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Ulf Anders Hagfeldt

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Publications associées (296)

The application of transition metal complexes in hole-transporting layers for perovskite solar cells: Recent progress and future perspectives

Ulf Anders Hagfeldt

In the past few years, the photovoltaic community has witnessed a fast growth of inorganic-organic hybrid perovskite solar cells (PSCs) due to their exceptional power conversion efficiencies with a certified record value exceeding 25%, which rivals the est ...

ELSEVIER SCIENCE SA2020

Dopant-Free Hole-Transport Materials with Germanium Compounds Bearing Pseudohalide and Chalcogenide Moieties for Perovskite Solar Cells

Ulf Anders Hagfeldt, Natalie Flores Diaz

Hole-transport materials (HTMs) are key electronic components for the functioning of perovskite solar cells (PSCs) as they extract the photogenerated holes from the perovskite to be transported subsequently to the back electrode while minimizing the loss f ...

AMER CHEMICAL SOC2020

Highly efficient, stable and hysteresis-less planar perovskite solar cell based on chemical bath treated Zn2SnO4 electron transport layer

Michael Graetzel, Ulf Anders Hagfeldt, Wolfgang Richard Tress, Zaiwei Wang, Mohammad Mahdi Tavakoli, Seckin Akin, Faranak Sadegh, Marco Alejandro Ruiz Preciado

The electron transport layer (ETL) is a key constituent in perovskite solar cells (PSCs). It should provide efficient and selective electron extraction, low resistivity and high stability. Here, zinc stannate (Zn2SnO4, ZSO) is employed as an ETL in planar ...

Elsevier2020

Zinc Phthalocyanine Conjugated Dimers as Efficient Dopant-Free Hole Transporting Materials in Perovskite Solar Cells

Ulf Anders Hagfeldt, Kazuteru Nonomura, Natalie Flores Diaz, Brian Irving Carlsen, Marco Alejandro Ruiz Preciado, Desiré Molina Alcaide, Bowen Yang, Felix Thomas Eickemeyer

Four ZnPc-dimers with 2,5-thienyl (ZnPc-th-ZnPc 1), 2,7-fluorenyl (ZnPc-flu-ZnPc 2), 3,6-bisthienylldiketopyrrolopyrrole (ZnPc-DPP-ZnPc 3) and 1,4-phenyl (ZnPc-p-ZnPc 4) bridges have been studied as dopant-free hole transporting materials (HTMs) in perovsk ...

WILEY-V C H VERLAG GMBH2020

Interfacial and bulk properties of hole transporting materials in perovskite solar cells: spiro-MeTAD versus spiro-OMeTAD

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Elham Halvani Anaraki, Mona Shasti

Two spiro-MeTAD compounds (1 and 2) were synthesized, characterized by experimental and quantum mechanical methods, and used as hole transporting materials (HTMs) in perovskite solar cells (PSCs). The new compounds differ from spiro-OMeTAD only by the pres ...

Royal Society of Chemistry2020

Understanding the Interfaces between Triple-Cation Perovskite and Electron or Hole Transporting Material

Ulf Anders Hagfeldt, Jessica Taylor Flach

The properties of efficient solar cells fabricated with triple-cation perovskite placed between a mesoporous titania layer and a spiro-OMeTAD layer are studied by using devices either prepared under water-free drybox conditions or fabricated under ambient ...

AMER CHEMICAL SOC2020

Crown Ether Modulation Enables over 23% Efficient Formamidinium-Based Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mounir Driss Mensi, Ursula Röthlisberger, Ulf Anders Hagfeldt, Jun Ho Yum, Kevin Sivula, Marko Mladenovic, David Lyndon Emsley, Farzaneh Jahanbakhshi, Jovana Milic, Dan Ren, Aditya Mishra, Felix Thomas Eickemeyer, Hong Zhang, Michael Allan Hope, Jun Li, Anurag Krishna, Olivier Ouellette, Zhiwen Zhou

The use of molecular modulators to reduce the defect density at the surface and grain boundaries of perovskite materials has been demonstrated to be an effective approach to enhance the photovoltaic performance and device stability of perovskite solar cell ...

2020

Highly efficient and rapid manufactured perovskite solar cells via Flash InfraRed Annealing

Ulf Anders Hagfeldt, Sandy Sanchez Alonso, Michael Saliba

This work unveils how to quickly manufacture highly efficient and stable perovskite solar cells (PSCs) using the Flash InfraRed Annealing (FIRA) method. With FIRA, the titanium oxide mesoscopic layer can be synthesized in only 10 min, and the synthesis of ...

