Michael Graetzel
École Polytechnique Fédérale de Lausanne
H-index: 299
Europe-Switzerland
Professor Information
University | École Polytechnique Fédérale de Lausanne |
---|---|
Position | Professor |
Citations(all) | 475906 |
Citations(since 2020) | 148226 |
Cited By | 394526 |
hIndex(all) | 299 |
hIndex(since 2020) | 170 |
i10Index(all) | 1505 |
i10Index(since 2020) | 1011 |
University Profile Page | École Polytechnique Fédérale de Lausanne |
Research & Interests List
Solar energy conversion
Top articles of Michael Graetzel
Buried‐Interface Engineering Enables Efficient and 1960‐Hour ISOS‐L‐2I Stable Inverted Perovskite Solar Cells
High‐performance perovskite solar cells (PSCs) typically require interfacial passivation, yet this is challenging for the buried interface, owing to the dissolution of passivation agents during the deposition of perovskites. Here, this limitation is overcome with in situ buried‐interface passivation—achieved via directly adding a cyanoacrylic‐acid‐based molecular additive, namely BT‐T, into the perovskite precursor solution. Classical and ab initio molecular dynamics simulations reveal that BT‐T spontaneously may self‐assemble at the buried interface during the formation of the perovskite layer on a nickel oxide hole‐transporting layer. The preferential buried‐interface passivation results in facilitated hole transfer and suppressed charge recombination. In addition, residual BT‐T molecules in the perovskite layer enhance its stability and homogeneity. A power‐conversion efficiency (PCE) of 23.48% for 1.0 cm2 inverted …
Authors
Lin Li,Mingyang Wei,Virginia Carnevali,Haipeng Zeng,Miaomiao Zeng,Ranran Liu,Nikolaos Lempesis,Felix Thomas Eickemeyer,Long Luo,Lorenzo Agosta,Mathias Dankl,Shaik M Zakeeruddin,Ursula Roethlisberger,Michael Grätzel,Yaoguang Rong,Xiong Li
Journal
Advanced Materials
Published Date
2024/3
High carrier mobility along the [111] orientation in Cu2O photoelectrodes
Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight,. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials, –. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111 …
Authors
Linfeng Pan,Linjie Dai,Oliver J Burton,Lu Chen,Virgil Andrei,Youcheng Zhang,Dan Ren,Jinshui Cheng,Linxiao Wu,Kyle Frohna,Anna Abfalterer,Terry Chien-Jen Yang,Wenzhe Niu,Meng Xia,Stephan Hofmann,Paul J Dyson,Erwin Reisner,Henning Sirringhaus,Jingshan Luo,Anders Hagfeldt,Michael Grätzel,Samuel D Stranks
Journal
Nature
Published Date
2024/4/25
Interfacial Modulation through Mixed‐Dimensional Heterostructures for Efficient and Hole Conductor‐Free Perovskite Solar Cells
Perovskite solar cells have led the new surge of solar energy research. However, their instability is a pressing issue mostly attributed to the perovskite interface with charge‐selective transport layers. In this work, diethylammonium iodide (DEAI) surface treatment is used to mitigate interfacial non‐radiative recombination losses by forming a mixed phase of layered perovskite on the surface. This results in enhanced device performance with the power conversion efficiency of 23.3% and improved operational stability under thermal stress. Moreover, the DEAI treatment facilitates interfacial hole transfer, enabling a carbon‐based hole transport layer‐free perovskite solar cell with a power conversion efficiency of 15.6%.
Authors
Masaud Almalki,Mohammad Hayal Alotaibi,Anwar Q Alanazi,Felix T Eickemeyer,Sultan M Alenzi,Yahya A Alzahrani,Laura Piveteau,Ahmed Y Alymani,Abdulrahman Albadri,Hamad Albrithen,Jovana V Milić,Shaik M Zakeeruddin,Hong Zhang,Michael Grätzel
Journal
Advanced Functional Materials
Published Date
2024/2
Durable Perovskite Solar Cells with 24.5% Average Efficiency: the Role of Rigid Conjugated Core in Molecular Semiconductors
Efficient and robust n‐i‐p perovskite solar cells necessitate superior organic hole‐transport materials with both mechanical and electronic prowess. Deciphering the structure−property relationship of these materials is crucial for practical perovskite solar cell applications. Through direct arylation, we synthesized two high glass transition temperature molecular semiconductors, DBC‐ETPA (202 °C) and TPE‐ETPA (180 °C), using dibenzo[g,p]chrysene (DBC) and 1,1,2,2‐tetraphenylethene (TPE) tetrabromides with triphenylene–ethylenedioxythiophene‐dimethoxytriphenylamine (ETPA). In comparison to spiro‐OMeTAD, both semiconductors exhibit shallower HOMO energy levels, resulting in increased hole densities (generated by air oxidation doping) and accelerated hole extraction from photoexcited perovskite. Experimental and theoretical studies highlight the more rigid DBC core, enhancing hole mobility due to …
Authors
Ming Ren,Lingyi Fang,Yuyan Zhang,Felix T Eickemeyer,Yi Yuan,Shaik M Zakeeruddin,Michael Grätzel,Peng Wang
Journal
Advanced Materials
Published Date
2024/4/17
Infrared-reflective ultrathin-metal-film-based transparent electrode with ultralow optical loss for high efficiency in solar cells
