Hyeuk Jin Han - Academia.edu (original) (raw)
Papers by Hyeuk Jin Han
Advanced Functional Materials, 2022
Topological crystalline insulator tin telluride (SnTe) provides a rich playground to examine inte... more Topological crystalline insulator tin telluride (SnTe) provides a rich playground to examine interactions of correlated electronic states, such as ferroelectricity, topological surface states, and superconductivity. Making SnTe into nanowires further induces novel electronic states due to one-dimensional (1D) confinement effects. Thus, for transport measurements, SnTe nanowires must be made narrow in their diameters to ensure the 1D confinement and phase coherence of the topological surface electrons. This study reports a facile growth method to produce narrow SnTe nanowires with a high yield using alloy nanoparticles as growth catalysts. The average
npj Quantum Materials, 2021
A Josephson junction (JJ) couples the supercurrent flowing between two weakly linked superconduct... more A Josephson junction (JJ) couples the supercurrent flowing between two weakly linked superconductors to the phase difference between them via a current-phase relation (CPR). While a sinusoidal CPR is expected for conventional junctions with insulating weak links, devices made from some exotic materials may give rise to unconventional CPRs and unusual Josephson effects. In this work, we present such a case: we investigate the proximity-induced superconductivity in SnTe nanowires by incorporating them as weak links in JJs and observe a deviation from the standard CPR. We report on indications of an unexpected breaking of time-reversal symmetry in these devices, detailing the unconventional characteristics that reveal this behavior. These include an asymmetric critical current in the DC Josephson effect, a prominent second harmonic in the AC Josephson effect, and a magnetic diffraction pattern with a minimum in critical current at zero magnetic field. The analysis examines how multiban...
Advanced Materials, 2020
Although hexagonal boron nitride (BN) nanostructures have recently received significant attention... more Although hexagonal boron nitride (BN) nanostructures have recently received significant attention due to their unique physical and chemical properties, their applications have been limited by a lack of processability and poor film quality. In this study, a versatile method to transfer‐print high‐quality BN films composed of densely stacked BN nanosheets based on a desolvation‐induced adhesion switching (DIAS) mechanism is developed. It is shown that edge functionalization of BN sheets and rational selection of membrane surface energy combined with systematic control of solvation and desolvation status enable extensive tunability of interfacial interactions at BN–BN, BN–membrane, and BN–substrate boundaries. Therefore, without incorporating any additives in the BN film and applying any surface treatment on target substrates, DIAS achieves a near 100% transfer yield of pure BN films on diverse substrates, including substrates containing significant surface irregularities. The printed BNs demonstrate high optical transparency (>90%) and excellent thermal conductivity (>167 W m−1 K−1) for few‐micrometer‐thick films due to their dense and well‐ordered microstructures. In addition to outstanding heat dissipation capability, substantial optical enhancement effects are confirmed for light‐emitting, photoluminescent, and photovoltaic devices, demonstrating their remarkable promise for next‐generation optoelectronic device platforms.
Advanced Functional Materials, 2021
Science Advances, 2021
Thermodynamically unstable nanoscale grains can be stabilized by tuning the metal-to-oxygen ratio... more Thermodynamically unstable nanoscale grains can be stabilized by tuning the metal-to-oxygen ratio in metal oxide nanoribbons.
Science Advances, 2021
3D customized Pt nanoarchitecture realizes large surface area and porosity for excellent performa... more 3D customized Pt nanoarchitecture realizes large surface area and porosity for excellent performance and durability in fuel cells.
Advanced Materials, 2021
Practical sensing applications such as real-time safety alerts and clinical diagnoses require sen... more Practical sensing applications such as real-time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, yet conventional devices such as oxide-based chemo-resistive sensors and metal-based surface-enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. Here, a label-free, chemo-resistive/SERS multimodal sensor based on a systematically assembled 3D cross-point multifunctional nanoarchitecture (3D-CMA), which has unusually strong enhancements in both "chemo-resistive" and "SERS" sensing characteristics is introduced. 3D-CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO2 nanowire frameworks and dual-functioning Au metallic nanoparticles. It is shown that the multimodal sensor can successfully estimate mixed-gas compositions selectively and quantitatively at the sub-100 ppm level, even for mixtures of gaseous aromatic compounds (nitrobenzene and toluene) with very similar molecular structures. This is enabled by combined chemo-resistive and SERS multimodal sensing providing complementary information.
