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Michael Graetzel

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Publications associées (1 223)

Enhanced light harvesting in mesoporous TiO2/P3HT hybrid solar cells using a porphyrin dye

Michael Graetzel, Shaik Mohammed Zakeeruddin, Soo-Jin Moon, Kevin Sivula

We report panchromatic light harvesting in hybrid TiO2/P3HT photovoltaic devices using a porphyrin dye that complements the light absorption of P3HT. The high short circuit photocurrent (12.1 mA cm(-2)) obtained is found to be due, in part, to Forster reso ...

Royal Society of Chemistry2011

Cobalt Redox Mediators for Ruthenium-Based Dye-Sensitized Solar Cells: A Combined Impedance Spectroscopy and Near-IR Transmittance Study

Michael Graetzel, Shaik Mohammed Zakeeruddin, Yuhang Liu

Dye-sensitized solar cells with power conversion efficiencies of up to 6.5% have been fabricated using a cobalt trisbipyridyl redox mediator with the cis-diisothiocyanato-(2,2'-bipyridyl-4,4'-dicarboxylic acid)-(2,2'-bipyridyl-4,4'-dinonyl) ruthenium(II) ( ...

American Chemical Society2011

Organic dyes incorporating low-band-gap chromophores based on pi-extended benzothiadiazole for dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Filippo de Angelis

A series of new it-conjugated organic dyes (HKK-BTZ1, HKK-BTZ2, HKK-BTZ3 and HKK-BTZ4), comprising triphenylamine (TPA) moieties as the electron donor and benzothiadiazole moieties as the electron acceptor/anchoring groups, was synthesized for the use in d ...

Elsevier2011

Dynamics of photogenerated holes in nanocrystalline alpha-Fe2O3 electrodes for water oxidation probed by transient absorption spectroscopy

Michael Graetzel, Kevin Sivula

Transient absorption spectroscopy on the mu s-s time scale is used to monitor the yield and decay dynamics of photogenerated holes in nanocrystalline hematite photoanodes. In the absence of a positive applied bias, these holes are observed to undergo rapid ...

Royal Society of Chemistry2011

A new familiy of heteroleptic ruthenium(II) polypyridyl complexes for sensitization of nanocrystalline TiO2 films

Michael Graetzel, Mohammad Khaja Nazeeruddin, Takeru Bessho, Jun Ho Yum

Two new heteroleptic ruthenium(II) photosensitizers that contains 2,2';6,2 ''-terpyridine with extended p-conjugation with donor groups, a 4,4'-dicarboxylic acid-2,2'-bipyridine anchoring ligand and a thiocyanate ligand have been designed, synthesized and ...

Royal Society of Chemistry2011

Increasing the efficiency of zinc-phthalocyanine based solar cells through modification of the anchoring ligand

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

Several zinc-based phthalocyanines have been synthesized and used in Dye-Sensitized Solar Cells (DSSC). The results have been compared with the standard TT1 phthalocyanine, which shows good light-to-energy conversion efficiencies in comparison with other I ...

2011

Influence of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells employing cobalt redox shuttles

Michael Graetzel, Mohammad Khaja Nazeeruddin, Julian Burschka, Chenyi Yi, Hoi Nok Tsao

We highlight the effect of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells based on two cobalt redox shuttles, namely cobalt(III/II) tris(2,2'-bipyridine) and cobalt(III/II) tris(1,10-phenanthroline). Highl ...

2011

Evolution of an Oxygen Near-Edge X-ray Absorption Fine Structure Transition in the Upper Hubbard Band in alpha-Fe2O3 upon Electrochemical Oxidation

Michael Graetzel, Kevin Sivula, Artur Braun

Electrochemical oxidation of hematite (alpha-Fe2O3) nanoparticulate films at 600 mV vs Ag+/AgCl in KOH electrolyte forms a species at the hematite surface which causes a new transition in the upper Hubbard band between the Fe(3d)-O(2p) state region and the ...

American Chemical Society2011

A Thiophene-Based Anchoring Ligand and Its Heteroleptic Ru(II)-Complex for Efficient Thin-Film Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Soo-Jin Moon, Mingkui Wang, Nuttapol Pootrakulchote, Amaresh Mishra

A novel heteroleptic Ru-II complex (BTC-2) employing 5,5'-(2,2'-bipyridine-4,4'-diyl)-bis(thiophene-2-carboxylic acid) (BTC) as the anchoring group and 4,4'-dinonyl-2,2'-bipiridyl and two thiocyanates as ligands is prepared. The photovoltaic performance an ...

