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Ladislav Kavan

Cette personne a quitté l’EPFL

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Publications associées (45)

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Nanocrystalline Boron-Doped Diamond as a Corrosion-Resistant Anode for Water Oxidation via Si Photoelectrodes

Kevin Sivula, Jun Ho Yum, Ladislav Kavan, Florian Le Formal

Due to its high sensitivity to corrosion, the use of Si in direct photoelectrochemical (PEC) water-splitting systems that convert solar energy into chemical fuels has been greatly limited. Therefore, the development of low-cost materials resistant to corro ...

AMER CHEMICAL SOC2018

Electrochemical Properties of Cu(II/I)-Based Redox Mediators for Dye-Sensitized Solar Cells

Michael Graetzel, Ulf Anders Hagfeldt, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Yasemin Saygili, Marina Freitag

Three Cu(II/I)-phenanthroline and Cu(II/I)-bipyridine redox mediators are studied on various electrodes and in variety of electrolyte solutions using cyclic voltammetry and impedance spectroscopy on symmetrical dummy cells. Graphene-based catalysts provide ...

2017

Multi-walled carbon nanotubes functionalized by carboxylic groups: Activation of TiO2 (anatase) and phosphate olivines (LiMnPO4; LiFePO4) for electrochemical Li-storage

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Florian Le Formal

Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO2 (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO2 is improved by nanotube networking, but the Li-st ...

Elsevier2010

Organized Mesoporous TiO2 Films Stabilized by Phosphorus: Application for Dye-Sensitized Solar Cells

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

A synthetic protocol was developed for the preparation of thin mesoporous TiO2 films with enhanced thermal stability. This objective was achieved by a modification of the procedure of supramolecular templating by a Pluronic P-123 copolymer by an addition o ...

2010

Ultrathin Buffer Layers of SnO2 by Atomic Layer Deposition: Perfect Blocking Function and Thermal Stability

Michael Graetzel, Ladislav Kavan, Ludmilla Steier

This study pinpoints the advantages of ultrathin electron 15 selective layers (ESL) of SnO2 fabricated by atomic layer deposition (ALD). These layers recently caught attention in planar perovskite solar cells and appear as powerful alternatives to other ox ...

American Chemical Society2017

Graphene-based cathodes for liquid-junction dye sensitized solar cells: Electrocatalytic and mass transport effects

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

The optimization of mediator/cathode in a dye sensitized solar cell (DSC) requires detailed knowledge about their electrochemical properties. Particularly, the kinetics of mediator's turnover on the cathode and the mass transport of mediator in the electro ...

Pergamon-Elsevier Science Ltd2014

Molecular wiring of LiMnPO4 (olivine) by ruthenium(II)-bipyridine complexes

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan

LiMnPO4 (olivine) was surface-modified by two different complexes: Ru-bis(4,4'-diethoxycarbonyl-2,2'-bipyridine)(4,4'-dicarboxylate-2,2'-bipyridine) and Ru-bis(4-carboxylic acid-4'-carboxylate-2,2'-bipyridine)(4,4'-dinonyl-2,2'bipyridine). These complexes ...

Elsevier2009

Copper Bipyridyl Redox Mediators for Dye-Sensitized Solar Cells with High Photovoltage

Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Jacques-Edouard Moser, Ladislav Kavan, Nikolaos Vlachopoulos, Fabrizio Giordano, Norman Pellet, Yiming Cao, Yasemin Saygili, Marina Freitag

Redox mediators play a major role determining the photocurrent and the photovoltage in dye-sensitized solar cells (DSCs). To maintain the photocurrent, the reduction of oxidized dye by the redox mediator should be significantly faster than the electron bac ...

American Chemical Society2016

Effect of imidazole-based additives on the voltage of dye sensitized solar cells with Cu(II/I) redox mediators

Michael Graetzel, Ladislav Kavan

Acetonitrile solutions of Cu(tmby)22+ exhibit aging-dependent changes of UV–Vis spectra, which were attributed to partial reduction to Cu(tmby)2+. This effect is boosted by the addition of imidazole bases, i.e., N-methyl-benzimidazole (NMB) or 5‑chloro-1-e ...

