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Jun Ho Yum

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Publications associées (128)

Establishing Stability in Organic Semiconductor Photocathodes for Solar Hydrogen Production

Jun Ho Yum, Kevin Sivula, Florian Le Formal, Muhammad Aiman Bin Rahmanudin Hamdan, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Yongpeng Liu, Rebekah Anne Wells, Florent Alexandre Boudoire, Han-Hee Cho

As organic semiconductors attract increasing attention to application in the fields of bioelectronics and artificial photosynthesis, understanding the factors that determine their robust operation in direct contact with aqueous electrolytes becomes a criti ...

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

Passivation Mechanism Exploiting Surface Dipoles Affords High-Performance Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Thomas La Grange, Paul Joseph Dyson, Ulf Anders Hagfeldt, Jun Ho Yum, Kevin Sivula, Kazuteru Nonomura, Erfan Shirzadi, Fatemeh Ansari

The employment of 2D perovskites is a promising approach to tackling the stability and voltage issues inherent in perovskite solar cells. It remains unclear, however, whether other perovskites with different dimensionalities have the same effect on efficie ...

AMER CHEMICAL SOC2020

Lead Halide Perovskite Quantum Dots to Enhance the Power Conversion Efficiency of Organic Solar Cells

Jun Ho Yum, Kevin Sivula, Florian Le Formal, Nestor Guijarro Carratala, Liang Yao, Barbara Alexandra Primera Darwich, Yongpeng Liu, Rebekah Anne Wells, Lucie Navratilova, Han-Hee Cho

The facile synthesis, solution-processability, and outstanding optoelectronic properties of emerging colloidal lead halide perovskite quantum dots (LHP QDs) makes them ideal candidates for scalable and inexpensive optoelectronic applications, including pho ...

Wiley-VCH Verlag GmbH2019

Robust Electron Transport Layers via In Situ Cross-Linking of Perylene Diimide and Fullerene for Perovskite Solar Cells

Sylvain Nicolay, Jun Ho Yum, Soo-Jin Moon, Kevin Sivula, Liang Yao, Marina Caroline Michèle Caretti

While employing charge transport layers (CTLs) in optoelectronic devices including hybrid perovskite solar cells is essential for high performance, using solution-processed organic semiconductor-based CTLs poses challenges for device fabrication. Cross-lin ...

2019

Nanocrystalline Boron-Doped Diamond as a Corrosion-Resistant Anode for Water Oxidation via Si Photoelectrodes

Ladislav Kavan, Jun Ho Yum, Kevin Sivula, Florian Le Formal, Petr Ashcheulov

Due to its high sensitivity to corrosion, the use of Si in direct photoelectrochemical (PEC) water-splitting systems that convert solar energy into chemical fuels has been greatly limited. Therefore, the development of low-cost materials resistant to corro ...

AMER CHEMICAL SOC2018

Multidimensional Anodized Titanium Foam Photoelectrode for Efficient Utilization of Photons in Mesoscopic Solar Cells

Jun Ho Yum

Mesoscopic solar cells based on nanostructured oxide semiconductors are considered as a promising candidates to replace conventional photovoltaics employing costly materials. However, their overall performances are below the sufficient level required for p ...

Wiley-V C H Verlag Gmbh2017

Iron Oxide Photoelectrode with Multidimensional Architecture for Highly Efficient Photoelectrochemical Water Splitting

Jun Ho Yum

Nanostructured metal oxide semiconductors have shown outstanding performances in photoelectrochemical (PEC) water splitting, but limitations in light harvesting and charge collection have necessitated further advances in photo-electrode design. Herein, we ...

Wiley-VCH Verlag GmbH2017

Pyridyl- and Picolinic Acid Substituted Zinc(II) Phthalocyanines for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Aravind Kumar Chandiran

A series of tri-tert-butyl zinc(II) phthalocyanines (Pcs) substituted with pyridyl, carboxyl, or picolinic acid anchoring groups on the periphery were prepared. Photovoltaic (PV) studies on these dyes were carried out revealing some interesting features. I ...

Wiley-VCH Verlag2017

The Many Faces of Mixed Ion Perovskites: Unraveling and Understanding the Crystallization Process

Mohammad Khaja Nazeeruddin, Jun Ho Yum, Kevin Sivula, Paul Gratia, Iwan Zimmermann

Understanding the crystallization process of organic-inorganic halide perovskites is of paramount importance for fabrication of reproducible and efficient perovskite solar cells. We report for the first time on the discovery and interplay of ubiquitous hex ...

