68 results on '"Po-Chun Hsu"'
Search Results
2. Design and Utilization of Infrared Light for Interfacial Solar Water Purification
- Author
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Thomas Cooper, Po-Chun Hsu, Xiuqiang Li, and Wanrong Xie
- Subjects
Fuel Technology ,Materials science ,Renewable Energy, Sustainability and the Environment ,Chemistry (miscellaneous) ,Infrared ,business.industry ,Materials Chemistry ,Energy Engineering and Power Technology ,Optoelectronics ,business ,Solar water - Published
- 2021
3. A Triple-Mode Midinfrared Modulator for Radiative Heat Management of Objects with Various Emissivity
- Author
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Willie J. Padilla, Bowen Sun, Yi-Ting Lai, Po-Chun Hsu, Xiuqiang Li, Haoming Fang, Wanrong Xie, Kebin Fan, and Shu-Lin Bai
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Coupling ,Materials science ,business.industry ,Mechanical Engineering ,Bioengineering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Transmission (telecommunications) ,Thermal radiation ,Heat transfer ,Transmittance ,Reflection (physics) ,Emissivity ,Optoelectronics ,General Materials Science ,Thermal emittance ,0210 nano-technology ,business - Abstract
Thermal management is ubiquitous in the modern world and indispensable for a sustainable future. Radiative heat management provides unique advantages because the heat transfer can be controlled by the surface. However, different object emissivities require different tuning strategies, which poses challenges to develop dynamic and universal radiative heat management devices. Here, we demonstrate a triple-mode midinfrared modulator that can switch between passive heating and cooling suitable for all types of object surface emissivities. The device comprises a surface-textured infrared-semiabsorbing elastomer coated with a metallic back reflector, which is biaxially strained to sequentially achieve three fundamental modes: emission, reflection, and transmission. By analyzing and optimizing the coupling between optical and mechanical properties, we achieve a performance as follows: emittance contrast Δε = 0.58, transmittance contrast Δτ = 0.49, and reflectance contrast Δρ = 0.39. The device can provide a new design paradigm of radiation heat regulation for wearable, robotics, and camouflage technologies.
- Published
- 2021
4. Investigation of Defect Characteristics and Carrier Transport Mechanisms in GaN Layers With Different Carbon Doping Concentration
- Author
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Ming Zhao, Hongyue Wang, Jinyan Wang, A. Sibaja-Hernandez, Eddy Simoen, and Po-Chun Hsu
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Technology ,Materials science ,Silicon ,N-TYPE GAN ,DEEP LEVELS ,chemistry.chemical_element ,Gallium nitride ,Electron ,01 natural sciences ,Physics, Applied ,chemistry.chemical_compound ,Engineering ,GaN buffer ,0103 physical sciences ,transport mechanism ,Rectangular potential barrier ,SI ,Electrical and Electronic Engineering ,defects ,010302 applied physics ,Science & Technology ,Condensed matter physics ,Physics ,Doping ,Engineering, Electrical & Electronic ,TRAPS ,Biasing ,Electronic, Optical and Magnetic Materials ,Carbon doping ,STATES ,chemistry ,Physical Sciences ,LUMINESCENCE ,Luminescence ,Carbon - Abstract
In this article, a metal/carbon-doped GaN (GaN:C)/Si-doped GaN (GaN:Si) structure was used to investigate the defect characteristics and carrier transport mechanisms in GaN:C layers with different carbon doping concentration. Capacitance-voltage, current–voltage, and deep-level transient spectroscopy measurements were performed at different temperatures. At forward bias, a pinning effect was found at the interface of the GaN:C/GaN:Si layer, due to the defects capturing electrons. The forward currents of the samples with high carbon doping concentration ( ${N}_{C}> {1} \times 10^{{19}}$ cm−3) increase gradually with increasing forward bias voltage. Ohm’s law, space-charge-limited current, and variable-range-hopping mechanisms may dominate the forward current. For the samples with low carbon doping concentration ( ${N}_{C} cm−3), a device turning on behavior was observed, which is attributed to the carriers overcoming a potential barrier. In addition, the DLTS spectra reveal that only electron trapping happens at forward bias for the samples with high carbon doping concentration, while, in addition, hole trapping was observed for the samples with low carbon doping concentration. The process of the carrier capture by defects was demonstrated.
