Publications de Yongjoo Kim | EPFL Graph Search

Influence of the Donor Size in D-pi-A Organic Dyes for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Pascal Comte, Thomas Moehl, Chenyi Yi, Joël Teuscher, Thomas Wesley Holcombe, Jiabao Yang, Yongjoo Kim

We report two new molecularly engineered push-pull dyes, i.e., YA421 and YA422, based on substituted quinoxaline as a pi-conjugating linker and bulky-indoline moiety as donor and compared with reported IQ4 dye. Benefitting from increased steric hindrance w ...

American Chemical Society2014

Panchromatic light harvesting by dye- and quantum dot-sensitized solar cells

Michael Graetzel, Jun Ho Yum, Robin Humphry-Baker, Yongjoo Kim

A PbS:Hg quantum dots-sensitized solar cell (QDSC) combined with a dye-sensitized solar cell (DSC) to harvest panchromatic solar spectrum from the visible light to the near IR is demonstrated. We use the filter to split the solar energy and access the tota ...

Pergamon-Elsevier Science Ltd2014

Acetylene-bridged dyes with high open circuit potential for dye-sensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Pascal Comte, Thomas Moehl, Fabrizio Giordano, Aswani Yella, Yongjoo Kim, Chi-Lun Mai

A series of simple metal-free organic dyes MS1-MS3 have been designed and synthesized, and their optical, electrochemical, and photovoltaic properties were investigated. The molecular structures are based on a push-pull framework with a triphenylamine, nap ...

RSC Publishing2014

Molecular Engineering of Phthalocyanine Sensitizers for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Simon Mathew, Yongjoo Kim

A series of novel near-infrared-absorbing zinc phthalocyanines bearing donor-chromophore-acceptor/anchoring groups have been synthesized to investigate their influence on solar cell performance. With the aim of extending the absorption spectra while mainta ...

American Chemical Society2014

Facile synthesis of a bulky BPTPA donor group suitable for cobalt electrolyte based dye sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Peng Gao, Thomas Wesley Holcombe, Yongjoo Kim

An efficient synthesis of N-(2 ',4 '-bis(hexyloxy)-[1,1 '-biphenyl]-4-yl)-N-(4-bromophenyl)-2 ',4 '-bis(hexyloxy)-[ 1,1 '-biphenyl]-4-amine (BPTPA donor, 5) was developed based on a new 4-step synthetic route. The BPTPA donor is used to quickly access two ...

Royal Society of Chemistry2013

Blue-Coloured Highly Efficient Dye-Sensitized Solar Cells by Implementing the Diketopyrrolopyrrole Chromophore

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Thomas Moehl, Joël Teuscher, Kasparas Rakstys, Thomas Wesley Holcombe, Yongjoo Kim

The paradigm shift in dye sensitized solar cells (DSCs) - towards donor-pi bridge-acceptor (D-pi-A) dyes - increases the performances of DSCs and challenges established design principles. Framed by this shifting landscape, a series of four diketopyrrolopyr ...

Nature Publishing Group2013

Diketopyrrolopyrrole-based sensitizers for dye-sensitized solar cell applications: anchor engineering

Michael Graetzel, Jun Ho Yum, Kasparas Rakstys, Thomas Wesley Holcombe, Yongjoo Kim

A series of donor-chromophore-anchor (D-C-A) sensitizers comprising the diketopyrrolopyrrole (DPP) chromophore were synthesized and tested in both I-3(-)/I- and Co(bpy) redox shuttle DSC devices. The dye series was strategically designed to elucid ...

Royal Society of Chemistry2013

Towards high-performance DPP-based sensitizers for DSC applications

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Kasparas Rakstys, Thomas Wesley Holcombe, Yongjoo Kim, Junghyun Yoon

A novel, asymmetric DPP bridge/core was synthesized and tested in DSC devices. By desymmetrising the DPP core/bridge, a remarkable IPCE of >80% and a maximum power conversion efficiency of 7.7% were achieved. With the use of a wide-bandgap co-sensitizer, 8 ...

Royal Society of Chemistry2012

Light-emitting material

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yongjoo Kim

This invention pertains to light emitting materials comprising novel ortho-metalated transition metal complexes [C^N]2ML, comprising chelate monoionic ligands (L), also called ancillary ligands. It has been surprisingly found that when the ancillary ligand ...

2007