Journal of Materials Chemistry C, 2021
A block copolymer system containing a gradient-random block enables the vertical orientation of n... more A block copolymer system containing a gradient-random block enables the vertical orientation of nanoscale patterns on any type of surface.
Matter, 2021
Topological nanowires, topological materials confined in one dimension, hold great promise for ro... more Topological nanowires, topological materials confined in one dimension, hold great promise for robust and scalable quantum computing and low-dissipation interconnects, which will transform current computing technologies. To do so, research in topological nanowires must continue to improve their synthesis and properties.
Nature Communications, 2020
Despite highly promising characteristics of three-dimensionally (3D) nanostructured catalysts for... more Despite highly promising characteristics of three-dimensionally (3D) nanostructured catalysts for the oxygen evolution reaction (OER) in polymer electrolyte membrane water electrolyzers (PEMWEs), universal design rules for maximizing their performance have not been explored. Here we show that woodpile (WP)-structured Ir, consisting of 3D-printed, highly-ordered Ir nanowire building blocks, improve OER mass activity markedly. The WP structure secures the electrochemically active surface area (ECSA) through enhanced utilization efficiency of the extended surface area of 3D WP catalysts. Moreover, systematic control of the 3D geometry combined with theoretical calculations and various electrochemical analyses reveals that facile transport of evolved O2 gas bubbles is an important contributor to the improved ECSA-specific activity. The 3D nanostructuring-based improvement of ECSA and ECSA-specific activity enables our well-controlled geometry to afford a 30-fold higher mass activity of ...
Advanced Functional Materials, 2020
Recent advances in surface-enhanced Raman spectroscopy (SERS) have resulted in multiplexing with ... more Recent advances in surface-enhanced Raman spectroscopy (SERS) have resulted in multiplexing with unprecedented levels of sensitivity and selectivity in trace-amount detection. However, quantification of multiple trace-amount molecules with ng-level accuracy has yet to be demonstrated due to nonuniform distribution of SERS enhancement and random adsorption of molecules at low concentrations. While Raman reporter-free SERS is favorable for quantification in that the unique fingerprint spectra of molecules enable specific molecular identification, it has yet to be demonstrated due to poor reproducibility and insufficient SERS enhancement. Raman reporter-free multiplex SERS with highly accurate quantification is successfully realized by versatile aptamer-functionalized plasmonic Au nanogrids with uniform SERS enhancement. By cross-point nano-welding, monolithic Au nanogrids with excellent uniformity and high stability in aqueous media are produced. Raman reporter-free multiplex detection and highly accurate quantification of concentration and composition is realized at picomolar levels. As a demonstration, Au nanogrids functionalized with bisphenol A-specific aptamers successfully detect and quantify trace-amounts of bisphenol A (8.49 ng) from thermal receipt paper. Moreover, principal component analysis is applied to multiplex SERS spectra to establish a ternary composition map, which can potentially serve as a practical reference for future Raman reporterfree SERS.
