Publications by Nikolaos Vlachopoulos

Cuprous oxide-Shewanella mediated photolytic hydrogen evolution

Christos Comninellis, Michael Graetzel, Nikolaos Vlachopoulos, Kevin Sivula, Linfeng Pan, Meng Xia, Michele Morgante

However, its green production process is expensive, involving water electrolysis, which requires a significant amount of energy. New technologies have been developed to decrease the cost associated with water electrolysis, such as using microbial electroly ...

2025

Hydroxamic acid pre-adsorption raises the efficiency of cosensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Yiming Cao, Felix Thomas Eickemeyer, Yameng Ren, Dan Zhang, Jiajia Suo

Dye-sensitized solar cells (DSCs) convert light into electricity by using photosensitizers adsorbed on the surface of nanocrystalline mesoporous titanium dioxide (TiO2) films along with electrolytes or solid charge-transport materials(1-3). They possess ma ...

NATURE PORTFOLIO2023

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, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Brian Irving Carlsen, Bowen Yang, 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

Experimental and theoretical study of organic sensitizers for solid-state dye-sensitized solar cells (s-DSSCs)

Nikolaos Vlachopoulos

The effect of a series of triarylamine based D-pi-A organic dyes, namely RK1, BA504, BA741 and the simple L1 reference dye on solid-state dye sensitized solar cells (s-DSSCs) performances was studied. The solid hole transporting material (HTM) was obtained ...

ELSEVIER SCIENCE SA2022

New approaches in component design for dye-sensitized solar cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt

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

Microbial bioelectrochemical cells for hydrogen generation based on irradiated semiconductor photoelectrodes

Nikolaos Vlachopoulos, Fabian Fischer, Ulf Anders Hagfeldt, Michele Morgante

In recent years, one of the most important challenges of the 21st century is to satisfy the ever-increasing world's energy demand. Many efforts are being undertaken to find alternative renewable energy sources, which ideally should outcompete fossil fuel u ...

IOP PUBLISHING LTD2021

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

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

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

Rapid hybrid perovskite film crystallization from solution

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

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

A molecular photosensitizer achieves a Voc of 1.24 V enabling highly efficient and stable dye-sensitized solar cells with copper(II/I)-based electrolyte

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Yiming Cao, Marko Stojanovic, Etienne Christophe Socie, Felix Thomas Eickemeyer, Yameng Ren, Dan Zhang

To develop photosensitizers with high open-circuit photovoltage (Voc) is a crucial strategy to enhance the power conversion efficiency (PCE) of co-sensitized solar cells. Here, we show a judiciously tailored organic photosensitizer, coded MS5, featuring th ...

Nature Research2021

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

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

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

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

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

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, 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

Dye sensitized photoelectrolysis cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Sining Yun

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

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

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

Diverging surface reactions at TiO2- or ZnO-based photoanodes in dye-sensitized solar cells

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

Fast recombination of electrons from semiconductors with the oxidized redox species in the electrolyte represents a major bottleneck in the improvement of ZnO-based dye-sensitized solar cells (DSSCs). While processes at the semiconductor-electrolyte interf ...

ROYAL SOC CHEMISTRY2019

Electrochemically polymerized poly (3, 4-phenylenedioxythiophene) as efficient and transparent counter electrode for dye sensitized solar cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Lin Yang, Jiahuan Zhang, Yan Hao

A new conducting polymer poly (3, 4-phenylenedioxythiophene) is synthesized by the electrochemical polymerization technique with different solvents. We find that solvents used in electrochemical polymerization play important roles for the catalytic activit ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Photoelectrochemical Cells Based on Dye Sensitization for Electricity and Fuel Production

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt

Dye-sensitized semiconductor oxide photoelectrodes in which light is absorbed by a monomolecular layer of dye chemisorbed on a porous oxide substrate have attracted considerable interest in the last 35 years, mainly for the conversion of sunlight to electr ...

SWISS CHEMICAL SOC2019

Directly Photoexcited Oxides for Photoelectrochemical Water Splitting

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Linfeng Pan

Artificial photosynthesis promises to become a sustainable way to harvest solar energy and store it in chemical fuels by means of photoelectrochemical (PEC) cells. Although it is intriguing to shift the fossil-fuel-based economy to a renewable carbon-neutr ...

WILEY-V C H VERLAG GMBH2019

Toward an alternative approach for the preparation of low-temperature titanium dioxide blocking underlayers for perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Kazuteru Nonomura, Lichen Zhao, Su Htike Aung

The anodic electrodeposition method is investigated as an alternative technique for the preparation of a titanium oxide (TiO2) blocking underlayer (UL) for perovskite solar cells (PSCs). Extremely thin Ti-IV-based films are grown from aqueous acidic titani ...

Royal Society of Chemistry2019

Metal Coordination Complexes as Redox Mediators in Regenerative Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Marko Stojanovic, Yasemin Saygili, Natalie Flores Diaz

Dye-sensitized solar cells (DSSCs) have attracted a substantial interest in the last 30 years for the conversion of solar power to electricity. An important component is the redox mediator effecting the transport of charge between the photoelectrode and th ...

2019