In this work we study in-depth the antireflection and filtering properties of ultrathin-metal-film-based transparent electrodes (MTEs) integrated in thin-film solar cells. Based on numerical optimization of the MTE design and the experimental characterization of thin-film perovskite solar cell (PSC) samples, we show that reflection in the visible spectrum can be strongly suppressed, in contrast to common belief (due to the compact metal layer). The optical loss of the optimized electrode (~ 2.9%), composed of a low-resistivity metal and an insulator, is significantly lower than that of a conventional transparent conductive oxide (TCO ~ 6.3%), thanks to the very high transmission of visible light within the cell (> 91%) and low thickness (< 70 nm), whereas the reflection of infrared light (~ 70%) improves by > 370%. To assess the application potentials, integrated current density > 25 mA/cm2, power conversion …
Authors
George Perrakis,Anna C Tasolamprou,George Kakavelakis,Konstantinos Petridis,Michael Graetzel,George Kenanakis,Stelios Tzortzakis,Maria Kafesaki
Journal
Scientific Reports
Published Date
2024/1/4
Photo-doping of spiro-OMeTAD for highly stable and efficient perovskite solar cells
A widely used component of high-efficiency perovskite solar cells (PSCs) is the molecular hole-transport material (HTM) spiro-OMeTAD. This organic solid needs to be p-doped to acquire sufficient hole conductivity. However, the conventional doping method using LiTFSI in the air is slow, sensitive to the environment, and may lead to the deterioration of the PSCs by unintended oxidation or dopant migration. It is thus highly desirable to develop fast doping approaches that avoid exposing the PSC to ambient air and easy-to-move dopant ions. We report here that light absorption by spiro-OMeTAD itself triggers redox photochemistry that has so far been ignored. Strikingly, we found that Y(III) or La(III)-tBP complexes catalyze the symmetry-breaking charge separation of photo-excited spiro-OMeTAD, resulting in the efficient p-doping of the HTM. Using this photo-redox process, we realize PSCs with superior stability over …
Authors
Seul-Gi Kim,George C Fish,Etienne Socie,Aaron T Terpstra,Dong-Am Park,Kai Zhu,Michael Grätzel,Jacques-E Moser,Nam-Gyu Park
Journal
Joule
Published Date
2024/4/15
Modulation of Ionically Generated Space Charge Effects at Hybrid Perovskite and Oxide Interfaces via Surface Modification
Interfacial space charges significantly influence transport and recombination of charge carriers in optoelectronic devices. Due to the mixed ionic‐electronic conducting properties of halide perovskites, not only electronic effects, but also ionic interactions at their interfaces need to be considered in the analysis of space charges. Understanding of these interactions and their control is currently missing. This study elucidates the ionic effects on space charge formation at the interface between methylammonium lead iodide (MAPI) and alumina, and its modulation through surface modification using organic molecules. Embedding insulating alumina nanoparticles within MAPI films leads to enhancement of the electronic conductivity. This effect is consistent with the formation of an interfacial inversion layer in MAPI and can only be explained on the basis of ionic interactions. Such an effect is attenuated by surface …
Authors
Mina Jung,Masaud Almalki,Michael Graetzel,Davide Moia,Joachim Maier
Journal
Advanced Materials Interfaces
Published Date
2024
Research data supporting" High carrier mobility along the [111] orientation in Cu2O photoelectrodes"
Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] orientation was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm− 2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.
Authors
Linfeng Pan,Linjie Dai,Oliver J Burton,Lu Chen,Virgil Andrei,Youcheng Zhang,Dan Ren,Jinshui Cheng,Linxiao Wu,Kyle Frohna,Anna Abfalterer,Terry Chien-Jen Yang,Wenzhe Niu,Meng Xia,Stephan Hofmann,Paul J Dyson,Erwin Reisner,Henning Sirringhaus,Jingshan Luo,Anders Hagfeldt,Michael Grätzel,Samuel D Stranks
Published Date
2024/3/25
Professor FAQs
What is Michael Graetzel's h-index at École Polytechnique Fédérale de Lausanne?
The h-index of Michael Graetzel has been 170 since 2020 and 299 in total.
What are Michael Graetzel's top articles?
The articles with the titles of
Buried‐Interface Engineering Enables Efficient and 1960‐Hour ISOS‐L‐2I Stable Inverted Perovskite Solar Cells
High carrier mobility along the [111] orientation in Cu2O photoelectrodes
Interfacial Modulation through Mixed‐Dimensional Heterostructures for Efficient and Hole Conductor‐Free Perovskite Solar Cells
Durable Perovskite Solar Cells with 24.5% Average Efficiency: the Role of Rigid Conjugated Core in Molecular Semiconductors
Infrared-reflective ultrathin-metal-film-based transparent electrode with ultralow optical loss for high efficiency in solar cells
Photo-doping of spiro-OMeTAD for highly stable and efficient perovskite solar cells
Modulation of Ionically Generated Space Charge Effects at Hybrid Perovskite and Oxide Interfaces via Surface Modification
Research data supporting" High carrier mobility along the [111] orientation in Cu2O photoelectrodes"
...
are the top articles of Michael Graetzel at École Polytechnique Fédérale de Lausanne.
What are Michael Graetzel's research interests?
The research interests of Michael Graetzel are: Solar energy conversion
What is Michael Graetzel's total number of citations?
Michael Graetzel has 475,906 citations in total.