Publications by Chenyi Yi | EPFL Graph Search

Related publications (43)

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

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

Atomically Altered Hematite for Highly Efficient Perovskite Tandem Water-Splitting Devices

Michael Graetzel, Shaik Mohammed Zakeeruddin, Chenyi Yi

Photoelectrochemical (PEC) cells are attractive for storing solar energy in chemical bonds through cleaving of water into oxygen and hydrogen. Although hematite (alpha-Fe2O3) is a promising photoanode material owing to its chemical stability, suitable band ...

Wiley-VCH Verlag Berlin2017

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, Chenyi Yi, Hoi Nok Tsao, Julian Burschka

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

Ligand-Modulated Excess PbI2 Nanosheets for Highly Efficient and Stable Perovskite Solar Cells

Ulf Anders Hagfeldt, Jingshan Luo, Chenyi Yi, Zaiwei Wang

Excess lead iodide (PbI2), as a defect passivation material in perovskite films, contributes to the longer carrier lifetime and reduced halide vacancies for high-efficiency perovskite solar cells. However, the random distribution of excess PbI2 also leads ...

Wiley-V C H Verlag Gmbh2020

High efficiency Porphyrin Sensitized Mesoscopic Solar Cells

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

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

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

Identifying Fundamental Limitations in Halide Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Chenyi Yi

The temperature dependence of the principal photovoltaic parameters of perovskite photovoltaics is studied. The recombination activation energy is in good agreement with the perovskite's bandgap energy, thereby placing an upper bound on the open-circuit vo ...

Wiley-Blackwell2016

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

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

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

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, Mohammad Ibrahim Dar, Jingshan Luo, Chenyi Yi, Xiong Li, Manuel Tschumi

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

Comprehensive control of voltage loss enables 11.7% efficient solid-state dye-sensitized solar cells

Shaik Mohammed Zakeeruddin, Jacques-Edouard Moser, Ulf Anders Hagfeldt, Ladislav Kavan, Jingshan Luo, Chenyi Yi, Yuhang Liu, Yiming Cao, Yasemin Saygili, Heewon Bahng

The relatively large voltage loss (Vloss) in excitonic type solar cells severely limits their power conversion efficiencies (PCEs). Here, we report a comprehensive control of Vloss through efficacious engineering of the sensitizer and redox mediator, makin ...

2018

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, Chenyi Yi, Amalie Dualeh, Julian Burschka

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

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, Thomas Moehl, Chenyi Yi, Arianna Marchioro, 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

Porphyrin-Sensitized Solar Cells with Cobalt (II/III)-Based Redox Electrolyte Exceed 12 Percent Efficiency

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Chenyi Yi, Aswani Yella, Aravind Kumar Chandiran, Hoi Nok Tsao

The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized ...

American Association for the Advancement of Science2011

Photovoltaic Performance of Porphyrin-Based Dye-Sensitized Solar Cells with Binary Ionic Liquid Electrolytes

Michael Graetzel, Shaik Mohammed Zakeeruddin, Chenyi Yi, Jean-David Décoppet

Herein, green porphyrin sensitizer Y350-based dye-sensitized solar cells (DSCs) with binary ionic liquid-based electrolytes are studied, which are a mixture of 1-methyl-3-propyl-imidazolium iodide and 1-methyl-1-butylpyrrolidinium bis(trifluromethylsulfony ...

2020

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

Michael Graetzel, Chenyi Yi, Michele Cascella, 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

A vacuum flash-assisted solution process for high-efficiency large-area perovskite solar cells

Michael Graetzel, Ulf Anders Hagfeldt, Shaik Mohammed Zakeeruddin, Jingshan Luo, Chenyi Yi, Dongqin Bi, Xiong Li, Jean-David Décoppet

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achi ...

American Association for the Advancement of Science2016

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

Michael Graetzel, Chenyi Yi

Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A) and a hybrid electron donor (D) of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were synthesized and characterized. Both of ...

Beilstein-Institut2015

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

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

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

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

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

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

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

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