APL Materials, 2020
Epitaxial strain and the magnetic properties of canted antiferromagnetic perovskite NaNiF 3 thin ... more Epitaxial strain and the magnetic properties of canted antiferromagnetic perovskite NaNiF 3 thin films APL Materials 8, 011101 (2020);
ACS Applied Materials & Interfaces, 2019
ACS Applied Materials & Interfaces, 2019
Herein, we report a siloxane-encapsulated upconversion nanoparticle hybrid composite (SE-UCNP) wh... more Herein, we report a siloxane-encapsulated upconversion nanoparticle hybrid composite (SE-UCNP) which exhibits excellent photoluminescence (PL) stability for over 40 days even at elevated temperature, in high humidity, and in harsh chemicals. The SE-UCNP is synthesized through UV-induced free-radical polymerization of sol-gel derived UCNP-containing oligosiloxane resin (UCNP-Oligosiloxane). The siloxane matrix with random network structure by Si-O-Si bonds successfully encapsulates the UCNPs with chemical linkages between the siloxane matrix and organic ligands on UCNPs. This encapsulation results in surface passivation retaining intrinsic fluorescent properties of UCNPs under severe conditions (e.g., 85 °C, 85% relative humidity) and a wide range of pH (from 1 to 14). As an application example, we fabricate a two-color binary micro-barcode based on SE-UCNP via a low-cost transfer printing process. Under near-infrared irradiation, the binary-sequences in our barcode are readable enough to identify objects using a mobile phone camera. The hybridization of UCNPs with a siloxane matrix provides the capacity for highly stable UCNP-based applications in real environments.
Solar Energy Materials and Solar Cells, 2018
Vanadium dioxide (VO 2) thin films are key materials for thermochromic smart windows and commonly... more Vanadium dioxide (VO 2) thin films are key materials for thermochromic smart windows and commonly have a typical phase transition (insulator to metal phase) at a transition temperature of 68°C. This research, however, found that highly crystallized VO 2 nanoparticles can be successfully coated on a glass substrate with added functionalities, such as higher luminous transmittance and transition efficiency. The transition temperature revealed that the VO 2 nanoparticles with post thermal treatment at 600°C also clearly exhibited a reduced transition temperature of 69°C in the heating curve, 59°C in the cooling curve, and a transition width of 10°C. By nanopatterning the thin films, we were able to prepare VO 2 thin films with higher luminous transmittance than that attained with non-patterned VO 2 thin films. The enhanced transition property was demonstrated using highly crystallized VO 2 nanoparticles induced by post thermal treatment, and the luminous transmittance was improved by the nanopatterns on the surface of the VO 2 thin films.
Advanced Functional Materials, 2022
Topological crystalline insulator tin telluride (SnTe) provides a rich playground to examine inte... more Topological crystalline insulator tin telluride (SnTe) provides a rich playground to examine interactions of correlated electronic states, such as ferroelectricity, topological surface states, and superconductivity. Making SnTe into nanowires further induces novel electronic states due to one-dimensional (1D) confinement effects. Thus, for transport measurements, SnTe nanowires must be made narrow in their diameters to ensure the 1D confinement and phase coherence of the topological surface electrons. This study reports a facile growth method to produce narrow SnTe nanowires with a high yield using alloy nanoparticles as growth catalysts. The average
npj Quantum Materials, 2021
A Josephson junction (JJ) couples the supercurrent flowing between two weakly linked superconduct... more A Josephson junction (JJ) couples the supercurrent flowing between two weakly linked superconductors to the phase difference between them via a current-phase relation (CPR). While a sinusoidal CPR is expected for conventional junctions with insulating weak links, devices made from some exotic materials may give rise to unconventional CPRs and unusual Josephson effects. In this work, we present such a case: we investigate the proximity-induced superconductivity in SnTe nanowires by incorporating them as weak links in JJs and observe a deviation from the standard CPR. We report on indications of an unexpected breaking of time-reversal symmetry in these devices, detailing the unconventional characteristics that reveal this behavior. These include an asymmetric critical current in the DC Josephson effect, a prominent second harmonic in the AC Josephson effect, and a magnetic diffraction pattern with a minimum in critical current at zero magnetic field. The analysis examines how multiban...
