Jiwon Kim

Abstract Cesium‐based perovskite nanocrystals (NCs) have outstanding photophysical properties improving the performances of lighting devices. Fundamental studies on excitonic properties and hot‐carrier dynamics in perovskite NCs further suggest that these materials show higher efficiencies compared to the bulk form of perovskites. However, the relaxation rates and pathways of hot‐carriers are still being elucidated. By using ultrafast transient spectroscopy and calculating electronic band struct

Abstract Direct partial oxidation of methane to liquid oxygenates has been regarded as a potential route to valorize methane. However, CH 4 activation usually requires a high temperature and pressure, which lowers the feasibility of the reaction. Here, we propose an electro-assisted approach for the partial oxidation of methane, using in-situ cathodically generated reactive oxygen species, at ambient temperature and pressure. Upon using acid-treated carbon as the electrocatalyst, the electro-ass

A novel strategy to prepare organometallic halide perovskite quantum dots (OHP-QDs) in a polymer film can enhance both the structural stability and the optical properties.

Abstract Cesium‐based perovskite nanocrystals (NCs) have outstanding photophysical properties improving the performances of lighting devices. Fundamental studies on excitonic properties and hot‐carrier dynamics in perovskite NCs further suggest that these materials show higher efficiencies compared to the bulk form of perovskites. However, the relaxation rates and pathways of hot‐carriers are still being elucidated. By using ultrafast transient spectroscopy and calculating electronic band struct

Although Group II-VI quantum dots (QDs) have attracted much attention due to their wide range of applications in QD-based devices, the presence of toxic ions in II-VI QDs raises environmental concerns. To fulfill the demands of nontoxic QDs, synthetic routes for III-V QDs have been developed. However, only a few comparative analyses on optical properties of III-V QDs have been performed. In this study, the composition-related energetic trap distributions have been explored by using three differe

Using ultrafast transient absorption spectroscopy, we investigated the surface carrier trapping dynamics in various sized PbS quantum dots (QDs) when either a hot or cold exciton is photogenerated by different pump-energy. We observed that hot carriers exhibit distinctly different surface trapping dynamics from the cold exciton, in which their corresponding transient absorption (TA) spectral evolutions show clear differences in the long wavelength region (less than a band gap energy, E g ). We o

Mesoporous carbon derived from pyrolysis of metal–organic frameworks (MOFs) is advantageous owing to its high specific surface area, large pore volume, and versatility in both structure and composition. Heteroatom doping on mesoporous carbon by synthesizing with heteroatom containing ligands (pre-synthetic process) or incorporating heteroatom-containing compounds during pyrolysis (post-doping) can further enhance its electrochemical properties. Although both methods have been applied to increase

Nanographenes, finite models of graphene sheets, are endowed with intriguing optical, electronic, and spintronic features. So-called heteroatom-doping, where one or more carbon is replaced by non-carbon light atoms has been proved effective in tuning the properties of nanographenes. Here we extend the concept of heteroatom nanographene doping to include metal centers. The method employed involves the use of a dipyrromethene fragment as an auxiliary ligand that is directly linked to the bay area

Abstract Nitrogen‐doped porous carbon derived from various polymer precursors receives great attention for applications in supercapacitor electrodes due to its high specific area and fast ion transportation within the electrodes. The porous structure with high content of nitrogen atoms enhances the wettability and accelerates the diffusion of ions inside free‐standing electrodes. These electrodes are fabricated by carbonization of nitrogen‐rich carbon precursors such as polyimide and polyaniline