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Chenyi Yi

Cette personne n’est plus à l’EPFL

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Publications associées (43)

Enhancing the Stability of Porphyrin Dye-Sensitized Solar Cells by Manipulation of Electrolyte Additives

Michael Graetzel, Shaik Mohammed Zakeeruddin, Paul Joseph Dyson, Chenyi Yi, Hoi Nok Tsao, Pui Shan Genevieve Lau

The use of porphyrin-based photosensitizers with superior light-harvesting properties has enabled the power conversion efficiency of dye-sensitized solar cells (DSCs) to reach 13% under full sun illumination. However, a major limitation of such devices cor ...

Wiley-V C H Verlag Gmbh2015

Anthanthrene dye-sensitized solar cells: influence of the number of anchoring groups and substitution motif

Michael Graetzel, Michele Cascella, Chenyi Yi, Martin Peter Bircher

Four new dye molecules comprising an anthanthrene core, thiophene-cyanoacrylic acid electron acceptor and triphenylamine (TPA) electron donor units were prepared. Thereby, the substitution pattern at the anthanthrene core has been varied systematically. Th ...

RSC Publishing2015

Improved performance and stability of perovskite solar cells by crystal crosslinking with alkylphosphonic acid omega-ammonium chlorides

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Manuel Tschumi, Chenyi Yi, Mohammad Ibrahim Dar, Xiong Li, Jingshan Luo

In the past few years, organic-inorganic halide perovskites have rapidly emerged as promising materials for photovoltaic applications, but simultaneously achieving high performance and long-term stability has proved challenging. Here, we show a one-step so ...

Nature Publishing Group2015

A quinoxaline-fused tetrathiafulvalene-based sensitizer for efficient dye-sensitized solar cells

Michael Graetzel, Michele Cascella, Chenyi Yi, Jiabao Yang, Martin Peter Bircher

A new quinoxaline-fused tetrathiafulvalene-based sensitizer has been prepared and characterized. The resulting power conversion efficiency of 6.47% represents the best performance to date for tetrathiafulvalene-sensitized solar cells. ...

Royal Society of Chemistry2014

High efficiency Porphyrin Sensitized Mesoscopic Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Joël Teuscher, Chenyi Yi, Fabrizio Giordano

Dye-Sensitized Solar Cells (DSSC) represents a reliable technology, ready for the market and able to compete with silicon solar cells for specific fields of application. Porphyrin dyes allow reaching high power conversion efficiency in conjunction with cob ...

Spie-Int Soc Optical Engineering2014

Extended pi-Bridge in Organic Dye-Sensitized Solar Cells: the Longer, the Better?

Michael Graetzel, Mohammad Khaja Nazeeruddin, Chenyi Yi, Hoi Nok Tsao, Peng Gao

The elongation of pi-conjugated bridges between the donor (D) and the acceptor (A) represents a feasible strategy towards enhancement of light-harvesting in both breadth and depth of organic D-pi-A dyes suitable for nanocrystalline TiO2-based dye-sensitize ...

Wiley-VCH Verlag Berlin2014

Quantum-Confined ZnO Nanoshell Photoanodes for Mesoscopic Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Aravind Kumar Chandiran, Aswani Yella, Chenyi Yi, Mojtaba Abdi Jalebi, Mohammad Ibrahim Dar

We present a photoanode for dye-sensitized solar cell (DSC) based on ZnO nanoshell deposited by atomic layer deposition at 150°C, on a mesoporous insulating template. An ultrathin layer of ZnO between 3 and 6 nm, which exhibits quantum confinement effect, ...

American Chemical Society2014

Electronic tuning effects via pi-linkers in tetrathiafulvalene-based dyes

Michael Graetzel, Chenyi Yi

Four new tetrathiafuIvalene (TTF)-based dyes featured with a donor-bridge-acceptor (D-pi-A) structure were synthesized and characterized. ALL of them undergo two reversible oxidations to form stable radical cation and dication species. The eIectronic inter ...

Royal Society of Chemistry2014

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

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

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

Influence of Structural Variations in Push-Pull Zinc Porphyrins on Photovoltaic Performance of Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Chenyi Yi, Hoi Nok Tsao, Fabrizio Giordano

We designed and synthesized two new zinc porphyrin dyes for dye-sensitized solar cells (DSCs). Subtle molecular structural variation in the dyes significantly influenced the performance of the DSC devices. By utilizing these dyes in combination with a coba ...