Advanced Materials, 2020
Although hexagonal boron nitride (BN) nanostructures have recently received significant attention... more Although hexagonal boron nitride (BN) nanostructures have recently received significant attention due to their unique physical and chemical properties, their applications have been limited by a lack of processability and poor film quality. In this study, a versatile method to transfer‐print high‐quality BN films composed of densely stacked BN nanosheets based on a desolvation‐induced adhesion switching (DIAS) mechanism is developed. It is shown that edge functionalization of BN sheets and rational selection of membrane surface energy combined with systematic control of solvation and desolvation status enable extensive tunability of interfacial interactions at BN–BN, BN–membrane, and BN–substrate boundaries. Therefore, without incorporating any additives in the BN film and applying any surface treatment on target substrates, DIAS achieves a near 100% transfer yield of pure BN films on diverse substrates, including substrates containing significant surface irregularities. The printed BNs demonstrate high optical transparency (>90%) and excellent thermal conductivity (>167 W m−1 K−1) for few‐micrometer‐thick films due to their dense and well‐ordered microstructures. In addition to outstanding heat dissipation capability, substantial optical enhancement effects are confirmed for light‐emitting, photoluminescent, and photovoltaic devices, demonstrating their remarkable promise for next‐generation optoelectronic device platforms.
Advanced Functional Materials, 2021
Science Advances, 2021
Thermodynamically unstable nanoscale grains can be stabilized by tuning the metal-to-oxygen ratio... more Thermodynamically unstable nanoscale grains can be stabilized by tuning the metal-to-oxygen ratio in metal oxide nanoribbons.
Science Advances, 2021
3D customized Pt nanoarchitecture realizes large surface area and porosity for excellent performa... more 3D customized Pt nanoarchitecture realizes large surface area and porosity for excellent performance and durability in fuel cells.
Advanced Materials, 2021
Practical sensing applications such as real-time safety alerts and clinical diagnoses require sen... more Practical sensing applications such as real-time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, yet conventional devices such as oxide-based chemo-resistive sensors and metal-based surface-enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. Here, a label-free, chemo-resistive/SERS multimodal sensor based on a systematically assembled 3D cross-point multifunctional nanoarchitecture (3D-CMA), which has unusually strong enhancements in both "chemo-resistive" and "SERS" sensing characteristics is introduced. 3D-CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO2 nanowire frameworks and dual-functioning Au metallic nanoparticles. It is shown that the multimodal sensor can successfully estimate mixed-gas compositions selectively and quantitatively at the sub-100 ppm level, even for mixtures of gaseous aromatic compounds (nitrobenzene and toluene) with very similar molecular structures. This is enabled by combined chemo-resistive and SERS multimodal sensing providing complementary information.
Journal of Materials Chemistry C, 2021
A block copolymer system containing a gradient-random block enables the vertical orientation of n... more A block copolymer system containing a gradient-random block enables the vertical orientation of nanoscale patterns on any type of surface.
Matter, 2021
Topological nanowires, topological materials confined in one dimension, hold great promise for ro... more Topological nanowires, topological materials confined in one dimension, hold great promise for robust and scalable quantum computing and low-dissipation interconnects, which will transform current computing technologies. To do so, research in topological nanowires must continue to improve their synthesis and properties.
Nature Communications, 2020
Despite highly promising characteristics of three-dimensionally (3D) nanostructured catalysts for... more Despite highly promising characteristics of three-dimensionally (3D) nanostructured catalysts for the oxygen evolution reaction (OER) in polymer electrolyte membrane water electrolyzers (PEMWEs), universal design rules for maximizing their performance have not been explored. Here we show that woodpile (WP)-structured Ir, consisting of 3D-printed, highly-ordered Ir nanowire building blocks, improve OER mass activity markedly. The WP structure secures the electrochemically active surface area (ECSA) through enhanced utilization efficiency of the extended surface area of 3D WP catalysts. Moreover, systematic control of the 3D geometry combined with theoretical calculations and various electrochemical analyses reveals that facile transport of evolved O2 gas bubbles is an important contributor to the improved ECSA-specific activity. The 3D nanostructuring-based improvement of ECSA and ECSA-specific activity enables our well-controlled geometry to afford a 30-fold higher mass activity of ...