- Published
- 2020
5. Lithium Extraction from Seawater through Pulsed Electrochemical Intercalation
- Author
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Yanbin Li, Dingchang Lin, Steven Chu, Bofei Liu, Yi Cui, Chong Liu, Po-Chun Hsu, Tong Wu, and Gangbin Yan
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Materials science ,Inorganic chemistry ,Extraction (chemistry) ,Intercalation (chemistry) ,chemistry.chemical_element ,02 engineering and technology ,Crystal structure ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,General Energy ,chemistry ,Electrode ,Seawater ,Lithium ,0210 nano-technology ,Selectivity - Abstract
Summary It is highly attractive to develop efficient methods to directly extract Li from seawater to secure the supply of Li. However, high concentration of Na in the seawater poses a great challenge in Li extraction. Here, we developed pulsed-rest and pulse-rest-reverse pulse-rest electrochemical intercalation methods with TiO2-coated FePO4 electrodes for Li extraction. The method can lower the intercalation overpotential and successfully boost the Li selectivity. Moreover, the pulse-rest-reverse pulse-rest method can also promote electrode crystal structure stability during the co-intercalation of Li and Na and prolong the lifetime of the electrode. We demonstrated 10 cycles of successful and stable Li extraction with 1:1 of Li to Na recovery from authentic seawater, which is equivalent to the selectivity of ∼1.8 × 104. Also, with lake water of higher initial Li/Na ratio of 1.6 × 10−3, we achieved Li extraction with more than 50:1 of Li to Na recovery.
- Published
- 2020
6. Metalized polyamide heterostructure as a moisture-responsive actuator for multimodal adaptive personal heat management
- Author
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Xiuqiang Li, Boran Ma, Jingyuan Dai, Chenxi Sui, Divya Pande, David R. Smith, L. Catherine Brinson, and Po-Chun Hsu
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Multidisciplinary ,Engineering ,Materials Science ,SciAdv r-articles ,Physical and Materials Sciences ,Research Article - Abstract
Description, A wearable device that responds to sweat vapor can switch between radiative heating and evaporative cooling., Personal thermal management textile/wearable is an effective strategy to expand the indoor temperature setpoint range to reduce a building’s energy consumption. Usually, textiles/wearables that were engineered for controlling conduction, convection, radiation, or sweat evaporation have been developed separately. Here, we demonstrate a multimodal adaptive wearable with moisture-responsive flaps composed of a nylon/metal heterostructure, which can simultaneously regulate convection, sweat evaporation, and mid-infrared emission to accomplish large and rapid heat transfer tuning in response to human perspiration vapor. We show that the metal layer not only plays a crucial role in low-emissivity radiative heating but also enhances the bimorph actuation performance. The multimodal adaptive mechanism expands the thermal comfort zone by 30.7 and 20.7% more than traditional static textiles and single-modal adaptive wearables without any electricity and energy input, making it a promising design paradigm for personal heat management.
- Published
- 2021
7. Au-induced improvements in the grain stability and mechanical properties of Ag-based alloy wires under electrical current stressing
- Author
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Fuh-Sheng Shieu, Po-Chun Hsu, Yen-Lin Huang, Bing-Hau Kuo, Hsing-Hua Tsai, Du-Cheng Tsai, T. H. Chuang, and Jun-Der Lee
- Subjects
010302 applied physics ,Materials science ,Annealing (metallurgy) ,Scanning electron microscope ,Alloy ,Electronic packaging ,engineering.material ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Atomic diffusion ,0103 physical sciences ,engineering ,Grain boundary ,Electrical and Electronic Engineering ,Composite material ,Electron backscatter diffraction - Abstract
The evolutions of the surface morphologies, cross-sectional microstructures, and mechanical properties of two types of Ag-based alloy wires with different Au contents under a 105 A/cm2 electrical current density across various times were compared in this study. Ag-based alloy wires that contain 8 wt% Au and 15 wt% Au with 3 wt% Pd were produced via rapid drawing and multiple annealing processes to replace commercial Au-bonded wires in the electronic packaging industry. The surface morphologies of these wires were revealed by scanning electron microscopy (SEM), and cross-sectional microstructures were analyzed by electron back scattering diffraction (EBSD). The SEM observations showed grain- and step-like structures in the Ag–8Au–3Pd and Ag–15Au–3Pd wires after a 5-h treatment, respectively. EBSD results revealed a change in the main preferred orientation from slender grains to equiaxed grains because the high-angle grain boundaries (HAGB) were reduced, and the twin boundaries (TB) were multiplied along the drawing direction. In terms of mechanical properties, Ag–15Au–3Pd wire showed better breaking loads and elongations than Ag–8Au–3Pd wire. The Au effect in Ag-based alloy wires reduced the atomic diffusion to stabilize grain structures and induce a dislocation accumulation, which subsequently improved the mechanical properties by retaining and forming HAGBs, LAGBs, and TBs under high current stressing.
