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Ulf Anders Hagfeldt

Cette personne n’est plus à l’EPFL

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Publications associées (296)

Improving efficiency and stability of perovskite solar cells with photocurable fluoropolymers

Michael Graetzel, Ulf Anders Hagfeldt, Juan-Pablo Correa-Baena

Organometal halide perovskite solar cells have demonstrated high conversion efficiency but poor long-term stability against ultraviolet irradiation and water. We show that rapid light-induced free-radical polymerization at ambient temperature produces mult ...

American Association for the Advancement of Science2016

The Role of 3D Molecular Structural Control in New Hole Transport Materials Outperforming Spiro-OMeTAD in Perovskite Solar Cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Lin Yang, Peng Liu, Jiahuan Zhang

Wiley-VCH Verlag Berlin2016

Facile synthesized organic hole transporting material for perovskite solar cell with efficiency of 19.8%

Michael Graetzel, Ulf Anders Hagfeldt, Peng Gao, Dongqin Bi

The exploration of alternative molecular hole-transporting materials (HTMs) specifically for high performance perovskite solar cells (PSCs) is a relatively recent research area. Aiming for further increasing the 'efficiency-cost ratio' of PSCs, we develope ...

Elsevier Science Bv2016

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

Development of high efficiency 100% aqueous cobalt electrolyte dye-sensitised solar cells

Ulf Anders Hagfeldt

In this study we report the application of three cobalt redox shuttles in 100% aqueous electrolyte dyesensitised solar cells (DSCs). By using chloride as a counter-ion for cobalt bipyridine, cobalt phenanthroline and cobalt bipyridine pyrazole, the redox s ...

Royal Soc Chemistry2016

Mesoporous SnO2 electron selective contact enables UV-stable perovskite solar cells

Michael Graetzel, Ulf Anders Hagfeldt, Juan-Pablo Correa-Baena, Antonio Abate

Perovskite solar cells are a promising new technology for large scale energy applications. The current major challenge for commercialization is increasing the device lifetime under real working conditions. State-of-the-art perovskite solar cells are prepar ...

Elsevier Science Bv2016

Unreacted PbI2 as a Double-Edged Sword for Enhancing the Performance of Perovskite Solar Cells

Jacques-Edouard Moser, Joël Teuscher, Kurt Schenk, Ulf Anders Hagfeldt, Marine Eva Fedora Bouduban, Wolfgang Richard Tress, Juan-Pablo Correa-Baena, Tor Jesper Jacobsson, Elham Halvani Anaraki

Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that not only the composition but also the precise stoichiometr ...

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

High-Performance Perovskite Solar Cells with Enhanced Environmental Stability Based on Amphiphile-Modified CH3NH3PbI3

Mohammad Khaja Nazeeruddin, Rosario Scopelliti, Ulf Anders Hagfeldt, Emad Oveisi, Peng Gao, Jingshan Luo, Dongqin Bi

A new aliphatic fluorinated amphiphilic additive is added to CH3NH3PbI3 perovskite to tune the morphology and enhance the environmental stability without sacrificing the performance of the devices. Judicious screening of the perovskite precursor solution r ...

Wiley-V C H Verlag Gmbh2016

Efficient solid-state dye sensitized solar cells: The influence of dye molecular structures for the in-situ photoelectrochemically polymerized PEDOT as hole transporting material

Mohammad Khaja Nazeeruddin, Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Jiahuan Zhang

Solid-state dye sensitized solar cells (sDSCs) with organic small molecule hole transporting materials (HTMs) have limited efficiencies due to the incomplete pore filling of the HTMs in the thick mesoporous electrodes and the low hole conductivity of HTMs. ...

Elsevier Science Bv2016

The effect of mesoporous TiO2 pore size on the performance of solid-state dye sensitized solar cells based on photoelectrochemically polymerized Poly(3,4-ethylenedioxythiophene) hole conductor

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Jiahuan Zhang

Photoelectrochemical polymerization of poly(3,4-ethylenedioxythiphene) (PEDOT) has recently been introduced and widely investigated for fabrication of the hole transporting material (HTM) in highly efficient solid state dye sensitized solar cells (sDSCs). ...

