Publications by Marina Freitag

Molecular engineering of low-cost, efficient, and stable photosensitizers for dye-sensitized solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Marina Freitag, Jing Gao, Felix Thomas Eickemeyer, Zhongjin Shen, Lukas Pfeifer

The cost, stability, and photovoltaic performance of photosensi-tizers play a key role in the commercialization of dye-sensitized solar cells (DSCs). Herein, three novel sensitizers termed ZS10, ZS11, and ZS12 are described based on the simple chemical str ...

Cell Press2023

Liquid State and Zombie Dye Sensitized Solar Cells with Copper Bipyridine Complexes Functionalized with Alkoxy Groups

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Joël Teuscher, Rosario Scopelliti, Ulf Anders Hagfeldt, Marko Stojanovic, Yasemin Saygili, Marina Freitag, Hui-Seon Kim

Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolytes or as solid state hole transport materials (HTMs). The solid state devices that employ copper complex HTMs can be simply obtained by solvent evaporation ...

2020

Effect of Coordination Sphere Geometry of Copper Redox Mediators on Regeneration and Recombination Behavior in Dye-Sensitized Solar Cell Applications

Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Joël Teuscher, Ulf Anders Hagfeldt, Marko Stojanovic, Fabrizio Giordano, Yasemin Saygili, Marina Freitag, Jan Tiepelt

The recombination of injected electrons with oxidized redox species and regeneration behavior of copper redox mediators are investigated for four copper complexes, [Cu(dmby)2]2+/1+ (dmby = 6,6′-dimethyl-2,2′- bipyridine), [Cu(tmby)2]2+/1+ (tmby = 4,4′,6,6′ ...

2018

Redox melts formed by copper (i)/(ii) complexes as charge transfer and charge storage materials

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Yiming Cao, Marko Stojanovic, Marina Freitag

The present invention relates to a redox copper complex melt comprising a metalorganic complex of formula (I) [Cu (La) n ] (I), wherein n is an integer 2; and La is a bidentate ligand selected from a ligand according to any one of formulae (1) and (2): ...

2018

Planar Perovskite Solar Cells with High Open-Circuit Voltage Containing a Supramolecular Iron Complex as Hole Transport Material Dopant

Shaik Mohammed Zakeeruddin, Wolfgang Richard Tress, Yasemin Saygili, Juan-Pablo Correa-Baena, Michael Saliba, Marina Freitag, Bartholomeus Wilhelmus Henricus Saes, Silver Hamill Turren Cruz

2018

Dye-sensitized solar cells for efficient power generation under ambient lighting

Paul Liska, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Joël Teuscher, Ulf Anders Hagfeldt, Fabrizio Giordano, Yasemin Saygili, Xiaoyu Zhang, Marina Freitag

Solar cells that operate efficiently under indoor lighting are of great practical interest as they can serve as electric power sources for portable electronics and devices for wireless sensor networks or the Internet of Things. Here, we demonstrate a dye-s ...

Nature Publishing Group2017

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

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Ulf Anders Hagfeldt, 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

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

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ladislav Kavan, Ulf Anders Hagfeldt, 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

11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials

Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Joël Teuscher, Ulf Anders Hagfeldt, Norman Pellet, Yiming Cao, Amita Ummadisingu, Fabrizio Giordano, Jingshan Luo, Yasemin Saygili, Marina Freitag

Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO2 scaffolds, leading to low performances. Here we rep ...

Nature Publishing Group2017

Copper Phenanthroline as a Fast and High-Performance Redox Mediator for Dye-Sensitized Solar Cells

Michael Graetzel, Ulf Anders Hagfeldt, Fabrizio Giordano, Marina Freitag, Yan Hao

The most commonly used redox mediators in dye-sensitized solar cells (DSCs), iodide/triiodide and cobalt trisbipyridine (Co(bpy)(3)), were successfully replaced by bis (2,9-dimethy1-1,10-phenanthroline) copp er (I/H) (Cu(dmp)(2)). The use ...

American Chemical Society2016

Cobalt and/or copper complexes for use as hole transport layer dopants to improve optoelectronic or photoelectrochemical devices

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Julian Burschka, Fabrizio Giordano, Marina Freitag

This invention discloses a new class of dopants that allows easy tuning of the chem., phys., optical and/or electronic properties of the doping agent in order to carefully adapt it to the desired application, such as org. solar cells or solid state dye-sen ...

2016

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

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

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

Supramolecular Hemicage Cobalt Mediators for Dye-Sensitized Solar Cells

Ulf Anders Hagfeldt, Marina Freitag

A new class of dye-sensitized solar cells (DSSCs) using the hemicage cobalt-based mediator Co(ttb) with the highly preorganized hexadentate ligand 5,5 '', 5 ''''-((2,4,6-triethyl benzene-1,3,5-triyl)tris(ethane-2,1-diyl))tri-2,2'-bipyridine (ttb) ...

Wiley-Blackwell2016