Showing papers by "Michael Grätzel published in 1998"
TL;DR: A dye-sensitized heterojunction of TiO2 with the amorphous organic hole-transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (OMeTAD) was described in this article.
Abstract: Solar cells based on dye-sensitized mesoporous films of TiO2 arelow-cost alternatives to conventional solid-state devices1. Impressive solar-to-electrical energy conversion efficiencies have been achieved with such films when used in conjunction with liquid electrolytes2. Practical advantages may be gained by the replacement of the liquid electrolyte with a solid charge-transport material. Inorganic p-type semiconductors3,4 and organic materials5,6,7,8,9 have been tested in this regard, but in all cases the incident monochromatic photon-to-electron conversion efficiency remained low. Here we describe a dye-sensitized heterojunction of TiO2 with the amorphous organic hole-transport material 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (OMeTAD; refs. 10 and 11). Photoinduced charge-carrier generation at the heterojunction is very efficient. A solar cell based on OMeTAD converts photons to electric current with a high yield of 33%.
3,386 citations
TL;DR: A review of the recent applications of transition metal-to-ligand charge transfer (MLCT) and ligand-centered (π −π*) excited states of these complexes is given in this article.
1,375 citations
TL;DR: In this paper, density functional calculations of the (101) and (001) surfaces of the TiO 2 anatase at various coverages have been performed at both low and monolayer coverage.
Abstract: We present density functional calculations of ${\mathrm{H}}_{2}\mathrm{O}$ interacting with the (101) and (001) surfaces of ${\mathrm{TiO}}_{2}$ anatase at various coverages $\ensuremath{\theta}$. On the (101) surface, nondissociative molecular adsorption at fivefold coordinated Ti sites is favored at both low and monolayer coverage. On the (001) surface, for $\ensuremath{\theta}\ensuremath{\le}0.5$, ${\mathrm{H}}_{2}\mathrm{O}$ is adsorbed dissociatively, with an adsorption energy $\ensuremath{\Delta}{H}_{\mathrm{H},\mathrm{OH}}\ensuremath{\sim}1.6\mathrm{eV}$. At $\ensuremath{\theta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$, ${\mathrm{H}}_{2}\mathrm{O}$ can be adsorbed molecularly ( $\ensuremath{\Delta}{H}_{{\mathrm{H}}_{2}\mathrm{O}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.82\mathrm{eV}/\mathrm{molecule}$), but a state with half of the ${\mathrm{H}}_{2}\mathrm{O}$ adsorbed dissociatively and the other half H bonded in a ``second layer'' is energetically more favorable. These results are discussed in the context of the available experimental information.
870 citations
TL;DR: In this paper, a unique solar cell fabrication procedure has been developed using natural anthocyanin dyes extracted from berries, which can be reproduced with a minimum amount of resources in order to provide an interdisciplinary approach for lower-division undergraduate students learning the basic principles of biological extraction, physical chemistry, and spectroscopy as well as environmental science and electron transfer.
Abstract: A unique solar cell fabrication procedure has been developed using natural anthocyanin dyes extracted from berries. It can be reproduced with a minimum amount of resources in order to provide an interdisciplinary approach for lower-division undergraduate students learning the basic principles of biological extraction, physical chemistry, and spectroscopy as well as environmental science and electron transfer. Electron transfer is the basis of the energetics that drives the processes of life on Earth, occurring in both the mitochondrial membranes of living cells and in the thylakoid membranes of photosynthetic cells of green plants and algae (1). Although we depend on the petroleum and agricultural products of this electron and energy transfer, one of the greatest challenges of the 21st century is that we have yet to create devices that can be used to tap directly into the ultimate source of this energy on an economic scale. An experimental lab procedure was therefore created in order to illustrate the con...