- Published
- 2019
8. (Invited) Electrical Activity of Extended Defects in III-V Semiconductors
- Author
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Cor Claeys, Robert Langer, Nadine Collaert, Eddy Simoen, C Merckling, Marc Heyns, Geert Eneman, Yves Mols, Bernardette Kunert, A. Alian, Po-Chun Hsu, and Niamh Waldron
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Semiconductor ,Materials science ,business.industry ,Optoelectronics ,business - Published
- 2019
9. Effect of alloying Au on the microstructural, mechanical and electrical properties of Ag-based alloy wires
- Author
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Tung-Han Chuang, Po-Chun Hsu, Du-Cheng Tsai, Fuh-Sheng Shieu, Hsing-Hua Tsai, Yen-Lin Huang, Bing-Hau Kuo, and Jun-Der Lee
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010302 applied physics ,Equiaxed crystals ,Materials science ,Annealing (metallurgy) ,Alloy ,engineering.material ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Focused ion beam ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Transmission electron microscopy ,0103 physical sciences ,engineering ,Grain boundary ,Electrical and Electronic Engineering ,Composite material ,Electron backscatter diffraction - Abstract
In this study, the microstructure and performance of different Ag-based conductive wires were investigated. Ag-based wires that contain 8, 15, 20, and 28 wt% Au were produced by multiple drawing and rapid annealing processes to substitute commercial gold wires in electronic packaging industries. The cross-sectional gain structures observed using focused ion beam showed the formation of a slender granular structure at the center, and the outer portion changed from equiaxed to elongated grains with the increase in Au content. High-resolution transmission electron microscopy showed a remarkable decrease in the twin thickness and stacking defect of 9R structures dissociated from incoherent twin boundaries. Electron backscatter diffraction analysis revealed that slender grains at the center showed strong crystallographic orientation, and the equiaxed grains near the surface were in the preferred orientation. The high Au solute concentration in Ag-based wires induced strong interaction on dislocations, thereby resulting in the formation of low-angle grain boundaries (LAGBs) and nano-twins. Ternary Ag-based alloy wires exhibited high strength and hardness but low conductivity and elongation with the increase in Au content because relatively the high LAGB density and Au solute atoms caused strengthening and electron scattering.
