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Kyung Taek Cho

Cette personne a quitté l’EPFL

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Publications associées (39)

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Band-bending induced passivation: high performance and stable perovskite solar cells using a perhydropoly(silazane) precursor

Mohammad Khaja Nazeeruddin, Mounir Driss Mensi, Valentin Ianis Emmanuel Queloz, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Cristina Roldán Carmona, Aron Joel Huckaba, Giulia Grancini, Yi Zhang, Hiroyuki Kanda, Nadja Isabelle Desiree Klipfel, Mo Li

Surface passivation of the perovskite photo absorber is a key factor to improve the photovoltaic performance. So far robust passivation strategies have not yet been revealed. Here, we demonstrate a successful passivation strategy which controls the Fermi-l ...

2020

Dimensionally Engineered Perovskite Heterostructure for Photovoltaic and Optoelectronic Applications

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

Although 2D|3D has shown potential for application in multifunctional devices, the principle of operation for multifunction devices (SOLAR Cell-LED: SOLED) has not yet been revealed. However, most studies have reported that the devices have only one auspic ...

2019

Measurements of isospin asymmetry and difference of direct CP asymmetries in inclusive B -> X-s gamma decays

Olivier Schneider, Sun Hee Kim, Steve Michel Berger, Mingkui Wang, Chao Wang, Yong Chan Choi, Arnaud Michel Gelb, Kyung Taek Cho, Jun Yong Kim, Johannes Julius Thomas Marinus Swartjes, Linlin Cao, Carsten Hao Ye Chong, Tara Nanut, Martin Lubej, Chang-Hyun Park, Yifei Guan, Yiming Li

We report measurements of isospin asymmetry Delta(0-) and difference of direct CP asymmetries Delta A(CP) between charged and neutral B -> X-s gamma decays. This analysis is based on the data sample containing 772 x 10(6)B (B) over bar pairs that was colle ...

American Physical Society2019

Observation of a new structure near 10.75 GeV in the energy dependence of the e(+)e(-)-> Upsilon (nS)pi(+)pi(-) (n=1, 2, 3) cross sections

Olivier Schneider, Sun Hee Kim, Mingkui Wang, Chao Wang, Kyung Taek Cho

We report a new measurement of the e(+)e(-)-> Upsilon(nS)pi(+)pi(-) (n = 1, 2, 3) cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We observe a new structure in ...

Springer Nature2019

Search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi(-) decays

Olivier Schneider, Sun Hee Kim, Mingkui Wang, Chao Wang, Yong Chan Choi, Kyung Taek Cho, Jun Yong Kim, Johannes Julius Thomas Marinus Swartjes, Mithilesh Nayak, Linlin Cao, Carsten Hao Ye Chong, Yiming Li

We report the results of a search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi thorn p-decays. This study is based on a data sample corresponding to an integrated luminosity of 711 fb(-1), collected at the Upsilon(4S) resonance with the Belle detector a ...

American Physical Society2019

Composition and Interface Engineering of Organic-Inorganic Hybrid Perovskites to Improve Photovoltaic Performance and Stability

Kyung Taek Cho

Faced with the growing demands for energy in modern society, organic-inorganic metal halide perovskite materials have recently fascinated the photovoltaics (PV) research community due to a combination of their high quality optoelectronic properties and the ...

EPFL2018

Perovskite Solar Cells Employing Molecularly Engineered Zn(II) Phthalocyanines as Hole-transporting Materials

Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Kyung Taek Cho

Amino donor groups-substituted zinc(II) phthalocyanines (ZnPcs) BI25, BL07 and BL08 were obtained via cyclotetramerization of suitable phthalonitriles that were synthesized by Pd catalyzed amination reaction between 4-iodophthalonitrile and a selected seco ...

Elsevier Science Bv2016

From Nano- to Micrometer Scale: The Role of Antisolvent Treatment on High Performance Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Francesco Stellacci, Peng Gao, Evangelia-Nefeli Athanasopoulou, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini, Yi Zhang, Pascal Alexander Schouwink

To date, antisolvent treatment has become one of the most important means to fabricate high efficiency perovskite solar cells (PSCs); however, the few reported antisolvents have not been analyzed on a uniform platform, and there is hitherto no clear reason ...

