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Nikolaos Vlachopoulos

Cette personne a quitté l’EPFL

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Publications associées (44)

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Rapid hybrid perovskite film crystallization from solution

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Lukas Pfeifer, Sandy Sanchez Alonso

The use of a solution process to grow perovskite thin films allows to extend the material processability. It is known that the physicochemical properties of the perovskite material can be tuned by altering the solution precursors as well as by controlling ...

Royal Society of Chemistry2021

Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of Poly(3,4-ethylenedioxythiophene) in Solid-State Dye-Sensitized Solar Cells: Comparison of In Situ Photoelectrochemical Polymerization in Aqueous Micellar and Organic Media

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Lin Yang

Solid-state dye-sensitized solar cells (sDSCs) are devoid of such issues as electrolyte evaporation or leakage and electrode corrosion, which are typical for traditional liquid electrolyte-based DSCs. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the ...

American Chemical Society2015

Photoinduced electron transfer and redox-type photochromism of a TiO2-anchored molecular diad

Michael Graetzel, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Jacques-Edouard Moser, Péter Kalman Péchy, Nikolaos Vlachopoulos

Royal Society of Chemistry1996

Blocking the Charge Recombination with Diiodide Radicals by TiO2 Compact Layer in Dye-Sensitized Solar Cells

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Kazuteru Nonomura

The addition of a compact titanium dioxide (TiO2) layer between the fluorine-doped tin oxide (FTO) coated glass substrate and the mesoporous TiO2 layer in the dye-sensitized solar cell (DSC) based on the iodide/triiodide redox couple (I-/I-3(-)) is known t ...

ELECTROCHEMICAL SOC INC2019

Photovoltaic performance and stability of nanocrystalline injection solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Péter Kalman Péchy, Pascal Comte, Nikolaos Vlachopoulos, Paul Liska

1997

Efficient dye regeneration at low driving force achieved in triphenylamine dye LEG4 and TEMPO redox mediator based dye-sensitized solar cells

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos

Minimizing the driving force required for the regeneration of oxidized dyes using redox mediators in an electrolyte is essential to further improve the open-circuit voltage and efficiency of dye-sensitized solar cells (DSSCs). Appropriate combinations of r ...

Royal Society of Chemistry2015

Perovskite solar cell - electrochemical double layer capacitor interplay

Michael Graetzel, Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Michael Saliba, Juan-Pablo Correa-Baena

We demonstrate that by a proper design of a system comprising a perovskite solar cell (PSC) coupled to an electrochemical double-layer capacitor (EDLC), it is possible to simultaneously improve both the PSC and EDLC performance and outperform each single u ...

Elsevier2017

New approaches in component design for dye-sensitized solar cells

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos

The present perspective presents a number of issues related to the current direction of DSSC research, with emphasis on the transition from iodide-containing electrolyte to charge-transport media (CTMs), electrolytes or solid-state conductors based on inor ...

ROYAL SOC CHEMISTRY2021

The Rise of Dye-Sensitized Solar Cells: From Molecular Photovoltaics to Emerging Solid-State Photovoltaic Technologies

Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Yuhang Liu, Lukas Pfeifer, Jovana Milic, Yameng Ren, Marko Stojanovic, Natalie Flores Diaz, Zhongjin Shen

Over the past three decades, dye-sensitized solar cells (i. e. Gratzel cells) have evolved from a pioneering concept of molecular photovoltaics to large-scale industrial deployment. In this review article, we provide a historical overview of the developmen ...

WILEY-V C H VERLAG GMBH2021

Molecularly Engineered Low-Cost Organic Hole-Transporting Materials for Perovskite Solar Cells: The Substituent Effect on Non-fused Three-Dimensional Systems

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Bowen Yang, Brian Irving Carlsen, Jiajia Suo

In this work, we describe a new class of non-fused 3D asymmetric compounds (named 1, 2, 3, and 4) as low-cost organic hole-transporting materials (HTMs) for perovskite solar cells (PSCs). The fundamental understanding of the influence of the methylthio and ...

AMER CHEMICAL SOC2022

Additives, Hole Transporting Materials and Spectroscopic Methods to Characterize the Properties of Perovskite Films

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Michael Saliba, Nikolaos Vlachopoulos, Jiyoun Seo, Amita Ummadisingu, Marko Stojanovic

The achievement of high efficiency and high stability in perovskite solar cells (PSCs) requires optimal selection and evaluation of the various components. After a brief introduction to the perovskite materials and their historical evolution, the first par ...