- Published
- 2019
10. Bio-Impedance Measurement Optimization for High-Resolution Carotid Pulse Sensing
- Author
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Yuan-Ta Shih, Yen Ling Sung, Ting Wei Wang, Po Chun Hsu, Hao Min Cheng, Lin Chou, Hsiao Wei Chu, and Shien Fong Lin
- Subjects
bio-impedance measurement ,Materials science ,0206 medical engineering ,Hemodynamics ,carotid pulse sensing ,Blood Pressure ,02 engineering and technology ,Pulse Wave Analysis ,lcsh:Chemical technology ,hemodynamics ,Biochemistry ,Article ,Analytical Chemistry ,Quality (physics) ,0202 electrical engineering, electronic engineering, information engineering ,Electric Impedance ,Plethysmograph ,Humans ,lcsh:TP1-1185 ,Plethysmography, Impedance ,Electrical and Electronic Engineering ,Pulse ,Instrumentation ,Electrical impedance ,Pulse (signal processing) ,020208 electrical & electronic engineering ,Blood Pressure Determination ,020601 biomedical engineering ,Atomic and Molecular Physics, and Optics ,Carotid pulse ,Blood pressure ,Electrode ,cardiovascular monitoring ,impedance plethysmography (IPG) ,Biomedical engineering ,continuous blood pressure - Abstract
Continuous hemodynamic monitoring is important for long-term cardiovascular healthcare, especially in hypertension. The impedance plethysmography (IPG) based carotid pulse sensing is a non-invasive diagnosis technique for measuring pulse signals and further evaluating the arterial conditions of the patient such as continuous blood pressure (BP) monitoring. To reach the high-resolution IPG-based carotid pulse detection for cardiovascular applications, this study provides an optimized measurement parameter in response to obvious pulsation from the carotid artery. The influence of the frequency of excitation current, electrode cross-sectional area, electrode arrangements, and physiological site of carotid arteries on IPG measurement resolution was thoroughly investigated for optimized parameters. In this study, the IPG system was implemented and installed on the subject’s neck above the carotid artery to evaluate the measurement parameters. The measurement results within 6 subjects obtained the arterial impedance variation of 2137 mΩ using the optimized measurement conditions, including excitation frequency of 50 kHz, a smaller area of 2 cm2, electrode spacing of 4 cm and 1.7 cm for excitation and sensing functions, and location on the left side of the neck. The significance of this study demonstrates an optimized measurement methodology of IPG-based carotid pulse sensing that greatly improves the measurement quality in cardiovascular monitoring.
- Published
- 2021
11. A Triple-Mode Mid-infrared Modulator for All-Surface Radiative Thermal Management
- Author
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Willie J. Padilla, Yi-Ting Lai, Wanrong Xie, Kebin Fan, Bowen Sun, Po-Chun Hsu, Xiuqiang Li, Haoming Fang, and Shu-Lin Bai
- Subjects
Surface (mathematics) ,Condensed Matter - Materials Science ,Materials science ,business.industry ,Mode (statistics) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Physics - Applied Physics ,Applied Physics (physics.app-ph) ,Condensed Matter - Soft Condensed Matter ,Modulation ,Attenuation coefficient ,Radiative transfer ,Transmittance ,Emissivity ,Soft Condensed Matter (cond-mat.soft) ,Optoelectronics ,Thermal emittance ,business ,Astrophysics::Galaxy Astrophysics ,Physics - Optics ,Optics (physics.optics) - Abstract
Thermal management is ubiquitous in the modern world and indispensable for a sustainable future. Radiative heat management provides unique advantages because the heat transfer can be controlled by the surface. However, different surface emissivities require different tuning strategies. Here, we demonstrate a triple-mode mid-infrared modulator that can switch between passive heating and cooling suitable for all types of object surface emissivities. The device is composed of a surface-textured infrared-semi-transparent elastomer coated with a metallic back reflector, which is biaxially strained to sequentially achieve three fundamental modes: emission, reflection, and transmission. By analyzing and optimizing the coupling between optical and mechanical properties, we achieve a performance of emittance contrast = 0.58, transmittance contrast = 0.49, and reflectance contrast = 0.39. The device can provide a new design paradigm of radiation heat regulation to develop the next generation wearable devices, robotics, and camouflage technology.
