Publications de Takeru Bessho | EPFL Graph Search

Effect of Extended π-Conjugation of the Donor Structure of Organic D–A−π–A Dyes on the Photovoltaic Performance of Dye-Sensitized Solar Cells

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Takeru Bessho, Magdalena Anna Marszalek, Mateusz Barnaba Wielopolski

Two new D−A−π-spacer−A organic dyes, KM-10 and KM-11, containing a benzothiadiazole unit in a π-spacer and a cyanoacrylic acid as an acceptor have been synthesized and tested as sensitizers in dye-sensitized solar cells. Structural variations of the donor ...

Amer Chemical Soc2014

Interpretation of Optoelectronic Transient and Charge Extraction Measurements in Dye-Sensitized Solar Cells

Michael Graetzel, Takeru Bessho, Xiong Li

Tools that assess the limitations of dye sensitized solar cells (DSSCs) made with new materials are critical for progress. Measuring the transient electrical signals (voltage or current) after optically perturbing a DSSC is an approach which can give infor ...

Wiley-Blackwell2013

A new generation of platinum and iodine free efficient dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Takeru Bessho, Chenyi Yi, Julien Edouard Frey

We report a series of cobalt complexes with various polypyridyl ligands, where the oxidation potential is tuned from 0.17 to 0.34 V vs. ferrocene. The highest occupied molecular orbitals (HOMO) of the cobalt complexes were stabilized by adding electron acc ...

2012

Influence of the Anchoring Modes on the Electronic and Photovoltaic Properties of D−π–A Dyes

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Takeru Bessho, Magdalena Anna Marszalek, Mateusz Barnaba Wielopolski

Five new donor−π-bridge−acceptor (D−π−A) organic sensitizers with cyano and/or triple bond substituted benzoic acid as acceptor/anchoring groups were synthesized and tested for their performance in dye-sensitized solar cells (DSCs). The systematic incorpor ...

Amer Chemical Soc2012

A cobalt complex redox shuttle for dye-sensitized solar cells with high open-circuit potentials

Michael Graetzel, Jacques-Edouard Moser, Mohammad Khaja Nazeeruddin, Arianna Marchioro, Takeru Bessho, Jun Ho Yum, Elham Ghadiri, Thomas Moehl, Chenyi Yi

Dye-sensitized solar cells are a promising alternative to traditional inorganic semiconductor- based solar cells. Here we report an open-circuit voltage of over 1,000 mV in mesoscopic dye- sensitized solar cells incorporating a molecularly engineered cobal ...

Nature Research2012

Light scattering enhancement from sub-micrometer cavities in the photoanode for dye-sensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Takeru Bessho, Nripan Mathews

A simple cell architecture that achieves enhanced light harvesting with less dye quantity while simultaneously improving the power conversion efficiency (PCE) of dye-sensitized solar cells is presented. Polystyrene (PS) spheres of sub-micrometer size were ...

Royal Society of Chemistry2012

D-pi-A Dye System Containing Cyano-Benzoic Acid as Anchoring Group for Dye-Sensitized Solar Cells

Michael Graetzel, Guido Rothenberger, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Takeru Bessho, Efthimios Kaxiras, Sheng Meng

A D-pi-A dye (KM-1) incorporating cyanobenzoic acid as a new acceptor/anchoring group has been synthesized for dye-sensitized solar cells (DSCs) with a high molar extinction coefficient of 66 700 M-1 cm(-1) at 437 nm. Theoretical calculations show that the ...

American Chemical Society2011

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

Highly Efficient Mesoscopic Dye-Sensitized Solar Cells Based on Donor-Acceptor-Substituted Porphyrins

Michael Graetzel, Shaik Mohammed Zakeeruddin, Takeru Bessho

To dye for: A porphyrin chromophore, which is integrated into a donor-acceptor dye as a π-conjugated bridge (see picture), exhibits an unprecedented efficiency of 11 □ % when used as a photosensitizer in a double-layer TiO2 film. A greatly enhanced photovo ...

Wiley-VCH Verlag GmbH2010

New Paradigm in Molecular Engineering of Sensitizers for Solar Cell Applications

Michael Graetzel, Mohammad Khaja Nazeeruddin, Ursula Röthlisberger, Ivano Tavernelli, Matteo Guglielmi, Takeru Bessho

A novel thiocyanate-free cyclometalleted ruthenium sensitizer for solar cells is designed and developed. Upon anchoring to nanocrystalline TiO2 films, it exhibits a remarkable incident monochromatic photon-to-current conversion efficiency of 83%. The solar ...

2009

Regenerative PbS and CdS Quantum Dot Sensitized Solar Cells with a Cobalt Complex as Hole Mediator

Pascal Comte, Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Peter Chen, Takeru Bessho, Soo-Jin Moon, Kevin Sivula

Metal sulfide (PbS and CdS) quantum dots (QDs) were prepared over mesoporous TiO2 films by improved successive ionic layer adsorption and reaction (SILAR) processes. The as-prepared QD-sensitized electrodes were combined with a cobalt complex redox couple ...

2009

An element of surprise - efficient copper-functionalized dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Takeru Bessho

Dye-sensitized solar cells with carboxylate-derivatized {(CuL2)-L-1} complexes are surprisingly efficient and offer a long-term alternative approach to ruthenium-functionalized systems. ...

Royal Society of Chemistry2008

Takeru Bessho

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