A5058682088- ZnO doping and properties
- Perovskite Materials and Applications
- Semiconductor materials and devices
- GaN-based semiconductor devices and materials
- Organic Light-Emitting Diodes Research
- Conducting polymers and applications
- Gas Sensing Nanomaterials and Sensors
- Ga2O3 and related materials
- Quantum Dots Synthesis And Properties
- Advanced Sensor and Energy Harvesting Materials
- Nanowire Synthesis and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Thin-Film Transistor Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Metal and Thin Film Mechanics
- Electronic and Structural Properties of Oxides
- Organic Electronics and Photovoltaics
- Nanomaterials and Printing Technologies
- Transition Metal Oxide Nanomaterials
- Nanofabrication and Lithography Techniques
- Machine Learning in Materials Science
- Photonic and Optical Devices
- Chalcogenide Semiconductor Thin Films
- Advanced biosensing and bioanalysis techniques
- Copper-based nanomaterials and applications
Yonsei University
2015-2025
Seoul Institute
2017-2018
Government of the Republic of Korea
2017-2018
University of Illinois Urbana-Champaign
1996-2001
Material Sciences (United States)
1996
The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show process Mo1-xWxS2 using sulfurization super-cycle atomic layer deposition Mo1-xWxOy. Various spectroscopic microscopic results indicate that the synthesized alloys have complete mixing Mo W atoms gap by systematically controlled composition number. Based this, synthesize vertically...
Abstract Electrochromic materials reversibly change colors by redox reactions depending on the oxidation states. To utilize electrochromic for active‐matrix display applications, an (ECD) requires simultaneous implementation of various and a fine‐pixelation process. Herein, flexible transparent ECDs with simultaneously implementable subpixelated EC gels sequential multiple patterning are successfully demonstrated. Ionic liquid‐based monoheptyl‐viologen, diheptyl‐viologen (DHV),...
Sub-10 nm Graphene Nanoribbon Arrays are fabricated over large areas by etching CVD-grown graphene. A mask is used made the directed self-assembly of a cylindrical PS-b-PDMS block copolymer under solvent annealing guided removable template. The optimized process, surface-modified polymeric templates, and high Flory-Huggins interaction parameters enable highly aligned array nanoribbons with low line edge roughness to be formed. This leads higher on/off ratio stronger temperature dependence...
Vertically aligned ZnO nanowires were grown on c-plane sapphire substrate by metal organic chemical vapor deposition technique. The single crystalline and structurally uniform did not exhibit any noticeable defects. Pt/ZnO nanowire Schottky diodes fabricated using e-beam lithography then characterized measuring temperature-dependent I−V characteristics. diode exhibited a low barrier height of 0.42 V ideality factor 1.6 at room temperature. Temperature-dependent hydrogen-sensing measurements...
Out of the blue: Light-emitting diodes were obtained by fabricating p+-GaN film/n-ZnO nanowire array/n+-ZnO film structures (see figure). Blue electroluminescence (EL) emission was observed from nanowire-inserted heterojunction under forward bias. These exhibited improved EL and injection current compared to those film-based diodes.
A thermochromic-based interactive sensor that can generate local color switching and pressure mapping is developed using a 2D array of resistive switch. This will enable the visualization localized information in arbitrary shapes with dynamic responses context serial/parallel quantifying capability without optoelectronic arrays.
Abstract Due to the increasing interest in wearable devices, flexible and stretchable film heaters have been widely studied, as alternatives with conventional rigid shapes. Herein, a highly heater (SFH) based on silver nanowire (Ag NW)–single‐walled carbon nanotube composite thermochromic display polydimethylsiloxane (PDMS) substrate is successfully fabricated. The SFH shows excellent electrical conductivity, high mechanical stretchability, outstanding reliability, no significant degradation...
Abstract For resolving toxicity issues of Pb‐based perovskites, Sn‐based perovskites have been widely studied as a promising alternative due to similar valence electron configuration between Sn 2+ and Pb . However, desired in the precursor solution film is easily oxidized 4+ , causing detrimental vacancies impurities films. Unfortunately, dimethyl sulfoxide, ubiquitously used Lewis base for fabrication high‐quality perovskite thin films via adduct approach, further accelerates oxidation...