- Published
- 2021
12. Analysis of semi-insulating carbon-doped GaN layers using deep-level transient spectroscopy
- Author
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Stefan De Gendt, Po-Chun Hsu, Jinyan Wang, Ming Zhao, Hongyue Wang, Eddy Simoen, and A. Sibaja-Hernandez
- Subjects
Materials science ,Deep-level transient spectroscopy ,business.industry ,General Physics and Astronomy ,Insulator (electricity) ,TRAPS ,Electron ,Penning trap ,Chemistry ,Semiconductor ,Physics and Astronomy ,Vacancy defect ,Optoelectronics ,Charge carrier ,business ,DEFECT STATES ,Voltage - Abstract
Electrically active defects in carbon-doped GaN layers were studied with a metal/carbon-doped GaN (GaN:C)/Si-doped GaN (GaN:Si) MIS structure. The GaN:C layers were grown with three different carbon doping concentrations (N-C). A semi-vertical metal/semi-insulator/n-type semiconductor (MIS) device was fabricated to perform deep-level transient spectroscopy (DLTS) measurements. Two electron traps E1 and E2 with energy level at E-C - (0.22-0.31) eV and E-C - (0.45-0.49) eV were observed. E1 and E2 are associated with a nitrogen vacancy V-N-related defect in the strain field of extended defects and a nitrogen antisite defect, respectively. By changing the reverse bias voltage of the DLTS measurement, the location and relative defect concentration of the E1 and E2 traps could be verified. A dominant electron trap E3 with an unusual capture cross section was only observed in devices with an N-C = 2 x 10(19 )cm(-3) GaN:C layer. This may charge carriers from a defect band and lead to the charge redistribution in the GaN:C layer when forward biased. A hole trap H1 with energy level at E-V + 0.47 eV was found for the pulse bias in the forward ON-state. H1 is suggested to correspond with the C-N induced 0/+ donor level. By analyzing the schematic band diagrams across the MIS structure, the carrier transport and defect charging mechanisms underlying the DLTS transient measurements are illustrated. The identification of the trap states in the carbon-doped GaN with different N-C gives further understanding on the carbon doping impact on electric characteristics of GaN power devices made on Si substrates.
- Published
- 2021
13. Effect of Au Addition on the Microstructure and Properties of Ag-4Pd Bonding Wires
- Author
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Du-Cheng Tsai, Fuh-Sheng Shieu, Yen-Lin Huang, Bing-Hau Kuo, Tung-Han Chuang, Po-Chun Hsu, and Hsing-Hua Tsai
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010302 applied physics ,Materials science ,Structural material ,Metallurgy ,Metals and Alloys ,Intermetallic ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Mechanics of Materials ,Transmission electron microscopy ,Phase (matter) ,0103 physical sciences ,Scanning transmission electron microscopy ,Composite material ,0210 nano-technology ,Layer (electronics) ,Electrical conductor - Abstract
Silver-based bonding wires such as Ag-4Pd and Ag-8Au-3Pd have drawn remarkable attention in the packaging industry because they are cheaper and more conductive than Au- and Cu-based wires, respectively. This study aimed to investigate the intermetallic compound (IMC) formation and growth at the bonding interface between Ag-4Pd wire and Al-pads and between Ag-8Au-3Pd wire and Al-pads. The as-bonded and reliability-tested Ag-4Pd/Al and Ag-8Au-3Pd/Al specimens were then investigated by transmission electron microscopy (TEM) and scanning transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy (STEM-EDS). The bonding properties were examined by ball shear and wire pull tests. In the as-bonded state, hexagonal close-packed (HCP) (Ag, Pd)2Al and HCP Ag2Al were formed at the Ag-4Pd/Al interfaces, whereas dual phase consisting of face-centered cubic Ag alloy with HCP precipitates (Ag, Au, Pd)2Al crystals and HCP Ag2Al layers were observed at the Ag-8Au-3Pd/Al interfaces. The IMCs showed significant growth and oxidation during reliability tests at 130 °C and 85 pct relative humidity for 192 hours. Alloying Au in Ag-4Pd wires promoted the growth of the IMC layer and it also enhanced the mechanical properties in the as-bonded material. By contrast, overgrowth of the IMCs in the Ag-8Au-3Pd/Al system induced microcrack formation in bonding and thus degraded the reliability of the material.