306 citations
TL;DR: A monolayer of a phosphonated triarylamine adsorbed on nanocrystalline TiO 2, ZrO2, or Al2O3 film deposited on conducting glass displays reversible electrochemical and electrochromic behavior although the redox potential of the electroactive molecules lies in the forbidden band of the semiconducting or insulating oxides.
Abstract: A monolayer of a phosphonated triarylamine adsorbed on nanocrystalline TiO2, ZrO2, or Al2O3 film deposited on conducting glass displays reversible electrochemical and electrochromic behavior although the redox potential of the electroactive molecules (0.80 V vs NHE) lies in the forbidden band of the semiconducting or insulating oxides. The mechanism of charge transport was found to involve hole injection from the conducting support followed by lateral electron hopping within the monolayer. The apparent diffusion coefficient ranged from 2.8 × 10-12 m2 s-1 in the neat 1-ethyl-2-methylimidazolium bis(trifluoromethylsulfonyl)imide (EtMeIm+Tf2N-) to 1.1 × 10-11 m2 s-1 in acetonitrile + 2 M EtMeIm+Tf2N-. A percolation threshold for electronic conductivity was found at a surface coverage corresponding to 50% of a full monolayer.
203 citations
TL;DR: In this article, the axial pyridine 3,4-dicarboxylic acid ligands are anchored to nanocrystalline TiO2 films through axial poly(3,4)-poly(1,8,11,15,18,22,25,25 octamethyl-phthalocyaninato) ligands.
165 citations
Journal Article•
TL;DR: In this article, the axial pyridine 3,4-dicarboxylic acid ligands are anchored to nanocrystalline TiO2 films through axial poly(3,4)-poly(1,8,11,15,18,22,25,25 octamethyl-phthalocyaninato) ligands.
146 citations
TL;DR: In this paper, the steady-state mass transport in a thin-layer cell configuration involving an electrochemically inactive mesoporous colloidal film was modeled and the limiting currents of an iodine containing electrolyte can be predicted, as a function of the film porosity.
Abstract: By modeling the steady-state mass transport in a thin-layer cell configuration involving an electrochemically inactive mesoporous colloidal film, the limiting currents of an iodine containing electrolyte can be predicted, as a function of the film porosity. The porosity of the layer is then determined by best fit of the porosity parameter in the model, given the experimentally determined limiting currents. Satisfactory agreement is found with the porosity values obtained by BET measurements. In photoelectrochemical cell applications such as dye sensitized nanocrystalline photoelectrodes for solar energy conversion devices, the porosities of the dye loaded films of e.g. anatase TiO2 play an essential role with respect to their efficiency. In particular, the findings of this work demonstrate that the presence of adsorbed sensitizer cis-(SCN-)2 bis(2,2‘-bipyridyl-4,4‘-dicarboxylate)ruthenium(II) in TiO2 colloidal films appears to decrease the original naked film porosity by up to 30%. This depends on the ini...
116 citations
Patent•
07 May 1998TL;DR: In this article, a photoensitizer complex of formulae (Ia) MX3Lt or (Ib) MXYLt is defined, in which each X is a co-ligand independently selected from NCS?-, Cl-, Br-, I-, CN-, NCO-, H?2O, NCN2-, pyridine unsubstituted or substituted by at least one group selected from vinyl, primary, secondary or tertiary amine, OH and C?1-30? alkyl, preferably nCS?-?; and
Abstract: A photosensitizer complex of formulae (Ia) MX3Lt or (Ib) MXYLt in which M is a transition metal selected from ruthenium, osmium, iron, rhenium and technetium, preferably ruthenium or osmium; each X is a co-ligand independently selected from NCS?-, Cl-, Br-, I-, CN-, NCO-, H?2O, NCN2-, pyridine unsubstituted or substituted by at least one group selected from vinyl, primary, secondary or tertiary amine, OH and C?1-30? alkyl, preferably NCS?-?; and L?t? is a tridentate ligand comprising heterocycles such as pyridine, thiophene, imidazole, pyrazole, triazole, carrying at least one carboxylic, phosphoric, hydoxamic acid or a chelating group. A photovoltaic cell comprising an electrically conductive layer deposited on a support to which at least one titanium dioxide layer has been applied and, as a photosensitizer applied to the titanium dioxide layer, a photosensitizer complex of formulae (Ia) or (Ib) as specified above.
