Publications de Jun Ho Yum | EPFL Graph Search

Unexpected Pathway in Organic Semiconductor Nanoparticle Formation

Jun Ho Yum, Kevin Sivula, Arthur Eliot Bouchez

Organic semiconductor (OSC) nanoparticles (NPs) are promising for numerous applications including greener organic photovoltaics and heterogeneous photocatalysts for solar H2 production. Single component or mixed bulk-heterojunction (BHJ) OSC NPs are common ...

AMER CHEMICAL SOC2025

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

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

Interfacial engineering through lead binding using crown ethers in perovskite solar cells

Jun Ho Yum, Kevin Sivula, Jiyoun Seo, Jovana Milic, Yeonju Kim

In the domain of perovskite solar cells (PSCs), the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative solutions. This study pioneers an approach that not only rectifies lea ...

Elsevier2024

Decoupling Interlayer Spacing and Cation Dipole on Exciton Binding Energy in Layered Halide Perovskites

Rosario Scopelliti, Nicolas Grandjean, Jun Ho Yum, Kevin Sivula, Simon Nussbaum, Han-Hee Cho, Yeonju Kim

Layered halide perovskites (LHPs) are emerging semiconductor materials due to their superior environmental stability compared to that of traditional halide perovskites. While LHPs have tunable optoelectronic properties, quantum and dielectric confinement e ...

2024

Free Charge Carrier Generation by Visible-Light-Absorbing Organic Spacers in Ruddlesden-Popper Layered Perovskites

Jacques-Edouard Moser, Jun Ho Yum, Kevin Sivula, Natalie Renuka Banerji, Aaron Tomas Terpstra, Simon Nussbaum

Incorporating organic semiconductor building blocks as spacer cations into layered hybrid perovskites provides an opportunity to develop new materials with novel optoelectronic properties, including nanoheterojunctions that afford spatial separation of ele ...

2024

Supramolecular interactions using β-cyclodextrin in controlling perovskite solar cell performance

Jun Ho Yum, Kevin Sivula, Jiyoun Seo, Parnian Ferdowsi

In the context of perovskite solar cells (PSCs), enhancing device performance often involves adding a small excess of lead iodide (PbI2) to the precursor solution. However, the presence of unreacted PbI2 can lead to accelerated degradation compromising lon ...

Royal Society of Chemistry2024

Surface Passivation of FAPbI3-Rich Perovskite with Cesium Iodide Outperforms Bulk Incorporation

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Mounir Driss Mensi, Jun Ho Yum, Kevin Sivula, Thomas Paul Baumeler, Essa Awadh R Alharbi, Brian Irving Carlsen, Jing Gao, George Cameron Fish, Felix Thomas Eickemeyer, Lukas Pfeifer, Georgios Kakavelakis

Metal halide perovskites (MHPs) have shown an incredible increase in efficiency, reaching as high as 25.7%, which now competes with traditional photovoltaic technologies. Herein, we excluded CsX and RbX (X = I–, Br–, Cl–), the most commonly used cations to ...

2023

Bifunctional hole-shuttle molecule for improved interfacial energy level alignment and defect passivation in perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jun Ho Yum, Kevin Sivula, Dan Ren, Jing Gao, Meng Xia, Felix Thomas Eickemeyer, Zhongjin Shen

Interface engineering in perovskite solar cells is key to high performance. Now, You et al. design an interlayer that both passivates defects and improves the energy level alignment between the perovskite and hole transport material. ...

NATURE PORTFOLIO2023

Photogenerated charge transfer in Dion-Jacobson type layered perovskite based on naphthalene diimide

Jacques-Edouard Moser, Jun Ho Yum, Kevin Sivula, Etienne Christophe Socie, Simon Nussbaum, George Cameron Fish

Incorporating organic semiconducting spacer cations into layered lead halide perovskite structures provides a powerful approach to mitigate the typical strong dielectric and quantum confinement effects by inducing charge-transfer between the organic and in ...

2023

Understanding and Mitigating the Degradation of Perovskite Solar Cells Based on a Nickel Oxide Hole Transport Material during Damp Heat Testing

Christophe Ballif, Mounir Driss Mensi, Jun Ho Yum, Kevin Sivula, Yongpeng Liu, Marion Solange Madeleine Dussouillez, Christian Michael Wolff

The development of stable materials, processable on alarge area,is a prerequisite for perovskite industrialization. Beyond the perovskiteabsorber itself, this should also guide the development of all otherlayers in the solar cell. In this regard, the use o ...