- Published
- 2018
14. Core–Shell Nanofibrous Materials with High Particulate Matter Removal Efficiencies and Thermally Triggered Flame Retardant Properties
- Author
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Tong Wu, Kai Liu, Guangmin Zhou, Po-Chun Hsu, Biao Kong, Yi Cui, Chong Liu, Rufan Zhang, William Huang, Jie Sun, and Jinwei Xu
- Subjects
Pressure drop ,Materials science ,Atmospheric pressure ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,Particulates ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial waste ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Chemistry ,Chemical engineering ,chemistry ,law ,0210 nano-technology ,Dust explosion ,QD1-999 ,Filtration ,Fire retardant ,Triphenyl phosphate ,Research Article - Abstract
Dust filtration is a crucial process for industrial waste gas treatment. Great efforts have been devoted to improve the performance of dust filtration filters both in industrial and fundamental research. Conventional air-filtering materials are limited by three key issues: (1) Low filtration efficiency, especially for particulate matter (PM) below 1 μm; (2) large air pressure drops across the filter, which require a high energy input to overcome; and (3) safety hazards such as dust explosions and fires. Here, we have developed a “smart” multifunctional material which can capture PM with high efficiency and an extremely low pressure drop, while possessing a flame retardant design. This multifunctionality is achieved through a core–shell nanofiber design with the polar polymer Nylon-6 as the shell and the flame retardant triphenyl phosphate (TPP) as the core. At 80% optical transmittance, the multifunctional materials showed capture efficiency of 99.00% for PM2.5 and >99.50% for PM10–2.5, with a pressure drop of only 0.25 kPa (0.2% of atmospheric pressure) at a flow rate of 0.5 m s–1. Moreover, during direct ignition tests, the multifunctional materials showed extraordinary flame retardation; the self-extinguishing time of the filtrate-contaminated filter is nearly instantaneous (0 s/g) compared to 150 s/g for unmodified Nylon-6., A “smart” air filter which can efficiently capture tiny particulate matters while possessing a flame retardant property is developed.
- Published
- 2018
15. Morphology and property investigation of primary particulate matter particles from different sources
- Author
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Yi Cui, Chong Liu, Jie Zhao, Po-Chun Hsu, Jie Sun, Tong Wu, Wenting Zhao, Nian Liu, Haotian Wang, Guangmin Zhou, Rufan Zhang, and Yongcai Qiu
- Subjects
Pollution ,Materials science ,Primary (chemistry) ,010504 meteorology & atmospheric sciences ,media_common.quotation_subject ,Nanoparticle ,02 engineering and technology ,Particulates ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electron spectroscopy ,Atomic and Molecular Physics, and Optics ,Characterization (materials science) ,Environmental chemistry ,Particle ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,0105 earth and related environmental sciences ,media_common - Abstract
Particulate matter (PM) pollution has become a major environmental concern in many developing countries. PM pollution control remains a great challenge owing to the complex sources and evolution processes of PM particles. There are two categories of PM, i.e., primary and secondary PM particles, and the primary PM emissions play a key role in the formation of PM pollution. Knowledge of primary PM particle compositions, sources, and evolution processes is of great importance to the effective control of PM pollution. In order to characterize PM particles effectively, their fundamental properties including the morphology, concentration distribution, surface chemistry, and composition must be systematically investigated. In this study, we collected and analyzed six types of PM10 and PM2.5 particles from different sources using an in situ sampling approach. The concentration distributions of PM particles were analyzed and comparative analysis of the morphologies, distributions, capture mechanisms, and compositions of PM particles was conducted using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. We found that there were significant differences in the structures, morphologies, and capture mechanisms of PM2.5 and PM10 particles. The systematic comparative investigation in this work will benefit the study of evolution processes and the effective control of PM pollution in the future.