Abstract Perovskite light‐emitting diodes (PeLEDs) have garnered considerable interest in recent years owing to their unique optoelectronic properties. However, the performance of PeLEDs is limited by low quantum efficiency and unbalanced charge injection. In this study, address these issues, a novel co‐hole transport layer (HTL) 4,4′‐bis( N ‐carbazolyl)‐1,1′‐biphenyl (CBP) poly(9‐vinylcarbazole) (PVK) introduced into PeLEDs. By optimizing composition ratio CBP PVK, CsPbBr 3 ‐based...
Abstract Blue emissive perovskites can be prepared by incorporating chlorine into bromine‐based to tune their bandgap. However, mixed‐halide exhibit intrinsic phase instability, particularly under electrical potential, owing halide migration. To achieve high‐performance blue perovskite‐based light‐emitting diodes (PeLEDs) with operational stability, organic ammonium cations are used for passivating the anionic defects of CsPbBr 2 Cl film. Diphenylpropylammonium chloride (DPPACl), as a agent,...
Abstract Photolithography is the prevalent microfabrication technology. It needs to meet resolution and yield demands at a cost that makes it economically viable. However, conventional far-field photolithography has reached diffraction limit, which imposes complex optics short-wavelength beam source achieve high expense of efficiency. Here, we present cost-effective near-field optical printing approach uses metal patterns embedded in flexible elastomer photomask with mechanical robustness....
Tactile sensors are being researched as a key technology for developing an electronic skin and wearable display, which have recently been attracting much attention. However, to develop next-generation tactile sensor, it is necessary implement interactive display that responds immediately external stimuli. Herein, semitransparent pressure-sensitive light-emitting sensor (PLS) based on electrochemiluminescence (ECL) successfully implemented with visual alarm functions prevent damage the human...
Halide perovskites have potential for use in next-generation low-cost, high-efficiency, and highly color-pure light-emitting diodes (LED) that can be used various applications, such as flat flexible displays solid-state lighting. However, they still lag behind other mature technologies, organic LEDs inorganic LEDs, terms of performance, particularly brightness. This is partly due to the insulating nature long-chain ligands control perovskite-film morphology. Herein, a...
Synchrotron x-ray diffraction was employed to measure the lattice constants a and c of GaN films grown with an AlN buffer layer on sapphire (0001) over thickness range 50 Å 1 μm. We used multiple reflections least-squares fit method for high reliability. As increased, constant increased from 3.133 3.196 decreased 5.226 5.183 Å. The expected trend fitted equilibrium theory, allowing critical be estimated at 29 ± 4 in good agreement theoretical prediction.
As the lighting technology evolves, need for violet light-emitting diodes (LEDs) is growing high color rendering index lighting. The present LEDs based on high-cost GaN materials and metal-organic chemical vapor deposition process; therefore, there have recently been intensive studies developing low-cost alternative processes. In this study, first time, we demonstrated processes using a p-CuI thin film/n-MgZnO quantum dot (QD) heterojunction. film layer was prepared by an iodination process...
Translucent Au/graphene hybrid films are shown to be effective in reducing thermal emission from the underlying surfaces when deposition thickness of Au is close percolation threshold. The critical for an abrupt change emissivity reduced 15 nm (Si substrate) a percolation-threshold-limited 8.5 (graphene/Si because chemical inertness graphene leading deposited atoms forming thin, crystalline layer. effect layer on optical properties film highlighted by drastic increase infrared absorptivity,...
Elucidation of the key mechanism inactive Pt catalyst for hydrogen production in alkaline media and description two control factors catalytic activity a pseudo-binary Pt–M catalyst.
A hybrid electrode, PEDOT:PSS/Ag NW containing a non-ionic surfactant (Triton X-100), was developed to enhance the mechanical stability of Ag electrode and used for flexible ECL displays. The resulting exhibited an outstanding figure merit value 12.3 × 10-3 Ω-1 stable luminescence efficiency under bending test.
The morphology, crystal size, and trap density of perovskite films significantly affect the luminescent properties light-emitting diodes (PeLEDs). Recently, numerous studies have been conducted on ligands that surround surface crystals passivate sites to improve performance PeLEDs. In this study, a 4-aminobenzonitrile (ABN) ligand improved methylammonium lead bromide (MAPbBr3)-based PeLEDs by reducing MAPbBr3 size nanoscale density. Moreover, with ABN were further using surface-modified...