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Yonghui Lee

Cette personne n’est plus à l’EPFL

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Publications associées (41)

Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces

Mohammad Khaja Nazeeruddin, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Michael Saliba, Giulia Grancini

With a power conversion efficiency (PCE) exceeding 22%, perovskite solar cells (PSCs) have thrilled photovoltaic research. However, the interface behavior is still not understood and is a hot topic of research: different processes occur over a hierarchy of ...

Wiley-Blackwell2017

Deep level trapped defect analysis in CH3NH3PbI3 perovskite solar cells by deep level transient spectroscopy

Mohammad Khaja Nazeeruddin, Yonghui Lee

We report the presence of defects in CH3NH3PbI3, which is one of the main factors that deteriorates the performance of perovskite solar cells. Although the efficiency of the perovskite solar cells has been improved by curing defects using various methods, ...

Royal Soc Chemistry2017

Highly efficient perovskite solar cells with a compositionally engineered perovskite/hole transporting material interface

Mohammad Khaja Nazeeruddin, Peng Gao, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Cristina Roldán Carmona, Giulia Grancini

Perovskite solar cells (PSCs) have experienced an outstanding advance in power conversion efficiency (PCE) by optimizing the perovskite layer morphol., compn., interfaces, and charge collection efficiency. To enhance PCE, here we developed a new method i.e ...

Royal Soc Chemistry2017

Dopant-Free Hole-Transporting Materials for Stable and Efficient Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Christian Ludwig, Paul Gratia, Emad Oveisi, Peng Gao, Peng Qin, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek

Molecularly engineered novel dopant-free hole-transporting materials for perovskite solar cells (PSCs) combined with mixed-perovskite (FAPbI(3))(0.85)(MAPbBr(3))(0.15) (MA: CH3NH3+, FA: NH=CHNH3+) that exhibit an excellent power conversion efficiency of 18 ...

Wiley-V C H Verlag Gmbh2017

Beneficial Role of Reduced Graphene Oxide for Electron Extraction in Highly Efficient Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini

In this work we systematically investigated the role of reduced graphene oxide (rGO) in hybrid perovskite solar cells (PSCs). By mixing rGO within the mesoporous TiO2 (m-TiO2) matrix, highly efficient solar cells with power conversion efficiency values up ...

Wiley-VCH Verlag Berlin2016

A highly hindered bithiophene-functionalized dispiro-oxepine derivative as an efficient hole transporting material for perovskite solar cells

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Muhammad Sohail

Dimethoxydiphenylamine-substituted dispiro-oxepine derivative 2,2',7,7'-tetrakis-(N,N'-di-4-methoxyphenylamine)dispiro-[fluorene-9,4'-dithieno(3,2-c:2',3'-e]oxepine-6',9 ''-fluorene] (DDOF) has been designed and synthesized using a facile synthetic route. ...

Royal Society of Chemistry2016

Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Peng Gao, Yonghui Lee, Jingshan Luo, Kyung Taek Cho, Minkyu Son, Jiyoun Seo

The Al2O3 passivation layer is beneficial for mesoporous TiO2-based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of th ...

Wiley-V C H Verlag Gmbh2016

Ionic polarization-induced current–voltage hysteresis in CH3NH3PbX3 perovskite solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Thomas Moehl, Peng Gao, Yonghui Lee, Simone Meloni, Wolfgang Richard Tress, Marius Franckevicius, Michael Saliba

CH3NH3PbX3 (MAPbX(3)) perovskites have attracted considerable attention as absorber materials for solar light harvesting, reaching solar to power conversion efficiencies above 20%. In spite of the rapid evolution of the efficiencies, the understanding of b ...

Nature Research2016

Intrinsic Halide Segregation at Nanometer Scale Determines the High Efficiency of Mixed Cation/Mixed Halide Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Kevin Sivula, Xavier Adrian Jeanbourquin, Paul Gratia, Yonghui Lee, Iwan Zimmermann, Giulia Grancini, Filippo de Angelis

Compositional engineering of a mixed cation/mixed halide perovskite in the form of (FAP-bI(3))(0.85)(MAPbBr(3))(0.15) is one of the most effective strategies to obtain record-efficiency perovskite solar cells. However, the perovskite self-organization upon ...

2016

PbI2–HMPA Complex Pretreatment for Highly Reproducible and Efficient CH3NH3PbI3 Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Quentin Thomas Jeangros, Emad Oveisi, Peng Gao, Yonghui Lee, Sanghyun Paek, Giulia Grancini, Yi Zhang

Interfacial engineering of the meso-TiO2 surface through a modified sequential deposition procedure involving a novel PbI2–HMPA complex pretreatment is conducted as a reproducible method for preparing MAPbI3 based perovskite solar cells providing the highe ...

