A5030004296- Advanced Thermoelectric Materials and Devices
- Thermal properties of materials
- Chalcogenide Semiconductor Thin Films
- Thermal Radiation and Cooling Technologies
- ZnO doping and properties
- Advanced Thermodynamics and Statistical Mechanics
- Heusler alloys: electronic and magnetic properties
- Advanced Photocatalysis Techniques
- 2D Materials and Applications
- TiO2 Photocatalysis and Solar Cells
- Gas Sensing Nanomaterials and Sensors
- Advancements in Battery Materials
- Quantum Dots Synthesis And Properties
- Advanced Sensor and Energy Harvesting Materials
- Semiconductor materials and devices
- Ga2O3 and related materials
- Supercapacitor Materials and Fabrication
- Engineering Applied Research
- Ferroelectric and Piezoelectric Materials
- Advanced Battery Materials and Technologies
- Copper-based nanomaterials and applications
- Multiferroics and related materials
- Surface Modification and Superhydrophobicity
- MXene and MAX Phase Materials
- GaN-based semiconductor devices and materials
University of Seoul
2019-2025
Sogang University
2025
California Institute of Technology
2012-2024
Hongik University
2018-2024
SK Group (South Korea)
2022-2024
Korea Institute of Ceramic Engineering and Technology
2015-2024
University of Cincinnati
2021-2024
Korea Advanced Institute of Science and Technology
2024
Northwestern University
2015-2024
Seoul National University
2003-2022
The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency the bulk alloys, which evaluated in terms dimensionless figure merit (zT). zT alloys can be improved reducing lattice thermal conductivity through grain boundary and point-defect scattering, target low- high-frequency phonons. Dense dislocation arrays formed at low-energy boundaries liquid-phase compaction Bi(0.5)Sb(1.5)Te3 (bismuth antimony telluride) effectively scatter midfrequency...
In analyzing zT improvements due to lattice thermal conductivity (κL) reduction, electrical (σ) and total (κTotal) are often used estimate the electronic component of (κE) in turn κL from = ∼ κTotal − LσT. The Wiedemann-Franz law, κE LσT, where L is Lorenz number, widely σ measurements. It a common practice treat as universal factor with 2.44 × 10−8 WΩK−2 (degenerate limit). However, significant deviations degenerate limit (approximately 40% or more for Kane bands) known occur non-degenerate...
A p-type ZnO was prepared on a sapphire substrate using P2O5 as phosphorus dopant. As-grown n-type films doped with showed electron concentrations of 1016–1017/cm3 and these were converted to by thermal annealing process at temperature above 800 °C under N2 ambient. The electrical properties the hole concentration 1.0×1017–1.7×1019/cm3, mobility 0.53–3.51 cm2/V s, low resistivity 0.59–4.4 Ω cm. phosphorus-doped thin strong photoluminescence peak 3.35 eV 10 K, which is closely related neutral...
Recent reports on epitaxial BiFeO${}_{3}$ films show that the crystal structure changes from nearly rhombohedral (``$R$ like'') to tetragonal (``$T$ at strains exceeding \ensuremath{\approx}\ensuremath{-}4.5%, with $T$-like being characterized by a highly enhanced $c$/$a$ ratio. While both $R$-like and phases are monoclinic, our detailed x-ray diffraction results reveal symmetry change ${M}_{A}$ ${M}_{C}$ type, respectively, this $R$-like-to-$T$-like transition. Therefore, ferroelectric...
In characterizing thermoelectric materials, electrical and thermal transport measurements are often used to estimate electronic band structure properties such as the effective mass gap. The Goldsmid-Sharp gap, Eg = 2e|S|maxTmax, is a tool widely employed gap from temperature dependent Seebeck coefficient measurements. However, significant deviations of more than factor two now known occur. We find that this when either majority-to-minority weighted mobility ratio (A) becomes very different...
Bi2Te3 has been recognized as an important cooling material for thermoelectric applications. Yet its performance could still be improved. Here we propose a band engineering strategy by optimizing the converging valence bands of and Sb2Te3 in (Bi1−xSbx)2Te3 system when x = 0.75. Band convergence successfully explains sharp increase density-of-states effective mass yet relatively constant mobility optical gap measurement. This picture guides carrier concentration tuning optimum performance. To...