AMER CHEMICAL SOC2023

Transparent Porous Conductive Substrates for Gas-Phase Photoelectrochemical Hydrogen Production

Jun Ho Yum, Kevin Sivula, Linda Lazouni, Loï Charles Carbone, Benjamin Goldman, Rebekah Anne Wells, Simon Nussbaum, Marina Caroline Michèle Caretti, Elizaveta Potapova Mensi, Hannah Elizabeth Johnson, Emeline Cécile Rideau

Gas diffusion electrodes are essential components of common fuel and electrolysis cells but are typically made from graphitic carbon or metallic materials, which do not allow light transmittance and thus limit the development of gas-phase based photoelectr ...

Wiley-V C H Verlag Gmbh2023

Ink-Based CuIn0.3Ga0.7S2 Nanocrystal Thin Films as Photocathodes for Photoelectrochemical CO2 Reduction Reaction

Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala

One of the promising methods to solve the current energyand environmentissues is photoelectrochemical (PEC) water splitting and CO2 reduction reaction. Chalcopyrite copper indium gallium sulfide (CIGS)and CuIn0.3Ga0.7S2 nanocrystal thinfilms have been cons ...

AMER CHEMICAL SOC2023

Photoelectrochemical CO2 Reduction at a Direct CuInGaS2/Electrolyte Junction

Michael Graetzel, Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Yongpeng Liu, Simon Nussbaum, Dan Ren, Meng Xia

Photoelectrochemical (PEC) CO2 reduction has received considerable attention given the inherent sustainability and simplicity of directly converting solar energy into carbonbased chemical fuels. However, complex photocathode architectures with protecting l ...

AMER CHEMICAL SOC2023

Benzodithiophene derivative 2D spacer as a defect passivation material in metal halide perovskite solar cells

Jun Ho Yum

Defect passivation is an efficient strategy for improving the performance of perovskite solar cells (PSCs). In this study, we introduced a benzodithiophene-based 2D spacer with a short alkyl chain (BDT-C2) into a perovskite film for defect passivation. The ...

KOREAN PHYSICAL SOC2023

An Organic Semiconductor Photoelectrochemical Tandem Cell for Solar Water Splitting

Mounir Driss Mensi, Jun Ho Yum, Kevin Sivula, Han-Hee Cho, Dan Zhang

Photoelectrochemical cells employing organic semiconductors (OS) are promising for solar-to-fuel conversion via water splitting. However, despite encouraging advances with the half reactions, complete overall water splitting remains a challenge. Herein, a ...

WILEY-V C H VERLAG GMBH2022

Tuning Napththalenediimide Cations for Incorporation into Ruddlesden–Popper-Type Hybrid Perovskites

Jacques-Edouard Moser, Jun Ho Yum, Kevin Sivula, Etienne Christophe Socie, Liang Yao, Simon Nussbaum

Layered hybrid organic−inorganic perovskite (LHOIP) materials constructed with low-band-gap chromophore-based organic spacer cations are anemerging class of materials that promise unique tunability of their optoelectronic properties. However, the large siz ...

2022

Bulk Heterojunction Organic Semiconductor Photoanodes: Tuning Energy Levels to Optimize Electron Injection

Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Barbara Alexandra Primera Darwich, Yongpeng Liu, Han-Hee Cho, Juan Manuel Moreno Naranjo

The use of a bulk heterojunction of organic semiconductors to drive photoelectrochemical water splitting is an emerging trend; however, the optimum energy levels of the donor and acceptor have not been established for photoanode operation with respect to e ...

AMER CHEMICAL SOC2022

Benzodithiophene‐Based Spacers for Layered and Quasi‐Layered Lead Halide Perovskite Solar Cells

Mounir Driss Mensi, Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Luc Emile Monnier, Liang Yao, Barbara Alexandra Primera Darwich, Han-Hee Cho

Incorporating extended pi-conjugated organic cations in layered lead halide perovskites is a recent trend promising to merge the fields of organic semiconductors and lead halide perovskites. Herein, we integrate benzodithiophene (BDT) into Ruddlesden–Poppe ...

2021

A semiconducting polymer bulk heterojunction photoanode for solar water oxidation

Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Yongpeng Liu, Rebekah Anne Wells, Florent Alexandre Boudoire, Han-Hee Cho

Organic semiconductors hold promise to enable scalable, low-cost and high-performance artificial photosynthesis. However, the performance of systems based on organic semiconductors for light-driven water oxidation have remained poor compared with inorganic ...

NATURE RESEARCH2021

A hybrid bulk-heterojunction photoanode for direct solar-to-chemical conversion dagger

Michael Graetzel, Jun Ho Yum, Kevin Sivula, Nestor Guijarro Carratala, Arvindh Sekar, Liang Yao, Barbara Alexandra Primera Darwich, Yongpeng Liu, Rebekah Anne Wells, Dan Ren, Han-Hee Cho, Meng Xia

Organic semiconductors (OSs) are emerging candidates as light-harvesting materials in photoelectrochemical (PEC) cells for direct solar-to-chemical conversion. Despite significant recent progress with OS-based photocathodes, the development of efficient an ...

ROYAL SOC CHEMISTRY2021