Publications by Hui-Seon Kim | EPFL Graph Search

Surface Reconstruction Engineering with Synergistic Effect of Mixed‐Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Filippo de Angelis, Hui-Seon Kim, Bowen Yang, Jiajia Suo, Yeonju Kim

Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well a ...

2021

Dopant Engineering for Spiro‐OMeTAD Hole‐Transporting Materials towards Efficient Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jovana Milic, Jiyoun Seo, Hui-Seon Kim, Seckin Akin, Marco Alejandro Ruiz Preciado

One of the most prominent hole-transporting material (HTM) for hybrid perovskite solar cells has been 2,2″,7,7″-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD), which is commonly doped with metal bis(trifluoromethylsulfonyl)imide ...

2021

Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Ulf Anders Hagfeldt, Dominik Józef Kubicki, Zaiwei Wang, Hui-Seon Kim, Anand Agarwalla

Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic ...

CELL PRESS2021

Outstanding Passivation Effect by a Mixed-Salt Interlayer with Internal Interactions in Perovskite Solar Cells

Ulf Anders Hagfeldt, Wolfgang Richard Tress, Bowen Yang, Filippo de Angelis, Jiajia Suo, Hui-Seon Kim

Nonradiative recombination is a major limiting factor in obtaining efficient metal-halide perovskite photovoltaics. Here, a passivation treatment is developed by applying a mixture of a new ammonium salt, CF3(CF2)(2)CH2NH3I (HBAI), and a conventional forma ...

AMER CHEMICAL SOC2020

Liquid State and Zombie Dye Sensitized Solar Cells with Copper Bipyridine Complexes Functionalized with Alkoxy Groups

Michael Graetzel, Shaik Mohammed Zakeeruddin, Rosario Scopelliti, Jacques-Edouard Moser, Ulf Anders Hagfeldt, Joël Teuscher, Yasemin Saygili, Marina Freitag, Hui-Seon Kim, Marko Stojanovic

Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolytes or as solid state hole transport materials (HTMs). The solid state devices that employ copper complex HTMs can be simply obtained by solvent evaporation ...

2020

Revealing the Mechanism of Doping of spiro-MeOTAD via Zn Complexation in the Absence of Oxygen and Light

Ulf Anders Hagfeldt, Yasemin Saygili, Hui-Seon Kim, Bowen Yang, Jiajia Suo

In this study, a new mechanism for doping of spiro-MeOTAD by Zn(TFSI)(2) is revealed, which is completely different from the mechanism induced by LiTFSI. The oxidation of spiro-MeOTAD is facilitated by complexation between the zinc cation and tert-butylpyr ...

AMER CHEMICAL SOC2020

Bifunctional Organic Spacers for Formamidinium-Based Hybrid Dion-Jacobson Two-Dimensional Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jovana Milic, Ulf Anders Hagfeldt, Mohammad Ibrahim Dar, Peng Wang, Yuhang Liu, Jiyoun Seo, Amita Ummadisingu, Yang Li

Three-dimensional (3D) perovskite materials display remarkable potential in photovoltaics owing to their superior solar-to-electric power conversion efficiency, with current efforts focused on improving stability. Two-dimensional (2D) perovskite analogues ...

AMER CHEMICAL SOC2019

PbZrTiO3 ferroelectric oxide as an electron extraction material for stable halide perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Michael Saliba, Silver Hamill Turren Cruz, Zaiwei Wang, Hui-Seon Kim, Monica Marcela Lira Cantu, Haibing Xie, Anna Morales Melgares

State-of-the-art halide perovskite solar cells employ semiconductor oxides as electron transportmaterials. Defects in these oxides, such as oxygen vacancies (Ovac), act as recombination centres and, in air and UV light, reduce the stability of the solar ce ...

2019

Power output stabilizing feature in perovskite solar cells at operating condition: Selective contact-dependent charge recombination dynamics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Jiyoun Seo, Hui-Seon Kim, Seckin Akin

Stabilized power output at maximum power point (mpp) has been considered as one of the most reliable parameters as it provides a key performance indicator for perovskite solar cells (PSCs) revealing the operational stability of the photovoltaic device. Her ...

Elsevier Science Bv2019

Photoinduced Lattice Symmetry Enhancement in Mixed Hybrid Perovskites and Its Beneficial Effect on the Recombination Behavior

Ulf Anders Hagfeldt, Hui-Seon Kim

The strategy of mixing cations and halides in hybrid organic lead halide perovskites has recently been shown to be very successful in achieving high efficiency with long-term perovskite solar cell stability. In this study, the effect of photoexcitation on ...

WILEY-V C H VERLAG GMBH2019