- Published
- 2018
16. Nanoporous polyethylene microfibres for large-scale radiative cooling fabric
- Author
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Lili Cai, Yangying Zhu, Yi Cui, Po-Chun Hsu, Peter B. Catrysse, Hye Ryoung Lee, Alex Y. Song, Bofei Liu, Yucan Peng, Shanhui Fan, Jun Chen, Guangmin Zhou, and David Wu
- Subjects
Materials science ,Radiative cooling ,Geography, Planning and Development ,02 engineering and technology ,Management, Monitoring, Policy and Law ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Process engineering ,Nature and Landscape Conservation ,Global and Planetary Change ,Ecology ,Renewable Energy, Sustainability and the Environment ,Nanoporous ,business.industry ,Energy consumption ,Polyethylene ,021001 nanoscience & nanotechnology ,Durability ,0104 chemical sciences ,Renewable energy ,Urban Studies ,Energy conservation ,chemistry ,Extrusion ,0210 nano-technology ,business ,Food Science - Abstract
Global warming and energy crises severely limit the ability of human civilization to develop along a sustainable path. Increasing renewable energy sources and decreasing energy consumption are fundamental steps to achieve sustainability. Technological innovations that allow energy-saving behaviour can support sustainable development pathways. Energy-saving fabrics with a superior cooling effect and satisfactory wearability properties provide a novel way of saving the energy used by indoor cooling systems. Here, we report the large-scale extrusion of uniform and continuous nanoporous polyethylene (nanoPE) microfibres with cotton-like softness for industrial fabric production. The nanopores embedded in the fibre effectively scatter visible light to make it opaque without compromising the mid-infrared transparency. Moreover, using industrial machines, the nanoPE microfibres are utilized to mass produce fabrics. Compared with commercial cotton fabric of the same thickness, the nanoPE fabric exhibits a great cooling power, lowering the human skin temperature by 2.3 °C, which corresponds to a greater than 20% saving on indoor cooling energy. Besides the superior cooling effect, the nanoPE fabric also displays impressive wearability and durability. As a result, nanoPE microfibres represent basic building blocks to revolutionize fabrics for human body cooling and pave an innovative way to sustainable energy. Energy-saving innovations, such as fabrics with cooling effects, contribute to sustainability. This study reports the large-scale extrusion of uniform and continuous nanoporous polyethylene microfibres with cotton-like softness for wearable fabrics. The fabric can lower human skin temperature by 2.3 °C with over 20% savings on indoor cooling energy.
- Published
- 2018
17. In Situ Investigation on the Nanoscale Capture and Evolution of Aerosols on Nanofibers
- Author
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Guangmin Zhou, Bofei Liu, Allen Pei, Chong Liu, Yi Cui, Dingchang Lin, Tong Wu, Rufan Zhang, Po-Chun Hsu, Yayuan Liu, Xuanyi Huang, Wei Chen, Jie Sun, Yang Jin, Jinwei Xu, Ankun Yang, Wenting Zhao, Yangying Zhu, and Jin Xie
- Subjects
In situ ,Materials science ,Mechanical Engineering ,Bioengineering ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Aerosol ,law.invention ,Contact angle ,law ,Nanofiber ,General Materials Science ,Wetting ,0210 nano-technology ,Nanoscopic scale ,Polyimide ,Filtration - Abstract
Aerosol-induced haze problem has become a serious environmental concern. Filtration is widely applied to remove aerosols from gas streams. Despite classical filtration theories, the nanoscale capture and evolution of aerosols is not yet clearly understood. Here we report an in situ investigation on the nanoscale capture and evolution of aerosols on polyimide nanofibers. We discovered different capture and evolution behaviors among three types of aerosols: wetting liquid droplets, nonwetting liquid droplets, and solid particles. The wetting droplets had small contact angles and could move, coalesce, and form axisymmetric conformations on polyimide nanofibers. In contrast, the nonwetting droplets had a large contact angle on polyimide nanofibers and formed nonaxisymmetric conformations. Different from the liquid droplets, the solid particles could not move along the nanofibers and formed dendritic structures. This study provides an important insight for obtaining a deep understanding of the nanoscale capture and evolution of aerosols and benefits future design and development of advanced filters.
