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Ulf Anders Hagfeldt

Cette personne n’est plus à l’EPFL

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Publications associées (296)

Photoinduced Stark Effects and Mechanism of Ion Displacement in Perovskite Solar Cell Materials

Ulf Anders Hagfeldt, Tor Jesper Jacobsson

Organometallic halide perovskites (OMHPs) have recently emerged as a promising class of materials in photovoltaic technology. Here, we present an in-depth investigation of the physics in these systems by measuring the photoinduced absorption (PIA) in OMHPs ...

Amer Chemical Soc2017

Theoretical Treatment of CH3NH3PbI3 Perovskite Solar Cells

Ulf Anders Hagfeldt, Sining Yun, Xiao Zhou

Hybrid halide perovskite solar cells (PSCs) giving over 22% power conversion efficiencies (PCEs) have attracted considerable attention. Although perovskite plays a significant role in the operation of PSCs, the fundamental theories associated with perovski ...

Wiley-Blackwell2017

High efficiency large area perovskite solar cells and process for producing the same

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Chenyi Yi, Xiong Li, Dongqin Bi

The present invention relates to a method for producing a solid state solar cell, comprising the steps of providing a conductive support layer or current collector, applying a metal oxide layer on the conducting support layer, applying at least one sensiti ...

2017

Changes from Bulk to Surface Recombination Mechanisms between Pristine and Cycled Perovskite Solar Cells

Ulf Anders Hagfeldt, Wolfgang Richard Tress, Juan-Pablo Correa-Baena, Silver Hamill Turren Cruz

Several aspects on the photophysical characterization of lead halide hybrid organic inorganic perovskite solar cells remain unsolved. It has been observed that ionic transport and polarization of the interfaces cause very slow changes that interfere with t ...

Amer Chemical Soc2017

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

Nikolaos Vlachopoulos, Ulf Anders Hagfeldt, Liang Wang, Lin Yang, Monica Marcela Lira Cantu, Jiahuan Zhang

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

Photon Energy-Dependent Hysteresis Effects in Lead Halide Perovskite Materials

Ulf Anders Hagfeldt, Tor Jesper Jacobsson, Silver Hamill Turren Cruz

Lead halide perovskites have a range of spectacular properties and interesting phenomena and are a serious candidate for the next generation of photovoltaics with high efficiencies and low fabrication costs. An interesting phenomenon is the anomalous hyste ...

American Chemical Society2017

Analysis of crystalline phases and integration modelling of charge quenching yields in hybrid lead halide perovskite solar cell materials

Ulf Anders Hagfeldt

Organic inorganic metal halide perovskites (OIHPs) has emerged as promising photovoltaic materials the latest years. Many OIHPs, however, have complex material compositions with mixed cation and halide compositions, phase mixtures, as well as beneficial re ...

Elsevier Science Bv2017

Bulk Heterojunction Tandem Photoelectric Cell Based on p-Si and Phthalocyanine

Ulf Anders Hagfeldt

An organic-inorganic (p-Si and phthalocyanine) hybrid tandem heterojunction Ag/p-Si/AlPc:H2Pc/ITO photoelectric cell was fabricated by pressing technology using preliminary vapor deposited heterojunction films of mixed aluminum-phthalocyanine (AlPc) and me ...

Esg2017

Effect of Cs-Incorporated NiOx on the Performance of Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Jiyoun Seo, Hui-Seon Kim, Monica Marcela Lira Cantu, Haibing Xie

The effect of Cs-incorporated NiOx on perovskite solar cells with an inverted structure was investigated, where NiOx and PCBM were used as selective contacts for holes and electrons, respectively. It was found that the generation of an Ni phase in an NiOx ...

Amer Chemical Soc2017

Exploration of the compositional space for mixed lead halogen perovskites for high efficiency solar cells

Michael Graetzel, Kurt Schenk, Ulf Anders Hagfeldt, Michael Saliba, Tor Jesper Jacobsson

Lead halide perovskites have attracted considerable interest as photoabsorbers in PV-applications over the last few years. The most studied perovskite material achieving high photovoltaic performance has been methyl ammonium lead iodide, CH3NH3PbI3. Recent ...