Recently, flexible capacitive pressure sensors have received significant attention in the field of wearable electronics. The high sensitivity over a wide linear range combined with long-term durability is critical requirement for fabrication reliable versatile applications. Herein, we propose special approach to enhance and linearity sensor by fabricating hybrid ionic nanofibrous membrane as sensing layer composed Ti3C2Tx MXene an salt lithium sulfonamides poly(vinyl alcohol) elastomer...
Abstract Smart electronic skin (e‐skin) requires the easy incorporation of multifunctional sensors capable mimicking skin‐like perception in response to external stimuli. However, efficient and reliable measurement multiple parameters a single functional device is limited by sensor layout choice materials. The outstanding electrical properties black phosphorus laser‐engraved graphene (BP@LEG) demonstrates new paradigm for highly sensitive dual‐modal temperature strain platform modulate...
Abstract Band engineering is an effective strategy to improve the electronic transport properties of semiconductors. In thermoelectric materials research, density‐of‐states mass undoubted key factor in verifying band effect and establishing a for enhancing performance. However, estimation demanding or inaccurate depending on methods taken. A simple equation proposed, valid all degeneracy: Log 10 ( m d * T /300) = (2/3) n ) − [20.3 (0.00508 × | S |) + (1.58 0.967 )] that utilizes...
Phosphorus-doped p-type ZnO thin films were grown on sapphire by radio-frequency magnetron sputtering. The photoluminescence (PL) spectra revealed an acceptor bound exciton peak at 3.355 eV and a conduction band to the transition caused phosphorus related level 3.310 eV. A study of dependence excitation laser power density temperature characteristics PL suggests that emission lines 3.241 can be attributed phosphorus-related donor pair transition, respectively. energy dopant was estimated...
Straight-stranded anatase TiO2 nanotubes were produced by anodic oxidation on a pure titanium substrate in an aqueous solution containing 0.45 wt % NaF electrolyte (pH 4.3 fixed). The average length of the was approximately 3 μm, which had effect level dye adsorption dye-sensitized solar cells. applied as working electrode solid-state cell. An 1 nm ZnO shell coated nanotube to improve open-circuit voltage (Voc) and conversion efficiency cell, retard any back reaction. Although Voc...
A simple and scalable process was developed for the synthesis of highly crystalline magnetite nanocrystals embedded in a carbon matrix using low cost starting materials; resulting nanocomposite showed very high specific capacity 863 mA hg−1 initial cycle retention 90% after 30 cycles.
We report our dynamic analysis of coalescence-induced jumping on superhydrophobic surfaces with a full 3D numerical model supported experiments. The shows that approximately half (40%–60%) the released surface energy during coalescence is converted to kinetic before detachment starts. rapid increase in at beginning initiated from low pressure associated high negative curvature liquid bridge. asymmetric nature droplet evolution wall generates bottom, which provides driving force make merged...
Thermal conductivities of polycrystalline thermoelectric materials are satisfactorily calculated by replacing the commonly used Casimir model (freqeuncy-independent) with grain boundary dislocation strain (frequency-dependent) Klemens. It is demonstrated that boundaries better described as a collection dislocations rather than perfectly scattering interfaces.
Printing techniques could offer a scalable approach to fabricate thermoelectric (TE) devices on flexible substrates for power generation used in wearable and personalized thermo-regulation. However, typical printing processes need large concentration of binder additives, which often render detrimental effect electrical transport the printed TE layers. Here, we report screen-printing layers fiber glass fabrics, by rationally optimizing inks consisting particles (p-type Bi0.5Sb1.5Te3 or n-type...
We explore both the synthesis of Cd-free blue quantum dots (QDs) with high-quality photoluminescence (PL) characteristics and fabrication high-efficiency QD light-emitting diodes (QLEDs). True (445 nm)-emissive, multishelled ZnSeTe QDs a high PL yield 84% sharp bandwidth 27 nm are prepared. To obtain better electron transport layer (ETL) material, surface ZnMgO nanoparticles (NPs) is modified by additional Mg reaction, leading to possible formation Mg(OH)2 on surface-modified (m-ZnMgO) NPs....
We experimentally investigated the impact dynamics of a water drop on oil-infused nanostructured surfaces using high-speed microscopy and scalable metal oxide nano surfaces. The effects physical properties oil velocity complex fluid during were investigated. show that viscosity does not have significant maximal spreading radius drop, while it moderately affects retraction dynamics. also determines stability infused lubricant impact; i.e., low layer is easily displaced by impacting which...