Publications by Ulf Anders Hagfeldt

Multifunctional sulfonium-based treatment for perovskite solar cells with less than 1% efficiency loss over 4,500-h operational stability tests

Ulf Anders Hagfeldt, Bowen Yang, Yeonju Kim, Jiajia Suo

The stabilization of grain boundaries and surfaces of the perovskite layer is critical to extend the durability of perovskite solar cells. Here we introduced a sulfonium-based molecule, dimethylphenethylsulfonium iodide (DMPESI), for the post-deposition tr ...

Nature Portfolio2024

Research data supporting "High carrier mobility along the [111] orientation in Cu2O photoelectrodes"

Michael Graetzel, Paul Joseph Dyson, Ulf Anders Hagfeldt, Jingshan Luo, Linfeng Pan, Lu Chen, Dan Ren, Meng Xia

Included in the dataset are detailed information into the crystallography, morphology, electronic properties, (photo)electrochemical and carrier dynamics of both single-crystal Cu2O thin films and polycrystalline Cu2O with favored crystal orientations. Mul ...

Apollo - University of Cambridge Repository2024

High carrier mobility along the [111] orientation in Cu2O photoelectrodes

Michael Graetzel, Paul Joseph Dyson, Ulf Anders Hagfeldt, Linfeng Pan, Lu Chen, Dan Ren, Meng Xia

Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight(1,2). Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovolta ...

Nature Portfolio2024

[Correction] High carrier mobility along the [111] orientation in Cu2O photoelectrodes (vol 628, pg 765, 2024)

Michael Graetzel, Paul Joseph Dyson, Ulf Anders Hagfeldt, Linfeng Pan, Lu Chen, Dan Ren, Meng Xia

NATURE PORTFOLIO2024

A universal ligand for lead coordination and tailored crystal growth in perovskite solar cells

Ulf Anders Hagfeldt, Bowen Yang, Jiajia Suo

Chemical environment and precursor-coordinating molecular interactions within a perovskite precursor solution can lead to important implications in structural defects and crystallization kinetics of a perovskite film. Thus, the opto-electronic quality of s ...

Royal Soc Chemistry2024

Reinforced polypyrrole with 2D graphene flakes decorated with interconnected nickel-tungsten metal oxide complex toward superiorly stable supercapacitor (vol 418, 129396, 2021)

Ulf Anders Hagfeldt, Seyyed Alireza Hashemi

ELSEVIER SCIENCE SA2023

Cooperative passivation of perovskite solar cells by alkyldimethylammonium halide amphiphiles

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Thomas Paul Baumeler, David Lyndon Emsley, Essa Awadh R Alharbi, Mathias Dankl, Aditya Mishra, Felix Thomas Eickemeyer, Michael Allan Hope, Anurag Krishna, Olivier Ouellette, Lukas Pfeifer, Nikolaos Lempesis, Georgios Kakavelakis

2023

Understanding and decoupling the role of wavelength and defects in light-induced degradation of metal-halide perovskites

Michael Graetzel, Ulf Anders Hagfeldt, Anurag Krishna

Light-induced degradation in metal halide perovskites is a major concern that can potentially hamper the commercialization of perovskite optoelectronic devices. The phenomena viz. ion migration, phase segregation, and defect intolerance are believed to be ...

Royal Soc Chemistry2023

Coordination modulated passivation for stable organic-inorganic perovskite solar cells

Ulf Anders Hagfeldt, Yeonju Kim, Jaeki Jeong

Despite the recent exceptional rise in power conversion efficiency of perovskite solar cells (PSCs), surface defects and ion migration related instability are still present in PSCs. The chain length and binding energy of the passivation material play impor ...

2023

Mitigating the Heterointerface Driven Instability in Perovskite Photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Essa Awadh R Alharbi, Mathias Dankl, Felix Thomas Eickemeyer, Hong Zhang, Anurag Krishna

Metal halide perovskites have thepotential to revolutionizethefield of photovoltaics, though limited stability has impeded commercialexploitation. The soft heterointerface between the perovskite andcharge-transporting layer is one of the major bottlenecks ...