American Chemical Society2017

A Facile Preparative Route of Nanoscale Perovskites over Mesoporous Metal Oxide Films and Their Applications to Photosensitizers and Light Emitters

Mohammad Khaja Nazeeruddin, Emad Oveisi, Valentin Ianis Emmanuel Queloz, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Iwan Zimmermann, Aron Joel Huckaba, Giulia Grancini, So-Min Yoo

By two‐step sequential Pb2+ adsorption and reaction with methylammonium‐iodide (MAI) or ‐bromide (MABr) at a low concentration level of 0.06–0.10 m over mesoporous TiO2 or ZrO2 film, a well‐defined nanoscale CH3NH3PbI3 (MAPbI3) photosensitizer or CH3NH3PbB ...

2018

Water-Repellent Low-Dimensional Fluorous Perovskite as Interfacial Coating for 20% Efficient Solar Cells

Mohammad Khaja Nazeeruddin, Andreas Stephan Lesch, Kyung Taek Cho, Iwan Zimmermann, Giulia Grancini, Yi Zhang

Hybrid perovskite solar cells have been capturing an enormous research interest in the energy sector due to their extraordinary performances and ease of fabrication. However, low device lifetime, mainly due to material and device degradation upon water exp ...

American Chemical Society (ACS)2018

Search for CP violation with kinematic asymmetries in the D-0 -> K+K- pi(+)pi(-) decay

Olivier Schneider, Sun Hee Kim, Mingkui Wang, Chao Wang, Kyung Taek Cho, Jun Yong Kim, Mithilesh Nayak, Yifei Guan, Yiming Li

We search for CP violation in the singly-Cabibbo-suppressed decay D-0 -> K+K-pi(+)pi(-) using data corresponding to an integrated luminosity of 988 fb(-1) collected by the Belle detector at the KEKB e(+)e(-). We measure a set of five kinematically dependen ...

American Physical Society2019

Intercalation makes the difference with TiS2: Boosting electrocatalytic water oxidation activity through Co intercalation

Mohammad Khaja Nazeeruddin, Emad Oveisi, Kyung Taek Cho, Aron Joel Huckaba

Intercalated and unmodified TiS2 nanomaterials were synthesized and characterized by UV-Visible-NIR spectroscopy, Powder X-Ray Diffraction, and X-Ray Photoelectron and Ultraviolet Photoelectron Spectroscopy. Photoelectron spectroscopy measurements indicate ...

2018

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

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

Efficient Planar Perovskite Solar Cells Using Passivated Tin Oxide as an Electron Transport Layer

Mohammad Khaja Nazeeruddin, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Aron Joel Huckaba, Marco Calizzi

Planar perovskite solar cells using low-temperature atomic layer deposition (ALD) of the SnO2 electron transporting layer (ETL), with excellent electron extraction and hole-blocking ability, offer significant advantages compared with high-temperature depos ...

2018

Optoelectronic Properties of Layered Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Yonghui Lee, Tom Theodorus Antonius Lummen, Kyung Taek Cho, Alexandre Vincent Laurent Chenu, Sanghyun Paek

Herein, the optoelectronic properties of interface-engineered perovskite 2D|3D-heterojunction structure solar cells are reported. The reciprocity theorem is applied to determine the maximum open-circuit voltage (V-oc) the device can deliver under solar ill ...

2019

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

Molecular engineering of face-on oriented dopant-free hole transporting material for perovskite solar cells with 19% PCE

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini

Through judicious molecular engineering, novel dopant-free star-shaped D-pi-A type hole transporting materials coded KR355, KR321, and KR353 were systematically designed, synthesized and characterized. KR321 has been revealed to form a particular face-on o ...

Royal Society of Chemistry2017

Analysis of Photoinduced Carrier Recombination Kinetics in Flat and Mesoporous Lead Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Kyung Taek Cho

In this work, we analyze the carrier recombination kinetics and the associated charge carrier density in methylammonium lead iodide perovskite (MAPI) solar cells that use mesoporous TiO2, as selective contact (m-MAPI) and flat solar cells (without the meso ...

Amer Chemical Soc2017

Molecular engineering of enamine-based small organic compounds as hole-transporting materials for perovskite solar cells

Mohammad Khaja Nazeeruddin, Kyung Taek Cho, Sanghyun Paek, Michael Saliba

The search for new classes of hole transporting materials (HTMs) is a very important task on the way towards commercialization of perovskite solar cells (PSCs). In this work, the synthesis and performance in PSCs of new enamine-based HTMs are presented. Th ...

Royal Society of Chemistry2019