Donghwa Lee 교수

Ferroelectric $180\ifmmode^\circ\else\textdegree\fi{}$ domain walls are well-known to be predominantly Ising-like. Using density functional theory, and molecular dynamics simulations, the $180\ifmmode^\circ\else\textdegree\fi{}$ domain walls in prototypical ferroelectrics lead titanate $({\text{PbTiO}}_{3})$ and lithium niobate $({\text{LiNbO}}_{3})$ are shown to have mixed character; while predominantly Ising-like, they also manifest some Bloch- and N\'eel-like character. Phase-field calculatio

As silicon-based metal oxide semiconductor field effect transistors get closer to their scaling limit, the importance of resistive random-access memory devices increases due to their low power consumption, high endurance and retention performance, scalability, and fast switching speed. In the last couple of years, organic-inorganic lead halide perovskites have been used for resistive switching applications, where they outperformed conventional metal oxides in terms of large on/off ratio and low

Abstract Organic–inorganic halide perovskite is regarded as one of the potential candidates for next generation resistive switching memory (memristor) material because of fast, millivolt‐scale switching, multilevel capability, and high On/Off ratio. Here, resistive switching property of HC(NH 2 ) 2 PbI 3 (FAPbI 3 ) depending on structural phase is reported. It is found that 1D hexagonal FAPbI 3 (δ‐FAPbI 3 ), formed at relatively low temperature, is active in memristor, while 3D trigonal FAPbI3 (

Detection of ppb level ammonia at room temperature is demonstrated using chemically fluorinated graphene oxide (CFGO). Fluorine adatom extremely enhances ammonia sensing capabilities through the changes of the charge distributions on adjacent functional groups, resulting in the variation in gas adsorption energies.

All-inorganic cesium lead triiodide (CsPbI₃ ) perovskite is considered a promising solution-processable semiconductor for highly stable optoelectronic and photovoltaic applications. However, despite its excellent optoelectronic properties, the phase instability of CsPbI₃ poses a critical hurdle for practical application. In this study, a novel stain-mediated phase stabilization strategy is demonstrated to significantly enhance the phase stability of cubic α-phase CsPbI<sub>

Metal to semiconductor transition by hole compensation of excess electrons from <italic>V</italic>_O and localized <italic>V</italic>_O state in La_0.5Sr_0.5FeO_3−δ under low <italic>P</italic>_O2.

Atomistic simulations with empirical potentials and density-functional theory calculations are used to characterize the structure, energetics, and ferroelectric properties of domain walls in ${\text{LiNbO}}_{3}$. The two methods yield similar polarization patterns and atomic structures at the domain walls. The structure of the domain wall on the mixed anion-cation planes is very different from that of the domain wall on planes of alternating cations and anions. The breaking of the uniaxial symme

Graphene is one of the most promising materials for high-performance gas sensors due to its unique properties such as high sensitivity at room temperature, transparency, and flexibility. However, the low selectivity and irreversible behavior of graphene-based gas sensors are major problems. Here, we present unprecedented room temperature hydrogen detection by Au nanoclusters supported on self-activated graphene. Compared to pristine graphene sensors, the Au-decorated graphene sensors exhibit hig

Effective methods for decoupling superconducting qubits (SQs) from parasitic environmental noise sources are critical for increasing their lifetime and phase fidelity. While considerable progress has been made in this area, the microscopic origin of noise remains largely unknown. In this work, first principles density functional theory calculations are employed to identify the microscopic origins of magnetic noise sources in SQs on an α-Al2O3 substrate. The results indicate that it is unlikely t

Photocatalytic reduction of carbon dioxide (CO(2)) into hydrocarbons is an attractive approach for mitigating CO(2) emission and generating useful fuels at the same time. Titania (TiO(2)) is one of the most promising photocatalysts for this purpose, and nanostructured TiO(2) materials often lead to an increased efficiency for the photocatalytic reactions. However, what aspects of and how such nanomaterials play the important role in the improved efficiency are yet to be understood. Using first-p