115 citations
TL;DR: In this paper, a general method for the synthesis of trisheteroleptic ruthenium(II) complexes of the type [Ru(dcbpy)(dmbpy)(ddtc)] was reported, where the ligands were introduced sequentially.
Abstract: A general method for the synthesis of tris-heteroleptic ruthenium(II) complexes of the type [Ru(dcbpy)(dmbpy)(ddtc)] (3) and [Ru(dcbpy)(dmbpy)(NCS)2] (4) is reported, where the ligands (dcbpy = 4,4‘-dicarboxy-2,2‘-bipyridine, dmbpy = 4,4‘-dimethyl-2,2‘-bipyridine, and ddtc = diethyldithiocarbamate) are introduced sequentially. The complexes have been characterized by UV/visible, emission, IR, Raman and NMR spectroscopies and cyclic voltammetry. The effect of pH on the absorption spectra and luminescence behavior of these complexes consisting of protonatable ligands has been investigated in a water/ethanol solvent mixture by pH titration. The dissociation of protons is in sequential steps (pKa = 3.5 and 1.8). The excited-state pKa values are more basic than the ground-state pKa values. Resonance Raman spectra of these complexes strongly suggest that the lowest-energy metal-to-ligand charge-transfer transition bands are localized on the dcbpy ligand. The molecular crystal structure of 3 and the performance ...
102 citations
TL;DR: In this article, the surface of the TiO2 anatase polymorph and its interaction with small Bronsted acid molecules (H2O, H2S and HI) were studied by means of first-principles molecular dynamics calculations.
TL;DR: In this article, a new class of ruthenium(II) complexes containing carboxylated 1,10-phenanthroline were synthesized, and the overall solar-to-electric power conversion efficincy was obtained at AM-1.5 (100 mW/cm2).
Abstract: A new class of ruthenium(II) complexes containing carboxylated 1,10-phenanthroline were synthesized. Photosensitization of nanocrystalline TiO2 electrode by bis(tetrabutylammonium)dihydronium cis-dithiocyanato bis(4,7-dicarboxy-1,10-phenanthroline)ruthenium(II) showed a high incident photon-to-current conversion efficiency (IPCE: 70% at 540 nm). The overall solar-to-electric power conversion efficincy of 6.1% was obtained at AM-1.5 (100 mW/cm2).
TL;DR: In this paper, the authors present a Web of Science Record created on 2006-02-21, modified on 2017-05-12, with the purpose of improving the quality of the record.
TL;DR: In this paper, the energy diagram of an organic semiconductor film on SnO2:F was constructed by surface photovoltage spectroscopy (SPS) using surface-mounted sensors.
TL;DR: The attachment of a tetradecyl chain to the ionophore 18-crown-6 leads to a stronger interaction with a supported lipid monolayer as discussed by the authors, which is used to produce ionophores contg. at the surface of an electrode.
Abstract: The attachment of a tetradecyl chain to the ionophore 18-crown-6 leads to a stronger interaction with a supported lipid monolayer. Some C14-18-crown-6 mols. introduced in the aq. phase are incorporated in the phospholipid membrane. This process is used to produce ionophore contg. lipid monolayers of detd. compn. at the surface of an electrode. The ionophore content and the sensitivity to K+ of these layers are detd. by capacitance measurements. [on SciFinder (R)]
TL;DR: This poster presents a probabilistic procedure to estimate the total number of particles in the Higgs boson genome and determines the number of “good” and “bad” particles.
Abstract: Reference LPI-CHAPTER-1998-031View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12