nanowire films yield cells with reduced efficiency, in contrast to the beneficial use of blocking layers in some TiO 2 nanoparticle cells. Raising the efficiency of our nanowire DSCs above 2.5% depends on achieving higher dye loadings through an increase in nanowire array surface area.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

et al. 2006

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“…Numerous reports describe the synthesis of such composite materials, with particular emphasis on immobilization of noble metal nanoparticles on oxides such as SiO 2 [1][2][3], TiO 2 [4][5][6][7][8][9][10] and Al 2 O 3 [11][12][13][14][15][16]. These oxides are of interest due to their ready availability, ease of handling, low toxicity and low cost.…”

Section: Introductionmentioning

confidence: 99%

Titania–silver and alumina–silver composite nanoparticles: Novel, versatile synthesis, reaction mechanism and potential antimicrobial application

Bala

Armstrong

Laffir

et al. 2011

Journal of Colloid and Interface Science

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“…9 Ruthenium complexes were adsorbed onto nanocrystalline titanium dioxide films from 0.3 mM N3 solutions in ethanol or 0.5 mM N719 solutions in acetonitrile/tert-butyl alcohol (1:1) solvent mixture for 12 h. 3,10 Dyed samples displayed typically an OD of 1.5 at λ ) 534 nm. They were covered with a film of the redoxinactive ionic liquid (1-ethyl-2-methylimidazoliumbis(trifluoromethylsulfonyl)imide).…”

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confidence: 99%

Rationale for Kinetic Heterogeneity of Ultrafast Light-Induced Electron Transfer from Ru(II) Complex Sensitizers to Nanocrystalline TiO₂

2005

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The conversion of light into electricity in dye-sensitized solar cells (DSC) is initiated by the charge injection from an electronically excited dye molecule into the conduction band of a wide band gap oxide semiconductor. 1,2 Because of their successful use in such devices, Ru(II) polypyridyl complex dyes adsorbed on nanocrystalline titanium dioxide films have been regarded as model systems for the experimental study of the ultrafast dynamics of interfacial light-induced electron transfer (ET). Yet, the complex kinetic behavior observed for the charge injection process in this case has prevented the development of a satisfying kinetic model and has led to often contradicting conclusions. One of the most successful sensitizers used up to now for DSC is the N3 ruthenium(II) complex (Ru II (dcbpyH 2 ) 2 (NCS) 2 ), which is known to inject an electron into TiO 2 with practically unit quantum efficiency. 3 The kinetics of ET from N3 have been under study for the past decade. [2][3][4][5][6][7][8] In a widely referred to study, in particular, Benkö et al. reported the charge injection process to take place with a biphasic kinetics. 5 The first ultrafast component was estimated to have a rise time of 28 fs and the second multiexponential part to occur within the 1-50 ps time range. This behavior was rationalized in terms of a two-state mechanism, the fast and slow components being attributed to the injection from the singlet and triplet excited states of the ruthenium complex, respectively. Although several other studies confirm the presence of the slower component, its relative contribution ranges from <5 to 65%, and the time constants vary from 0.7 to 100 ps, with a marked nonexponential behavior and dependence upon experimental conditions. [4][5][6][7][8][9] This discrepancy actually questions the proposed interpretation. In other published works, the kinetic heterogeneity of the charge injection was attributed to dye molecules adsorbed on energetically diverse sites or in various spatial configurations at the surface of the nanocrystalline titania films. 9 Here, we show that the slow component of electron injection arises from sensitizer molecules that are loosely attached onto the surface or are present in an aggregated form. A monophasic ET with a rise time shorter than 20 fs is observed when the formation of aggregates is prevented and the sensitizer is adsorbed as a monolayer on the surface of TiO 2 nanocrystals.Kinetic measurements employed a commercially available N3 dye (Solaronix, Switzerland) and also home-synthesized N3 and its doubly deprotonated derivative (Bu 4 N) 2 [Ru(dcbpyH) 2 (NCS) 2 ] (N719). 9 Ruthenium complexes were adsorbed onto nanocrystalline titanium dioxide films from 0.3 mM N3 solutions in ethanol or 0.5 mM N719 solutions in acetonitrile/tert-butyl alcohol (1:1) solvent mixture for 12 h. 3,10 Dyed samples displayed typically an OD of 1.5 at λ ) 534 nm. They were covered with a film of the redoxinactive ionic liquid (1-ethyl-2-methylimidazoliumbis(trifluoromethylsulfonyl)imide). 11 The f...

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Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes

Cited by 5,911 publications

References 0 publications

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

Titania–silver and alumina–silver composite nanoparticles: Novel, versatile synthesis, reaction mechanism and potential antimicrobial application

Rationale for Kinetic Heterogeneity of Ultrafast Light-Induced Electron Transfer from Ru(II) Complex Sensitizers to Nanocrystalline TiO₂

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Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes

Cited by 5,911 publications

References 0 publications

ZnO−Al2O3 and ZnO−TiO2 Core−Shell Nanowire Dye-Sensitized Solar Cells

ZnO−Al2O3 and ZnO−TiO2 Core−Shell Nanowire Dye-Sensitized Solar Cells

Titania–silver and alumina–silver composite nanoparticles: Novel, versatile synthesis, reaction mechanism and potential antimicrobial application

Rationale for Kinetic Heterogeneity of Ultrafast Light-Induced Electron Transfer from Ru(II) Complex Sensitizers to Nanocrystalline TiO2

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Product

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ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

ZnO−Al₂O₃ and ZnO−TiO₂ Core−Shell Nanowire Dye-Sensitized Solar Cells

Rationale for Kinetic Heterogeneity of Ultrafast Light-Induced Electron Transfer from Ru(II) Complex Sensitizers to Nanocrystalline TiO₂