Amer Chemical Soc2017

Inorganic p-Type Semiconductors: Their Applications and Progress in Dye-Sensitized Solar Cells and Perovskite Solar Cells

Peter Chen, Jun Ho Yum, Soo-Jin Moon, Meng Li

Considering the increasing global demand for energy and the harmful ecological impact of conventional energy sources, it is obvious that development of clean and renewable energy is a necessity. Since the Sun is our only external energy source, harnessing ...

MDPI2016

Organic-inorganic halide perovskite/crystalline silicon four-terminal tandem solar cells

Christophe Ballif, Sylvain Nicolay, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Julien Claude Bailat, Björn Niesen, Martin Ledinsky

Tandem solar cells constructed from a crystalline silicon (c-Si) bottom cell and a low-cost top cell offer a promising way to ensure long-term price reductions of photovoltaic modules. We present a four-terminal tandem solar cell consisting of a methyl amm ...

Royal Society of Chemistry2015

Complex Refractive Index Spectra of CH3NH3PbI3 Perovskite Thin Films Determined by Spectroscopic Ellipsometry and Spectrophotometry

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Michael Elias Stückelberger, Jérémie Werner, Björn Niesen

The complex refractive index (dielectric function) of planar CH3NH3PbI3 thin films at room temperature is investigated by variable angle spectroscopic ellipsometry and spectrophotometry. Knowledge of the complex refractive index is essential for designing ...

Amer Chemical Soc2015

Raman Spectroscopy of Organic-Inorganic Halide Perovskites

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Jakub Holovsky, Björn Niesen, Martin Ledinsky

Micro-Raman spectroscopy provides laterally resolved microstructural information for a broad range of materials. In this Letter, we apply this technique to tri-iodide (CH3NH3PbI3), tribromide (CH3NH3PbBr3), and mixed iodide-bromide (CH3NH3PbI3-xBrx) organi ...

Amer Chemical Soc2015

Laser-Scribing Patterning for the Production of Organometallic Halide Perovskite Solar Modules

Christophe Ballif, Laurent Fabien Hubert Sansonnens, Sylvain Nicolay, Jun Ho Yum, Soo-Jin Moon, Arnaud Walter, Mustapha Benkhaira, Julien Claude Bailat

Efficiencies of solar cells based on organometallic halide perovskite absorber material have dramatically increased over the past few years. Most of efficiencies reported so far have, however, been obtained on solar cells with very small lab-scale area of ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Diketopyrrolopyrole (dpp)-based sensitizers for electrochemical or optoelectronic devices

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Thomas Wesley Holcombe

The present invention relates to compounds of formula (I) based on DPP moiety being useful as metal-free organic sensitizers or dyes of type D-Pi-A in electrochemical or optoelectronic devices, their use as sensitizer or dye and an electrochemical or optoe ...

2015

Organic-Inorganic Halide Perovskites: Perspectives for Silicon-Based Tandem Solar Cells

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Franz-Josef Haug, Jakub Holovsky, Björn Niesen, Martin Ledinsky

We investigate the efficiency potential of organic-inorganic halide perovskite/crystalline silicon tandem solar cells, a new class of photovoltaic devices targeting long-term cost reductions by ultrahigh conversion efficiencies. Methyl ammonium lead triiod ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance

Christophe Ballif, Jun Ho Yum, Soo-Jin Moon, Stefaan De Wolf, Franz-Josef Haug, Jakub Holovsky, Björn Niesen, Martin Ledinsky

Solar cells based on organometallic halide perovskite absorber layers are emerging as a high-performance photovoltaic technology. Using highly sensitive photothermal deflection and photocurrent spectroscopy, we measure the absorption spectrum of CH3NH3PbI3 ...

Amer Chemical Soc2014

Panchromatic light harvesting by dye- and quantum dot-sensitized solar cells

Michael Graetzel, Robin Humphry-Baker, Jun Ho Yum, Yongjoo Kim

A PbS:Hg quantum dots-sensitized solar cell (QDSC) combined with a dye-sensitized solar cell (DSC) to harvest panchromatic solar spectrum from the visible light to the near IR is demonstrated. We use the filter to split the solar energy and access the tota ...

Pergamon-Elsevier Science Ltd2014

Redox couple for electrochemical and optoelectronic devices

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Jun Ho Yum, Aswani Yella, Hoi Nok Tsao

The present invention provides an improved redox couple for electrochemical and optoelectronic devices. The redox couple is based on a complex of a first row transition metal, said complex containing at least one mono-, bi-, or tridentate ligand comprising ...

2014

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