Pergamon-Elsevier Science Ltd2016

A study of oligothiophene-acceptor dyes in p-type dye-sensitized solar cells

Ulf Anders Hagfeldt, Peng Liu, Lei Zhang

Two new dyes, E1 and E2, equipped with triphenylamine as the electron donor, oligothiophene as the linker and different electron acceptor groups, have been designed and synthesized as photosensitizers for p-type dye-sensitized solar cells (p-DSCs). A syste ...

Royal Soc Chemistry2016

Geometrical and energetical structural changes in organic dyes for dye-sensitized solar cells probed using photoelectron spectroscopy and DFT

Ulf Anders Hagfeldt, Anna Eriksson

The effects of alkoxy chain length in triarylamine based donor acceptor organic dyes are investigated with respect to the electronic and molecular surface structures on the performance of solar cells and the electron lifetime. The dyes were investigated wh ...

Royal Soc Chemistry2016

Proof-of-concept for facile perovskite solar cell recycling

Ulf Anders Hagfeldt, Norman Pellet, Fabrizio Giordano, Joachim Maier, Jeannette Medina Kadro, Othmar Müntener

Perovskite solar cells based on CH3NH3PbI3 and related materials have reached impressive efficiencies that, on a lab scale, can compete with established solar cell technologies, at least in short-term observations. Despite frequently voiced concerns about ...

Royal Soc Chemistry2016

Ionic Liquid Control Crystal Growth to Enhance Planar Perovskite Solar Cells Efficiency

Michael Graetzel, Shaik Mohammed Zakeeruddin, Kurt Schenk, Ulf Anders Hagfeldt, Amita Ummadisingu, Konrad Domanski, Fabrizio Giordano, Jingshan Luo, Juan-Pablo Correa-Baena, Antonio Abate, Jiyoun Seo, Taisuke Matsui, Michael Saliba, Mahboobeh Hadadian

Ionic liquids can retard the perovskite crystallization with the aim to form compact films with larger and more uniformly distributed grain size. The ionic liquid driven crystallization is exploited to prepared a record planar perovskite solar cell with st ...

Wiley-VCH Verlag Berlin2016

Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Amita Ummadisingu, Konrad Domanski, Wolfgang Richard Tress, Juan-Pablo Correa-Baena, Antonio Abate, Jiyoun Seo, Taisuke Matsui, Michael Saliba

All of the cations currently used in perovskite solar cells abide by the tolerance factor for incorporation into the lattice. We show that the small and oxidation-stable rubidium cation (Rb+) can be embedded into a "cation cascade" to create perovskite mat ...

American Association for the Advancement of Science2016

Constructive Effects of Alkyl Chains: A Strategy to Design Simple and Non-Spiro Hole Transporting Materials for High-Efficiency Mixed-Ion Perovskite Solar Cells

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Juan-Pablo Correa-Baena, Peng Liu, Mahboobeh Hadadian, Jiahuan Zhang

Wiley-V C H Verlag Gmbh2016

Strategy to Boost the Efficiency of Mixed-Ion Perovskite Solar Cells: Changing Geometry of the Hole Transporting Material

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Jiahuan Zhang

The hole transporting material (HTM) is an essential component in perovskite solar cells (PSCs) for efficient extraction and collection of the photoinduced charges. Triphenylamine- and carbazole-based derivatives have extensively been explored as alternati ...

Amer Chemical Soc2016

Ambient air-processed mixed-ion perovskites for high-efficiency solar cells

Ulf Anders Hagfeldt, Juan-Pablo Correa-Baena, Jiahuan Zhang

Mixed-ion (FAPbI(3))(1-x)(MAPbBr(3))(x) perovskite solar cells have achieved power conversion efficiencies surpassing 20%. However, in order to obtain these high efficiencies the preparation is performed in a controlled inert atmosphere. Here, we report a ...

Royal Society of Chemistry2016

A New 1,3,4-Oxadiazole-Based Hole-Transport Material for Efficient CH3NH3PbBr3 Perovskite Solar Cells

Michael Graetzel, Ulf Anders Hagfeldt, Juan-Pablo Correa-Baena, Antonio Abate

A new hole-transport material (HTM) based on the 1,3,4-oxadiazole moiety (H1) was prepared through a single-step synthetic pathway starting from commercially available products. Thanks to a deep HOMO level, H1 was used as HTM in CH3NH3PbBr3 perovskite sola ...

Wiley-V C H Verlag Gmbh2016

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