권기환 교수

Two-dimensional ferroelectrics is attractive for synaptic device applications because of its low power consumption and amenability to high-density device integration. Here, we demonstrate that tin monosulfide (SnS) films less than 6 nm thick show optimum performance as a semiconductor channel in an in-plane ferroelectric analogue synaptic device, whereas thicker films have a much poorer ferroelectric response due to screening effects by a higher concentration of charge carriers. The SnS ferroele

Organolead halide perovskites (OHPs) have attracted extensive attention as light harvesting materials for solar cells recently, because of their high charge carrier mobility, high photoconversion efficiencies, low cost, and simple methodology. Despite these advantages, the OHPs exhibit sweep‐dependent hysteresis behavior in current–voltage characteristics films, deteriorating the reliability of devices based on the OHPs. This study demonstrates reliable high on/off ratio ( I on / I off = 10 4 )

A chemical approach was applied to decrease the work function of few-layer graphene. Li2CO3, K2CO3, Rb2CO3, and Cs2CO3 were used as n-doping materials. The sheet resistance of graphene doped with carbonate salt slightly increased from 1100 to 1700–2500 Ω/sq, and the transmittance of doped graphene with 0.1 M alkali metal at 550 nm decreased from 96.7 to 96.1–94% due to the formation of metal particles on the surface of graphene. A higher sheet resistance and lower transmittance were obtained at

PSS based devices. These results suggest that UV-O3-surface-treated MeS2 could be a promising candidate for a charge transport layer in optoelectronic devices.

In order to develop high performance chemoresistive gas sensors for Internet of Everything applications, low power consumption should be achieved due to the limited battery capacity of portable devices. One of the most efficient ways to reduce power consumption is to lower the operating temperature to room temperature. Herein, we report superior gas sensing properties of SnS₂ nanograins on SiO₂ nanorods toward NO₂ at room temperature. The gas response is as high

Abstract Single‐atom catalysts (SACs) have been garnering attention recently due to their excellent performance in significant catalytic reactions such as oxidation, water gas shift, and hydrogenation reactions. Unlike traditional nanocatalysts, the catalytic performance of SACs is highly dependent on the scale of catalysts, low‐coordination nature, and interaction between the catalysts and support materials. The size of metal particles is a key factor in determining the performance of the catal

Efficient photoelectrochemical hydrogen production is demonstrated by sulphur-doped molybdenum phosphide/p-Si heterojunctions.

Green hydrogen is being considered as a next-generation sustainable energy source. It is created electrochemically by water splitting with renewable electricity such as wind, geothermal, solar, and hydropower. The development of electrocatalysts is crucial for the practical production of green hydrogen in order to achieve highly efficient water-splitting systems. Due to its advantages of being environmentally friendly, economically advantageous, and scalable for practical application, electrodep

Developing cost-effective, highly catalytic active, and stable electrocatalysts in alkaline electrolytes is important for the development of highly efficient anion-exchange membrane water electrolysis (AEMWE). To this end, metal oxides/hydroxides have attracted wide research interest for efficient electrocatalysts in water splitting owing to their abundance and tunable electronic properties. It is very challenging to achieve an efficient overall catalytic performance based on single metal oxide/

The doping mechanism of graphene with chlorides of low work-function metals was investigated using NaCl, KCl, MgCl2, and CaCl2. After graphene was doped with 1.0 M dopants, the sheet resistance of the graphene increased from 780 Ω sq–1 to 1350–1620 Ω sq–1 after doping. Its transmittance at 550 nm also decreased from 97% to 90–94% owing to the presence of metal particles. The shift of G and 2D peaks in the Raman spectra coincided with n-type doping phenomena. The shift of the peak for the C═C bon

Two-dimensional (2D) materials have emerged as a promising candidate in the chemoresistive gas sensor field to overcome the disadvantages of conventional metal-oxide semiconductors owing to their strong surface activities and high surface-to-volume ratio. This review summarizes the various approaches to enhance the 2D-material-based gas sensors and provides an overview of their progress. The distinctive attributes of semiconductor gas sensors employing 2D materials will be highlighted with their

The degradation mechanism of graphene sheets doped with metal chloride was investigated as a function of the annealing process. The sheet resistance of doped graphene increased from 500–700 Ω sq−1 to 10 kΩ sq−1 and the transmittance at 550 nm decreased from 95% to 87–91% after annealing at 400 °C. Furthermore, the work function of doped graphene decreased from 4.7–5.1 eV to 4.2–4.5 eV after annealing. The G and 2D band peaks in the Raman spectra were shifted to lower wavenumbers by annealing at