Advanced Functional Materials, 2020
Recent advances in surface-enhanced Raman spectroscopy (SERS) have resulted in multiplexing with ... more Recent advances in surface-enhanced Raman spectroscopy (SERS) have resulted in multiplexing with unprecedented levels of sensitivity and selectivity in trace-amount detection. However, quantification of multiple trace-amount molecules with ng-level accuracy has yet to be demonstrated due to nonuniform distribution of SERS enhancement and random adsorption of molecules at low concentrations. While Raman reporter-free SERS is favorable for quantification in that the unique fingerprint spectra of molecules enable specific molecular identification, it has yet to be demonstrated due to poor reproducibility and insufficient SERS enhancement. Raman reporter-free multiplex SERS with highly accurate quantification is successfully realized by versatile aptamer-functionalized plasmonic Au nanogrids with uniform SERS enhancement. By cross-point nano-welding, monolithic Au nanogrids with excellent uniformity and high stability in aqueous media are produced. Raman reporter-free multiplex detection and highly accurate quantification of concentration and composition is realized at picomolar levels. As a demonstration, Au nanogrids functionalized with bisphenol A-specific aptamers successfully detect and quantify trace-amounts of bisphenol A (8.49 ng) from thermal receipt paper. Moreover, principal component analysis is applied to multiplex SERS spectra to establish a ternary composition map, which can potentially serve as a practical reference for future Raman reporterfree SERS.
APL Materials, 2020
Epitaxial strain and the magnetic properties of canted antiferromagnetic perovskite NaNiF 3 thin ... more Epitaxial strain and the magnetic properties of canted antiferromagnetic perovskite NaNiF 3 thin films APL Materials 8, 011101 (2020);
ACS Applied Materials & Interfaces, 2019
ACS Applied Materials & Interfaces, 2019
Herein, we report a siloxane-encapsulated upconversion nanoparticle hybrid composite (SE-UCNP) wh... more Herein, we report a siloxane-encapsulated upconversion nanoparticle hybrid composite (SE-UCNP) which exhibits excellent photoluminescence (PL) stability for over 40 days even at elevated temperature, in high humidity, and in harsh chemicals. The SE-UCNP is synthesized through UV-induced free-radical polymerization of sol-gel derived UCNP-containing oligosiloxane resin (UCNP-Oligosiloxane). The siloxane matrix with random network structure by Si-O-Si bonds successfully encapsulates the UCNPs with chemical linkages between the siloxane matrix and organic ligands on UCNPs. This encapsulation results in surface passivation retaining intrinsic fluorescent properties of UCNPs under severe conditions (e.g., 85 °C, 85% relative humidity) and a wide range of pH (from 1 to 14). As an application example, we fabricate a two-color binary micro-barcode based on SE-UCNP via a low-cost transfer printing process. Under near-infrared irradiation, the binary-sequences in our barcode are readable enough to identify objects using a mobile phone camera. The hybridization of UCNPs with a siloxane matrix provides the capacity for highly stable UCNP-based applications in real environments.
Solar Energy Materials and Solar Cells, 2018
Vanadium dioxide (VO 2) thin films are key materials for thermochromic smart windows and commonly... more Vanadium dioxide (VO 2) thin films are key materials for thermochromic smart windows and commonly have a typical phase transition (insulator to metal phase) at a transition temperature of 68°C. This research, however, found that highly crystallized VO 2 nanoparticles can be successfully coated on a glass substrate with added functionalities, such as higher luminous transmittance and transition efficiency. The transition temperature revealed that the VO 2 nanoparticles with post thermal treatment at 600°C also clearly exhibited a reduced transition temperature of 69°C in the heating curve, 59°C in the cooling curve, and a transition width of 10°C. By nanopatterning the thin films, we were able to prepare VO 2 thin films with higher luminous transmittance than that attained with non-patterned VO 2 thin films. The enhanced transition property was demonstrated using highly crystallized VO 2 nanoparticles induced by post thermal treatment, and the luminous transmittance was improved by the nanopatterns on the surface of the VO 2 thin films.