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Jun Ho Yum

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Publications associées (128)

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Nanofibrous TiO2 improving performance of mesoporous TiO2 electrode in dye-sensitized solar cell

Michael Graetzel, Jun Ho Yum, Ladislav Kavan

A method of direct coating of conducting glass by electrospinning was developed. Electrospun fibrous TiO2 consisting of closely packed anatase nanocrystals of 40-50 nm in size was incorporated into mesoporous TiO2 thin film stabilized by phosphorus. The me ...

Springer Verlag2013

The Role of p Bridges in High-Efficiency DSCs Based on Unsymmetrical Squaraines

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

A series of squaraine-based sensitizers with various p bridges and anchors were prepared and examined in dye-sensitized solar cells. The carboxylic anchor group was attached onto a squaraine dye through p bridges with and without an ethynyl spacer. DFT stu ...

Wiley-Blackwell2013

Sterically Hindered Phthalocyanines for Dye-Sensitized Solar Cells: Influence of the Distance between the Aromatic Core and the Anchoring Group

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

A new phthalocyanine (Pc) bearing bulky peripheral substituents and a carboxylic anchoring group directly attached to the macrocycle has been prepared and used as a sensitizer in DSSCs, reaching 5.57% power conversion efficiency. In addition, an enhanced p ...

Wiley-Blackwell2014

Di-branched di-anchoring organic dyes for dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

The first examples of di-branched di-anchoring organic sensitizers were synthesized and used in dye-sensitized solar cells leading to red-shifted IPCE maxima and increased photocurrent when compared to the corresponding mono-branched mono-anchoring dye, yi ...

2009

Methylammonium Nitrate-Mediated Crystal Growth and Defect Passivation in Lead Halide Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Kevin Sivula, Jun Ho Yum, Yeonju Kim

Additive engineering has been a crucial strategy to improve photovoltaic properties by reducing carrier trap centers or increasing carrier diffusion lengths in the lead halide perovskite active layer. We introduced a small amount of CH3NH3 +NO3 - (methylam ...

Amer Chemical Soc2024

Bis-Donor-Bis-Acceptor Tribranched Organic Sensitizers for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

A new class of tribranched dye-sensitized solar cell (DSC) sensitizers carrying two conjugated donors and two acceptor/anchoring groups is introduced. The approach leads to significantly different optical properties and enhanced stability with respect to r ...

Wiley-Blackwell2011

Structure-Function Relationships in Unsymmetrical Zinc Phthalocyanines for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

A series of unsymmetrical zinc phthalocyanines bearing an anchoring carboxylic function linked to the phthalocyanine ring through different spacers were designed for dye-sensitised solar cells (DSSC). The modification of the spacer group allows not only a ...

2009

A new familiy of heteroleptic ruthenium(II) polypyridyl complexes for sensitization of nanocrystalline TiO2 films

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Takeru Bessho

Two new heteroleptic ruthenium(II) photosensitizers that contains 2,2';6,2 ''-terpyridine with extended p-conjugation with donor groups, a 4,4'-dicarboxylic acid-2,2'-bipyridine anchoring ligand and a thiocyanate ligand have been designed, synthesized and ...

Royal Society of Chemistry2011

Panchromatic Response in Solid-State Dye-Sensitized Solar Cells Containing Phosphorescent Energy Relay Dyes

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Soo-Jin Moon

Running relay: Incorporating an energy-relay dye (ERD) into the hole transporter of a dye-sensitized solar cell increased power-conversion efficiency by 29 % by extending light harvesting into the blue region. In the operating mechanism (see picture), abso ...

Wiley-VCH Verlag GmbH2009

Panchromatic engineering for dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Sophie Wenger

The dye-sensitized mesoscopic solar cell has been intensively investigated as a promising photovoltaic cell. Its ecological and economical fabrication processes make it attractive and credible alternative to conventional photovoltaic systems. In contrast t ...

2011

Cyclometallated iridium complexes for conversion of light into electricity and electricity into light

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

This brief review describes applications of cyclometallated iridium complexes for energy saving organic light-emitting devices (OLED's) and energy generating molecular photovoltaic cells. The first part consists of a short overview of the methods to modula ...

2009

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

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

Carboxy-1,4-phenylenevinylene- and carboxy-2,6-naphthylene-vinylene unsymmetrical substituted zinc phthalocyanines for dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

Two unsymmetrical Zn(II) phthalocyanines 1 and 2 bearing an anchoring carboxylic function linked to the phthalocyanine ring through different rigid arylenevinylene bridges have been designed for dye-sensitized solar cell (DSSC) applications. The phthalocya ...

2009

High efficient donor-acceptor ruthenium complex for dye-sensitized solar cell applications

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Il Jung

A highly efficient heteroleptic ruthenium (II) complex cis-di(thiocyanato)(4,4'-dicarboxylic acid-2,2'-bipyridine)(4,4'-di-(2-(4-ditolylamine phenyl)ethenyl)-2,2'-bipyridine) ruthenium (II) (IJ-1) was synthesized and characterized, which when anchored on n ...

2009

Incorporating Multiple Energy Relay Dyes in Liquid Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Jun Ho Yum

Panchromatic response is essential to increase the light-harvesting efficiency in solar conversion systems. Herein we show increased light harvesting from using multiple energy relay dyes inside dye-sensitized solar cells. Additional photoresponse from 400 ...

2011

Peripherally and Axially Carboxylic Acid Substituted Subphthalocyanines for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Aswani Yella

A series of subphthalocyanines (SubPcs) bearing a carboxylic acid group either at the peripheral or axial position have been designed and synthesized to investigate the influence of the COOH group positions on the dye-sensitized solar cell (DSSC) performan ...

Wiley-Blackwell2014

Highly Efficient Solar Cells Using Organic Dyes with Amorphous Moiety

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum, Il Jung

Novel organic sensitizers comprising donor; electron-conducting, and anchoring groups were engineered at molecular level and synthesized. The functionalized unsymmetrical organic sensitizers 3-{5-[N,N-Bis(9,9-dimethylfluorene-2-yl)phenyl]-thiophene-2-yl}-2 ...

MRS2007

Increasing the efficiency of zinc-phthalocyanine based solar cells through modification of the anchoring ligand

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

Several zinc-based phthalocyanines have been synthesized and used in Dye-Sensitized Solar Cells (DSSC). The results have been compared with the standard TT1 phthalocyanine, which shows good light-to-energy conversion efficiencies in comparison with other I ...

2011

Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9%

Michael Graetzel, Robin Humphry-Baker, Jacques-Edouard Moser, Jun Ho Yum, Thomas Moehl, Soo-Jin Moon, Arianna Marchioro, Jeong-Hyeok Im

We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto ...

2012