AMER CHEMICAL SOC2023

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

High-Work-Function 2D Perovskites as Passivation Agents in Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Joseph Dyson, Ulf Anders Hagfeldt, Antoine Philippe Van Muyden, Farzaneh Fadaei Tirani, Erfan Shirzadi, Hiroyuki Kanda, Brian Irving Carlsen, Fatemeh Ansari, Felix Thomas Eickemeyer, Olivier Ouellette, Hiroaki Jinno

Various approaches have been employed to passivate the defects in perovskite films used in perovskite solar cells (PSCs). However, the passivation mechanism is often unclear at a molecular level, and the reason for enhanced PSC performance often remains el ...

Amer Chemical Soc2023

Overcome Low Intrinsic Conductivity of NiOx Through Triazinyl Modification for Highly Efficient and Stable Inverted Perovskite Solar Cells

Ulf Anders Hagfeldt, Hui Chen, Jiabao Yang, Tong Wang, Bowen Yang

Nickel oxide (NiOx) is a promising hole transport material in inverted organic-inorganic metal halide perovskite solar cells. However, its low intrinsic conductivity hinders its further improvement in device performance. Here, we employ a trimercapto-s-tri ...

WILEY-V C H VERLAG GMBH2022

Inhibiting metal-inward diffusion-induced degradation through strong chemical coordination toward stable and efficient inverted perovskite solar cells

Ulf Anders Hagfeldt, Bowen Yang

The inward diffusion of metal electrodes is one of the main reasons for the deterioration of the long-term device stability of perovskite solar cells (PSCs). Thus, herein, we adopt a simple additive engineering strategy to modify the barrier material batho ...

ROYAL SOC CHEMISTRY2022

Critical Role of Removing Impurities in Nickel Oxide on High-Efficiency and Long-Term Stability of Inverted Perovskite Solar Cells

Ulf Anders Hagfeldt

The performance enhancement of inverted perovskite solar cells applying nickel oxide (NiOx) as the hole transport layer (HTL) has been limited by impurity ions (such as nitrate ions). Herein, we have proposed a strategy to obtain high-quality NiOx nanopart ...

Wiley-VCH Verlag GmbH2022

Interfacial engineering from material to solvent: A mechanistic understanding on stabilizing alpha-formamidinium lead triiodide perovskite photovoltaics

Michael Graetzel, Ulf Anders Hagfeldt, Bowen Yang, Jiajia Suo, Jaeki Jeong

Formamidinium lead triiodide (FAPbI3) has recently been considered as the most promising candidate to achieve highly efficient perovskite solar cells (PSCs). Excitingly, the state-of-the-art highest efficiency of FAPbI3 based PSCs have reached over 25%. Ho ...

Elsevier2022

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

A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Sandy Sanchez Alonso, Narges Yaghoobi Nia, Linfeng Pan, Paramvir Ahlawat, Viacheslav Bolnykh, Dan Ren, Masaud Hassan S Almalki, Hong Zhang, Anurag Krishna, Tzu-Sen Su

Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a ground-breaking strategy for eco-friendly and cost-effective fabrication of highly efficient ...

Nature Research2022

Perovskite Solar Cells with Carbon-Based Electrodes - Quantification of Losses and Strategies to Overcome Them

Ulf Anders Hagfeldt, Dmitry Bogachuk, Bowen Yang, Jiajia Suo

Carbon-based electrodes represent a promising approach to improve stability and up-scalability of perovskite photovoltaics. The temperature at which these contacts are processed defines the absorber grain size of the perovskite solar cell: in cells with lo ...

WILEY-V C H VERLAG GMBH2022

Strain effects on halide perovskite solar cells

Mohammad Khaja Nazeeruddin, Ulf Anders Hagfeldt, Hobeom Kim, Bowen Yang, Jiajia Suo

Halide perovskite solar cells (PSCs) have achieved power conversion efficiencies (PCEs) approaching 26%, however, the stability issue hinders their commercialization. Due to the soft ionic nature of perovskite materials, the strain effect on perovskite fil ...

Royal Society of Chemistry2022