Wiley-Blackwell2011

Toward Interaction of Sensitizer and Functional Moieties in Hole-Transporting Materials for Efficient Semiconductor-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yonghui Lee

Sb2S3-sensitized mesoporous-TiO2 solar cells using several conjugated polymers as hole-transporting materials (HTMs) are fabricated. We found that the cell performance was strongly cc rrelated with the chemical interaction at the interface of Sb2S3 as sens ...

American Chemical Society2011

Application of Ionic Liquids Containing Tricyanomethanide [C(CN)(3)](-) or Tetracyanoborate [B(CN)(4)](-) Anions in Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Rosario Scopelliti, Paul Joseph Dyson, Zhaofu Fei, Magdalena Anna Marszalek

A series of novel ionic liquids composed of imidazolium, pyridinium, pyrrolidinium, and ammonium cations with tricyanomethanide or tetracyanoborate anions were prepared. The ionic liquids were characterized by NMR and IR spectroscopy and ESI-mass spectrome ...

2011

Ga3+ and Y3+ Cationic Substitution in Mesoporous TiO2 Photoanodes for Photovoltaic Applications

Michael Graetzel, Aravind Kumar Chandiran, Lioz Etgar

The optoelectronic properties of transparent nanocrystalline TiO2 films were modified by the incorporation of a low level of Ga3+ or Y3+ cations. After optimizing their relative concentration level, we were able to increase in a noticeable manner the power ...

American Chemical Society2011

Photo-assisted electrodeposition of cobalt-phosphate (Co-Pi) catalyst on hematite photoanodes for solar water oxidation

Michael Graetzel, Maurin Cornuz, Kevin Sivula

A photo-assisted electrodeposition approach was used to deposit a cobalt-phosphate water oxidation catalyst ("Co-Pi") onto recently improved dendritic mesostructures of alpha-Fe2O3. A comparison between this approach, electrodeposition of Co-Pi, and Co2+ w ...

2011

A High-Efficiency Panchromatic Squaraine Sensitizer for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Rebecca Hill, Amalie Dualeh

Wiley-VCH Verlag GmbH2011

A bright tetranuclear iridium(III) complex

Michael Graetzel, Mohammad Khaja Nazeeruddin, Davide Di Censo, Rosario Scopelliti

A cyclic tetranuclear cyclometallated iridium(III) complex using cyanide anions as bridging ligands and displaying a tetrahedrally distorted square geometry has been obtained with high yield; photo- and electrochemical characterizations show that most inte ...

Royal Society of Chemistry2011

Stable dye-sensitized solar cells based on organic chromophores and ionic liquid electrolyte

Pascal Comte, Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin

A series of polyene-diphenylaniline based organic dyes (coded as D5, D7, D9 and D11) have been reported for the application in ionic liquid electrolyte based dye-sensitized solar cells. The effects of substitution of organic dyes on the photovoltaic perfor ...

2011

Polypyridyl Ru(II)-sensitizers with extended pi-system enhances the performance of dye sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

New polypyridyl ruthenium(II) complexes "cis-Ru(4,4'-dimesity1-2,2'-bipyridine) (Ln) (NCS)(2) H102" and "cis-Ru(4,4'-bis(2,3,6-tri-isopropylphenyl)-2,2'-bipyridine) (Ln) (NCS)(2) H105", where Ln = 4,4'-dicarboxylic acid-2,2'-bipyridine; were synthesized an ...

Elsevier2011

An efficient DSSC based on ZnO nanowire photo-anodes and a new D-pi-A organic dye

Michael Graetzel, Shaik Mohammed Zakeeruddin, Lioz Etgar, Peng Wang

Zinc oxide-titanium dioxide core-shell nanowire dye-sensitised solar cells have been synthesised, making use of a recently developed organic dye and iodide-based electrolyte. We have been able to demonstrate a cell efficiency of 2.53% under AM1.5 for our s ...

2011

Convenient synthesis of tridentate 2,6-di(pyrazol-1-yl)-4-carboxypyridine and tetradentate 6,6 '-di(pyrazol-1-yl)-4,4 '-dicarboxy-2,2 '-bipyridine ligands

Michael Graetzel, Mohammad Khaja Nazeeruddin

Citrazinic acid is used as a convenient starting material for both tridentate 2,6-di(pyrazol-1-yl)-pyridine and tetradentate 6,6'-di(pyrazol-1-yl)-2,2'-bipyridine ligands containing carboxylic groups useful for further anchoring of sensitizer on TiO2 for d ...

Elsevier2011

Depleted Bulk Heterojunction Colloidal Quantum Dot Photovoltaics

Michael Graetzel, Lioz Etgar

The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar ...

Wiley2011

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