Yoonsoo Rho

Various exotic optoelectronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs) strongly depend on their number of layers, and typically manifest in ultrathin few-layer or monolayer formats. Thus, precise manipulation of thickness and shape is essential to fully access their potential in optoelectronic applications. Here, we demonstrate site-selective atomic layer precision thinning of exfoliated MoS₂ flake by laser. The oxidation mediated anisotropic chemica

In this study, we perform drop-on-demand (DOD) inkjet printing and laser reductive sintering of precrystallized NiO nanoparticle (NP) ink under ambient conditions to obtain NiO/Ni hybrid electrode patterns on a highly localized area. By formulating an inkjet-printable and laser-reducible NiO NP ink, and by exploring the optimum conditions of inkjet printing parameters, we generate stable droplets, enabling arbitrary shapes of NiO NP dot arrays or line patterns to be deposited. Subsequent short-t

Carrier distribution and dynamics in semiconductor materials often govern their physical properties that are critical to functionalities and performance in industrial applications. The continued miniaturization of electronic and photonic devices calls for tools to probe carrier behavior in semiconductors simultaneously at the picosecond time and nanometer length scales. Here, we report pump-probe optical nanoscopy in the visible-near-infrared spectral region to characterize the carrier dynamics

Abstract The effect of various materials of the spherical scattering centre in a TiO 2 nanoporous structure in dye-sensitized solar cells (DSSCs) was investigated by both theoretical simulation and experiment. Three materials, titania, electrolyte and silica, were investigated using the Mie Theory, in which the concepts of volume total cross section and solar spectrum were accommodated for better accuracy. Of those materials, silica was chosen in this study due to its perfectly transparent natur

Biological nervous systems rely on the coordination of billions of neurons with complex, dynamic connectivity to enable the ability to process information and form memories. In turn, artificial intelligence and neuromorphic computing platforms have sought to mimic biological cognition through software-based neural networks and hardware demonstrations utilizing memristive circuitry with fixed dynamics. To incorporate the advantages of tunable dynamic software implementations of neural networks in

We describe a wide-field approach to probe transient changes in photoluminescence (PL) of defects on silica surfaces. This technique allows simultaneous capture of spatially resolved PL with spontaneous quenching behavior. We attribute the quenching of PL intensity to photochemical reactions of surface defects and/or subsurface fractures with ambient molecules. Such quenching curves can be accurately reproduced by our theoretical model using two quenchable defect populations with different react

Nonlinear optical response is a fingerprint of various physicochemical properties of materials related to symmetry, including crystallography, interfacial configuration, and carrier dynamics. However, the intrinsically weak nonlinear optical susceptibility and the diffraction limit of far-field optics restrict probing deep-subwavelength-scale nonlinear optics with measurable signal-to-noise ratio. Here, we propose an alternative approach toward efficient second harmonic generation (SHG) nanoscop

Abstract A key feature of 2D transition metal dichalcogenides (2D‐TMDCs) is that their properties are strongly dependent on their thickness, typically appearing in ultrathin mono‐ or few‐ layers. Thus, precise control of functional nanostructure is critical for fundamental research and applications in 2D‐TMDCs. Here, atomic layer precision thinning of molybdenum ditelluride (MoTe 2 ) at nanoscale lateral resolution by introducing laser irradiated hot tip is demonstrated. The contact of the hot t

We use photoluminescence (PL) imaging to study damage growth precursors within laser damage sites on the surface of silica. Damage site evolution is induced by multiple shots of UV nanosecond pulsed laser at various energy densities and monitored throughout the early stages of growth. Wide-field PL imaging rapidly locates microscopic light absorption centers within the silica damage site. Our quantitative analysis shows that damage sites with strong local PL intensity show a higher probability o

Transition metal dichalcogenides (TMDCs) have shown exceptional optoelectronic properties that can potentially substitute conventional silicon-based devices and be utilized in sensors and energy devices. To exploit their wide array of potential applications, it is necessary to develop methods capable of on demand, location selective, and tunable formation of structures of arbitrary shape. Here, we demonstrated high-speed direct writing of MoSe2 by laser-induced selenization process in vacuum or

Source Data supporting the plots within the paper "A laser-assisted chlorination process for reversible writing of doping patterns in graphene." Including Source Data for Figures 1-4 in the main text, and Supplementary Figures S1, S3-12, S14, S17.

Source Data supporting the plots within the paper "A laser-assisted chlorination process for reversible writing of doping patterns in graphene." Including Source Data for Figures 1-4 in the main text, and Supplementary Figures S1, S3-12, S14, S17.