2025

Novel highly active Pt/graphene catalyst for cathodes of Cu(II/I)-mediated dye-sensitized solar cells

Michael Graetzel, Ulf Anders Hagfeldt, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Yasemin Saygili, Marina Freitag

Novel highly active, optically-transparent electrode catalyst containing Pt, PtOx, graphene oxide and stacked graphene platelet nanofibers is developed for a cathode of Cu(II/I)-mediated dye-sensitized solar cells. The catalyst layer is deposited on a FTO ...

Pergamon-Elsevier Science Ltd2017

Electrochemical Properties of the Supramolecular Assembly of Ruthenium(II)-bipyridine Complex with Single-Walled Carbon Nanotubes

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan

The supramolecular assembly of Ru-bipyridine complex, coded Z-907Na, with single-walled carbon nanotube (SWNT) exhibits unique redox behavior, which is applicable for the nanotube wiring of LiFePO4 (olivine). Cyclic voltammograms of thin films of Z-907Na/S ...

Electrochemical Society2009

Optically Transparent Cathode for Co(III/II) Mediated Dye-Sensitized Solar Cells Based on Graphene Oxide

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

Thin semitransparent films were fabricated on F-doped SnO2 (FTO) from single-layer graphene oxide (GO) either pure or in a composite with graphene nanoplatelets. Electrocatalytic activity of prepared films was tested for the Co(bpy)(3)(3+/2+) redox couple ...

Amer Chemical Soc2012

Graphene Nanoplatelets Outperforming Platinum as the Electrocatalyst in Co-Bipyridine-Mediated Dye-Sensitized Solar Cells

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

Graphene nanoplatelets (GNP) in the form of thin semitransparent films on F-doped SnO2 (FTO) exhibit high electrocatalytic activity for the Co(bpy)(3)(3+/2+) redox couple in acetonitrile electrolyte solution. The GNP film is superior to the traditional ele ...

American Chemical Society2011

Electrolyte effects and stability of Zn/Li dual-ion batteries with water-in-salt electrolytes

Nikolaos Kakavas, Michael Graetzel, Ladislav Kavan, Felix Thomas Eickemeyer, Jiaqi Xu, Wenzhe Niu

Aqueous zinc-ion batteries have emerged as promising candidates for safe and cost-effective energy storage, yet their performance remains constrained by electrode stability and electrolyte composition. In this study, we investigate the electrochemical beha ...

2025

Application of graphene-based nanostructures in dye-sensitized solar cells

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

The paper reviews recent advances in the application of graphene and related materials, viz. graphene nanoplatelets (GNP), functionalized graphene sheets (FGS), graphene oxide (GO), and reduced graphene oxide (rGO) as electrode building materials in dye-se ...

Wiley-Blackwell2013

Electron-Selective Layers for Dye-Sensitized Solar Cells Based on TiO2 and SnO2

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan

Titanium dioxide (anatase, rutile) and quasi-amorphous tin dioxide are prepared on F-doped SnO2 in the form of dense thin films, which can serve as electron-selective layers in perovskite solar cells and dye-sensitized solar cells (DSSCs). The present stud ...

2020

Graphene Nanoplatelet Cathode for Co(III)/(II) Mediated Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Ladislav Kavan

Graphene nanoplatelets (GNP) in the form of thin semitransparent film on F-doped SnO2 (FTO) exhibit high electrocatalytic activity for Co(L)(2); where L is 6-(1H-pyrazol-1-yl)-2,2'-bipyridine. The exchange current densities for the Co(2+/)3(+)(L)(2) redox ...

American Chemical Society2011

Low-temperature Fabrication of Highly-Efficient, Optically-Transparent (FTO-free) Graphene Cathode for Co-Mediated Dye-Sensitized Solar Cells with Acetonitrile-free Electrolyte Solution

Michael Graetzel, Shaik Mohammed Zakeeruddin, Paul Liska, Ladislav Kavan

Propionitrile electrolyte solutions mixed with sulfolane or with 1-ethyl 3-methyl imidazolium tetracyanoborate (ionic liquid) are optimized for Co(bpy)(3)(3+)/Co(bpy)(3)(2+)-tmediated DSCs working at low illumination intensity. Highly-active cathode cataly ...

Elsevier2016

Electrochemical Characterization of TiO2 Blocking Layers for Dye-Sensitized Solar Cells

Michael Graetzel, Ladislav Kavan, Thomas Moehl, Nicolas Tétreault

Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from the substrat ...

American Chemical Society2014

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