Schweizerische Chemische Gesellschaft2017

Dye sensitized photoelectrolysis cells

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos

To advance the progress of photoelectrolysis, various promising devices integrated with p- and n-type photocatalysts and dye sensitized photoelectrodes have been systematically studied. This review discusses, from theory to practice, an integration strateg ...

Royal Society of Chemistry2019

Incorporation of Counter Ions in Organic Molecules: New Strategy in Developing Dopant-Free Hole Transport Materials for Efficient Mixed-Ion Perovskite Solar Cells

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Lin Yang

Hole transport matertial (HTM) as charge selective layer in perovskite solar cells (PSCs) plays an important role in achieving high power conversion efficiency (PCE). It is known that the dopants and additives are necessary in the HTM in order to improve t ...

Wiley-V C H Verlag Gmbh2017

Effect of TiO2 Photoanodes Morphology and Dye Structure on Dye-Regeneration Kinetics Investigated by Scanning Electrochemical Microscopy

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Kazuteru Nonomura, Gunther Wittstock

The dye regeneration in dye-sensitized solar cells (DSSCs) is improved by optimizing the charge separation at the level of the sensitized semiconductor treatment of the mesoporous electrode by TiCl4 that passivates the surface for back electron transfer re ...

2020

Studies on the Interfacial Electric Field and Stark Effect at the TiO2/Dye/Electrolyte Interface

Nikolaos Vlachopoulos

Interfaces of dye-sensitized TiO2 nanoparticles with electrolytes or hole conductors have been widely applied in photoelectrochemical cells. However, the fundamental understanding of their properties and function is still poor. Herein, we demonstrate that ...

American Chemical Society2016

Long-Lived Photoinduced Charge Separation and Redox-Type Photochromism on Mesoporous Oxide Films Sensitized by Molecular Dyads

Michael Graetzel, Shaik Mohammed Zakeeruddin, Robin Humphry-Baker, Jacques-Edouard Moser, Nikolaos Vlachopoulos

1999

A tandem redox system with a cobalt complex and 2-azaadamantane-N-oxyl for fast dye regeneration and open circuit voltages exceeding 1 V

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Jacques-Edouard Moser, Nikolaos Vlachopoulos, Natalie Flores Diaz, Heewon Bahng

A new tandem electrolyte composed of two redox pairs, the organic radical 2-azaadamantane-N-oxyl (AZ) and the well-known redox pair Co(bpy)(3) was investigated in dye sensitized solar cells. Importantly, an increase in V-OC was achieved using the ...

Royal Society of Chemistry2019

Efficient Blue-Colored Solid-State Dye-Sensitized Solar Cells: Enhanced Charge Collection by Using an in Situ Photoelectrochemically Generated Conducting Polymer Hole Conductor

Michael Graetzel, Ulf Anders Hagfeldt, Nikolaos Vlachopoulos, Thomas Wesley Holcombe

A high power conversion efficiency (PCE) of 5.5% was achieved by efficiently incorporating a diketopyrrolopyrrole-based dye with a conducting polymer poly(3,4-ethylenediothiophene) (PEDOT) hole-transporting material (HTM) that was formed in situ, compared ...

Wiley-V C H Verlag Gmbh2016

Solid-state dye-sensitized solar cells using polymeric hole conductors

Michael Graetzel, Nikolaos Vlachopoulos

The present review presents the application of electronically conducting polymers (conducting polymers) as hole conductors in solid-state dye solar cells (S-DSSCs). At first, the basic principles of dye solar cell operation are presented. The next section ...

ROYAL SOC CHEMISTRY2021

Carbon nanotube film replacing silver in high-efficiency solid-state dye solar cells employing polymer hole conductor

Ulf Anders Hagfeldt, Nikolaos Vlachopoulos

A semitransparent, flexible single-walled carbon nanotube (SWCNT) film was efficiently used in place of evaporated silver as the counter electrode of a poly(3,4-ethylenedioxythiophene) polymer-based solid-state dye solar cell (SSDSC): the solar-to-electric ...

Springer Verlag2015