Royal Society of Chemistry2016

Room Temperature as a Goldilocks Environment for CH3NH3PbI3 Perovskite Solar Cells: The Importance of Temperature on Device Performance

Ulf Anders Hagfeldt, Wolfgang Richard Tress, Juan-Pablo Correa-Baena, Tor Jesper Jacobsson

Terrestrial applications of solar cells during day-night cycling as well as operation in winter and summer involve substantial temperature variations, which influence the photophysics as well as the charge separation and transport properties in the various ...

American Chemical Society2016

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

Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Yasemin Saygili, Kazuteru Nonomura, Enrico Polanski, Anna Eriksson, Jiahuan Zhang, Yan Hao

Blue and green dyes as well as NIR-absorbing dyes have attracted great interest because of their excellent ability of absorbing the incident photons in the red and near-infrared range region. A novel blue D-pi-A dye (Dyenamo Blue), based on the diketopyrro ...

2016

Highly efficient and stable planar perovskite solar cells by solution-processed tin oxide

Michael Graetzel, Ulf Anders Hagfeldt, Ludmilla Steier, Konrad Domanski, Wolfgang Richard Tress, Juan-Pablo Correa-Baena, Antonio Abate, Taisuke Matsui, Michael Saliba, Elham Halvani Anaraki

Perovskite solar cells (PSCs) are one of the most promising lab-scale technologies to deliver inexpensive solar electricity. Low-temperature planar PSCs are particularly suited for large-scale manufacturing. Here, we propose a simple, solution-processed te ...

Royal Society of Chemistry2016

Enhancing Efficiency of Perovskite Solar Cells via N-doped Graphene: Crystal Modification and Surface Passivation

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Amita Ummadisingu, Jingshan Luo, Juan-Pablo Correa-Baena, Antonio Abate, Jiyoun Seo, Michael Saliba, Mahboobeh Hadadian

Controlling the morphology and surface passivation in perovskite solar cells is paramount in obtaining optimal opto-electronic properties. This study incorporates N-doped graphene nanosheets in the perovskite layer, which simultaneously induces an improved ...

Wiley2016

Optical analysis of CH3NH3SnxPb1-I-x(3) absorbers: a roadmap for perovskite-on-perovskite tandem solar cells

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

Organic-inorganic perovskite structures in which lead is substituted by tin are exceptional candidates for broadband light absorption. Herein we present a thorough analysis of the optical properties of CH3NH3SnxPb1-xI3 films, providing the field with defin ...

Royal Society of Chemistry2016

High-Efficiency Perovskite Solar Cells Employing a S,N-Heteropentacene-based D-A Hole-Transport Material

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Peng Gao, Amaresh Mishra, Marius Franckevicius, Dongqin Bi

We developed a new donor--acceptor-type hole-transport material (HTMs) incorporating S,N-heteropentacene as -spacer, triarylamine as donor, and dicyanovinylene as acceptor. In addition to appropriate frontier molecular orbital energies, the new HTM showed ...

Wiley-V C H Verlag Gmbh2016

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

A vacuum flash-assisted solution process for high-efficiency large-area perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jean-David Décoppet, Ulf Anders Hagfeldt, Chenyi Yi, Xiong Li, Jingshan Luo, Dongqin Bi

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achi ...

American Association for the Advancement of Science2016

A low-cost spiro[fluorene-9,9 '-xanthene]-based hole transport material for highly efficient solid-state dye-sensitized solar cells and perovskite solar cells

Michael Graetzel, Ulf Anders Hagfeldt, Dongqin Bi, Peng Liu, Ming Cheng

A low-cost spiro[fluorene-9,9'-xanthene] (SFX) based organic hole transport material (HTM) termed X60 was designed and synthesized using a two-step synthetic route. Devices with X60 as HTM showed high power conversion efficiencies (PCEs) amounting to 7.30% ...

Royal Society of Chemistry2016

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