Publications by 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, Shaik Mohammed Zakeeruddin, Jacques-Edouard Moser, Robin Humphry-Baker, Magdalena Anna Marszalek, Takeru Bessho, 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, Xiong Li, Takeru Bessho

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, Chenyi Yi, Takeru Bessho, 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, Shaik Mohammed Zakeeruddin, Jacques-Edouard Moser, Robin Humphry-Baker, Magdalena Anna Marszalek, Takeru Bessho, 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, Mohammad Khaja Nazeeruddin, Jacques-Edouard Moser, Jun Ho Yum, Arianna Marchioro, Thomas Moehl, Chenyi Yi, Takeru Bessho, Elham Ghadiri

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, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Guido Rothenberger, Efthimios Kaxiras, Takeru Bessho, 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, Jun Ho Yum, Takeru Bessho

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