2016

Charge Transfer Dynamics from Organometal Halide Perovskite to Polymeric Hole Transport Materials in Hybrid Solar Cells

Mohammad Khaja Nazeeruddin, Jan Cornelius Brauer, Natalie Renuka Banerji, Yonghui Lee

Organometal halide perovskites have emerged as promising next-generation solar cell technologies presenting outstanding efficiencies. However, many questions concerning their working principles remain to be answered. Here, we present a detailed study of ho ...

Amer Chemical Soc2015

Improved environmental stability of organic lead trihalide perovskite-based photoactive-layers in the presence of mesoporous TiO2

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yonghui Lee

Impressive hybrid photovoltaic device performances have been realised with the methylammonium lead triiodide (MAPbI(3)) perovskite absorber in a wide range of device architectures. However, the question as to which of these systems represents the most comm ...

Royal Society of Chemistry2015

Unraveling the Reasons for Efficiency Loss in Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Robin Humphry-Baker, Peng Gao, Yonghui Lee, Jingshan Luo

The effect of the presence of unreacted PbI2 on the perovskite solar cells efficiency is reported. N,N-Dimethylformamide vapor treatment is introduced to study the influence of complete conversion to a power conversion efficiency of the device. It is disco ...

Wiley-Blackwell2015

Targeting Ideal Dual-Absorber Tandem Water Splitting Using Perovskite Photovoltaics and CuInxGa1-xSe2 Photocathodes

Michael Graetzel, Mohammad Khaja Nazeeruddin, Marcel Roland Schreier, Stanley David Tilley, Yonghui Lee, Matthew Thomas Mayer, Jingshan Luo, Kunwu Fu

Efficient sunlight-driven water splitting devices can be achieved by pairing two absorbers of different optimized bandgaps in an optical tandem design. With tunable absorption ranges and cell voltages, organic-inorganic metal halide perovskite solar cells ...

Wiley-V C H Verlag Gmbh2015

Efficient Perovskite Solar Cells with 13.63% Efficiency Based on Planar Triphenylamine Hole Conductors

Mohammad Khaja Nazeeruddin, Yonghui Lee, Sanghyun Paek

A new type of hole transporting material (HTMs) with an incorporated planar amine or triphenylamine as a core unit have been prepared. The two amine derivatives were demonstrated to be efficient hole transporting materials in fabricating solid-state organi ...

Wiley-Blackwell2014

Strong Photocurrent Amplification in Perovskite Solar Cells with a Porous TiO2 Blocking Layer under Reverse Bias

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Thomas Moehl, Leo-Philipp Heiniger, Mohammad Ibrahim Dar, Konrad Domanski, Fabrizio Giordano, Yonghui Lee, Jeong-Hyeok Im

We investigate two different types of TiO2 blocking layer (BL) deposition techniques commonly used in solid-state methylammonium lead triiodide perovskite (MaPbI(3))-based solar cells. Although these BLs lead to similar photovoltaic device performance, the ...

Amer Chemical Soc2014

Perovskite solar cells employing organic charge-transport layers

Michael Graetzel, Mohammad Khaja Nazeeruddin, Aswani Yella, Yonghui Lee

Thin-film photovoltaics play an important role in the quest for clean renewable energy. Recently, methylammonium lead halide perovskites were identified as promising absorbers for solar cells(1). In the three years since, the performance of perovskite-base ...

Nature Publishing Group2014

Efficient inorganic-organic hybrid heterojunction solar cells containing perovskite compound and polymeric hole conductors

Michael Graetzel, Mohammad Khaja Nazeeruddin, Arpita Sarkar, Yonghui Lee

Inorganic-organic hybrid structures have become innovative alternatives for next-generation dye-sensitized solar cells, because they combine the advantages of both systems. Here, we introduce a layered sandwich-type architecture, the core of which comprise ...

Nature Publishing Group2013

Hole-conducting mediator for stable Sb2S3-sensitized photoelectrochemical solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yonghui Lee

Iodide redox (3I(-)/I-3(-)), polysulfide redox (S2-/S-x(2-)), organic redox [TMTU/TMFDS2+: tetramethylthiourea/tetramethylformaminium-bis(trifluoromethanesulfonyl) imide], ferrocene redox (Fc/Fc(+)), nickel redox [Ni(II)/Ni(III)], and cobalt redox [Co(II)/ ...

Royal Society of Chemistry2012

Toward Interaction of Sensitizer and Functional Moieties in Hole-Transporting Materials for Efficient Semiconductor-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yonghui Lee

Sb2S3-sensitized mesoporous-TiO2 solar cells using several conjugated polymers as hole-transporting materials (HTMs) are fabricated. We found that the cell performance was strongly cc rrelated with the chemical interaction at the interface of Sb2S3 as sens ...

American Chemical Society2011

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