Wiley-VCH Verlag Berlin2014

Thiadiazolo[3,4-c]pyridine Acceptor Based Blue Sensitizers for High Efficiency Dye-Sensitized Solar Cells

Pascal Comte, Michael Graetzel, Shaik Mohammed Zakeeruddin, Carole Graetzel, Robin Humphry-Baker, Joël Teuscher, Thomas Moehl, Chenyi Yi, Jiabao Yang

Two new [1,2,5]thiadiazolo[3,4-c]pyridine-containing D-A-pi-A organic dyes (PT-1 and PT-2) have been designed and synthesized for utilization in dye-sensitized solar cells. PT-2 sensitizer, which was synthesized by incorporating the 4,4-bis(2-ethylhexyl)-4 ...

American Chemical Society2014

Evaluating the critical thickness of TiO2 layer on insulating mesoporous templates for efficient current collection in dye-sensitized solar cells

Pascal Comte, Michael Graetzel, Mohammad Khaja Nazeeruddin, Robin Humphry-Baker, Aravind Kumar Chandiran, Chenyi Yi

In this paper, we present a way of utilizing thin and conformal overlayer of titanium dioxide on insulating mesoporous template as a photoanode for dye-sensitized solar cells (DSC). Different thicknesses of TiO2 ranging from 1 nm to 15 nm are deposited on ...

Wiley-Blackwell2013

Benzo[1,2-b:4,5-b ']difuran-based sensitizers for dye-sensitized solar cells

Michael Graetzel, Chenyi Yi, Hongyu Li

Two BDF-based organic sensitizers, as first examples for their use in dye-sensitized solar cells, are prepared and characterized. They yield promising power conversion efficiencies of up to 5.5% and high open circuit voltages up to 0.82 V. This work demons ...

RSC Publishing2013

Sub-nanometer Ga2O3 tunnelling layer by atomic layer deposition to achieve 1.1V open-circuit potential in dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Robin Humphry-Baker, Nicolas Tétreault, Aravind Kumar Chandiran, Chenyi Yi

Herein, we present the first use of a gallium oxide tunnelling layer to significantly reduce electron recombination in dye-sensitized solar cells (DSC). The sub-nanometer coating is achieved using atomic layer deposition (ALD) and leading to a new DSC reco ...

American Chemical Society2012

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

Avoiding Diffusion Limitations in Cobalt(III/II)-Tris(2,2'-Bipyridine)-Based Dye-Sensitized Solar Cells by Tuning the Mesoporous TiO2 Film Properties

Pascal Comte, Michael Graetzel, Chenyi Yi, Hoi Nok Tsao

Dye-sensitized solar cells based on electrolytes containing cobalt complexes as redox shuttles typically suffer a major limitation in terms of slow diffusion of those couples through the mesoporous TiO2 film. This results in a drop of the photocurrent dens ...

Wiley-Blackwell2012

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

A Spectroscopic and Computational Study of a Photoinduced Cross-Dehydrogenative Coupling Reaction of a Stable Semiquinone Radical

Eric Vauthey, Chenyi Yi, Jakob Grilj

Norrish-type-II reaction on a semiquinone radical: Stable semiquinone radicals serve as novel molecular platforms on which a Norrish-type-II photoreaction can be initiated. A detailed reaction scheme involving a 1,5-hydrogen transfer followed by a cyclizat ...

Wiley-V C H Verlag Gmbh2012

Influence of Donor Groups of Organic D-pi-A Dyes on Open-Circuit Voltage in Solid-State Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Thomas Moehl, Chenyi Yi, Amalie Dualeh, Filippo de Angelis

In solid-state dye-sensitized solar cells (ssDSCs), the poor pore filling of the mesoporous semiconductor and the short diffusion length of charge carriers, in the hole-transport material (HTM) have limited the mesoscopic titania layer to a thickness of 2- ...

American Chemical Society2012

Tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) as p-Type Dopant for Organic Semiconductors and Its Application in Highly Efficient Solid-State Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Julian Burschka, Chenyi Yi, Amalie Dualeh

Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co(III) complexe ...

2011

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