2020

Intermediate Phase Enhances Inorganic Perovskite and Metal Oxide Interface for Efficient Photovoltaics

Michael Graetzel, Ulf Anders Hagfeldt, Dominik Józef Kubicki, Wolfgang Richard Tress, David Lyndon Emsley, Claudia Esther Avalos, Zaiwei Wang, Yuhang Liu, Anand Agarwalla, Brian Irving Carlsen, Wanchun Xiang, Mona Shasti, Jiahuan Zhang, Aditya Mishra, Haizhou Lu, Ziyun Wang

Interfacial modification is crucial to fully develop the potential of semiconductor devices, including the revolutionary halide perovskite-based optoelectronics, such as photovoltaics, light-emitting diodes, and photodetectors. The all-inorganic halide per ...

CELL PRESS2020

First Report of Chenodeoxycholic Acid-Substituted Dyes Improving the Dye Monolayer Quality in Dye-Sensitized Solar Cells

Ulf Anders Hagfeldt

Chenodeoxycholic acid (CDCA) is the most used antiaggregation additive in dye-sensitized solar cells since its introduction to the field in 1993. However, effective suppression of dye aggregation comes at the cost of reduced dye loading, a lower open-circu ...

WILEY-V C H VERLAG GMBH2020

Revealing the Perovskite Film Formation Using the Gas Quenching Method by In Situ GIWAXS: Morphology, Properties, and Device Performance

Ulf Anders Hagfeldt, Sandy Sanchez Alonso, Rodrigo Szostak

The optoelectronic properties, morphology, and consequently the performance of metal halide perovskite solar cells are directly related to the crystalline phases and intermediates formed during film preparation. The gas quenching method is compatible with ...

2020

Quasi-Heteroface Perovskite Solar Cells

Ulf Anders Hagfeldt, Yi Ding, Peng Wang, Xiaoyu Zhang, Yang Li

Perovskite solar cells (PSCs) have attracted unprecedented attention due to their rapidly rising photoelectric conversion efficiency (PCE). In order to further improve the PCE of PSCs, new possible optimization path needs to be found. Here, quasi-heterofac ...

WILEY-V C H VERLAG GMBH2020

On the Mechanistic Understanding of Photovoltage Loss in Iron Pyrite Solar Cells

Ulf Anders Hagfeldt

Considering the natural abundance, the optoelectronic properties, and the electricity production cost, iron pyrite (FeS2) has a strong appeal as a solar cell material. The maximum conversion efficiency of FeS2 solar cells demonstrated to date, however, is ...

Wiley2020

A Blue Photosensitizer Realizing Efficient and Stable Green Solar Cells via Color Tuning by the Electrolyte

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Yiming Cao, Peng Wang, Yameng Ren, Dan Zhang

Semitransparent dye-sensitized solar cells (DSCs) are appealing as aesthetically pleasing and colorful see-through photovoltaics. Green semitransparent DSCs have been presented, but the best ones rely on green zinc porphyrin photosensitizers and high volat ...

Wiley-V C H Verlag Gmbh2020

Blue Photosensitizer with Copper(II/I) Redox Mediator for Efficient and Stable Dye‐Sensitized Solar Cells

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Jean-David Décoppet, Ulf Anders Hagfeldt, Yiming Cao, Natalie Flores Diaz, George Cameron Fish, Yameng Ren, Dan Zhang

Dye-sensitized solar cells (DSCs) based on copper(II/I) redox mediators have recently achieved notable performance progress through tailoring the ligand structure of the copper complexes, exploiting cosensitization, and introducing an advanced device struc ...

2020

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

Low-temperature carbon-based electrodes in perovskite solar cells

Ulf Anders Hagfeldt, Konrad Wojciechowski, Dmitry Bogachuk, Bowen Yang, Jaekeun Lim

Carbon-based electrodes have been widely applied in perovskite solar cells (PSCs) because of their chemical inertness and compatibility with up-scalable techniques, signifying their solid potential for mass-production. The material scarcity and complexity ...

ROYAL SOC CHEMISTRY2020

Postpassivation of Multication Perovskite with Rubidium Butyrate

Ulf Anders Hagfeldt, Rodrigo Szostak

Many multication perovskites for highly stable and efficient solar cells benefit from rubidium iodide introduced in the precursor solution. It is well-known that Rb+ influences positively the optoelectronic and mobility properties and has a direct effect u ...

AMER CHEMICAL SOC2020

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

Molecular Engineering of Simple Metal-Free Organic Dyes Derived from Triphenylamine for Dye-Sensitized Solar Cell Applications

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Farzan Jazaeri, Yasemin Saygili, Parnian Ferdowsi, Yuhang Liu

Two new metal-free organic sensitizers, L156 and L224, were designed, synthesized, and characterized for application in dye-sensitized solar cells (DSCs). The structures of the dyes contain a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4- ...

WILEY-V C H VERLAG GMBH2020

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