- Published
- 2018
18. Defect Characterization in High‐Electron‐Mobility Transistors with Regrown p‐GaN Gate by Low‐Frequency Noise and Deep‐Level Transient Spectroscopy
- Author
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Po-Chun Hsu, Benoit Bakeroot, Hu Liang, Eddy Simoen, Stefaan Decoutere, Dirk Wellekens, and Brice De Jaeger
- Subjects
Materials science ,Deep-level transient spectroscopy ,business.industry ,Infrasound ,Transistor ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Characterization (materials science) ,law ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,business ,High electron - Published
- 2021
19. Photon-engineered radiative cooling textiles
- Author
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Po-Chun Hsu and Xiuqiang Li
- Subjects
Multidisciplinary ,Photon ,Materials science ,Radiative cooling ,business.industry ,Optoelectronics ,business - Abstract
Personal thermal management offers a path to reduce climate control energy use
- Published
- 2020
20. Thermal Management in Nanofiber-Based Face Mask
- Author
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Jinwei Xu, Guangmin Zhou, Yi Cui, Lili Cai, Po-Chun Hsu, Jiangyan Wang, Ankun Yang, Rufan Zhang, and Hongxia Wang
- Subjects
Materials science ,Radiative cooling ,Bioengineering ,Nanotechnology ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Coating ,General Materials Science ,Fiber ,business.industry ,Nanoporous ,Mechanical Engineering ,Thermal comfort ,General Chemistry ,Particulates ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Nanofiber ,engineering ,Optoelectronics ,0210 nano-technology ,business ,Layer (electronics) - Abstract
Face masks are widely used to filter airborne pollutants, especially when particulate matter (PM) pollution has become a serious concern to public health. Here, the concept of thermal management is introduced into face masks for the first time to enhance the thermal comfort of the user. A system of nanofiber on nanoporous polyethylene (fiber/nanoPE) is developed where the nanofibers with strong PM adhesion ensure high PM capture efficiency (99.6% for PM2.5) with low pressure drop and the nanoPE substrate with high-infrared (IR) transparency (92.1%, weighted based on human body radiation) results in effective radiative cooling. We further demonstrate that by coating nanoPE with a layer of Ag, the fiber/Ag/nanoPE mask shows a high IR reflectance (87.0%) and can be used for warming purposes. These multifunctional face mask designs can be explored for both outdoor and indoor applications to protect people from PM pollutants and simultaneously achieve personal thermal comfort.
- Published
- 2017
21. Direct/Alternating Current Electrochemical Method for Removing and Recovering Heavy Metal from Water Using Graphene Oxide Electrode
- Author
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Po-Chun Hsu, Jinwei Xu, Jing Tang, Jie Zhao, Chong Liu, Yi Cui, Jin Xie, Jie Sun, Kai Liu, Tong Wu, Ziwen Ye, and Dingchang Lin
- Subjects
Pollution ,Materials science ,Graphene ,media_common.quotation_subject ,Direct current ,General Engineering ,Oxide ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,law.invention ,Industrial wastewater treatment ,chemistry.chemical_compound ,Adsorption ,Chemical engineering ,chemistry ,law ,Electrode ,General Materials Science ,0210 nano-technology ,media_common - Abstract
Treatment of heavy-metal pollution in both point-of-use water and industrial wastewater is critical in protecting human health and the environment. Current methods for heavy-metal treatment in both sources have limitations. For point-of-use water, current methods usually suffer from limited capacity and difficulties in spontaneously removing multiple heavy metals. For industrial wastewater, current methods greatly reduce the value of heavy metal by precipitating them as sludge which requires further treatment. Here we developed an electrochemical method that can treat both low-concentration and high-concentration heavy-metal pollution using either direct current (DC) or alternating current (AC) electrodeposition with graphene-oxide-modified carbon felt electrode (CF-GO). The graphene oxide provides a high density of surface functional groups to assist the electrodeposition. The electrodeposition method showed 2 orders of magnitude higher capacity (>29 g heavy metal for 1 g of graphene oxide) compared with traditional adsorption methods. For low levels of heavy-metal pollution in point-of-use water, DC electrodeposition with a CF-GO electrode can reduce single heavy-metal ion pollution (Cu, Cd, and Pb) as well as multiple ion mixtures to below safe water drinking levels. This method can tolerate a much wider range of heavy-metal pollution in point-of-use water than traditional adsorption methods. For high-level pollution in industrial wastewater, AC electrodeposition can recover >99.9% heavy-metal ions. By tuning the AC frequency and voltage, the electrodeposition method can further selectively recover Cu, Cd, and Pb separately, which adds values to the heavy-metal removal process.
- Published
- 2019
22. Trap-assisted tunnelling and Shockley-Read-Hall lifetime of extended defects in In.53Ga.47As p+n junction
- Author
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M.M. Heyns, Nadine Collaert, Robert Langer, A. Alian, Geert Eneman, C Merckling, Eddy Simoen, and Po-Chun Hsu
- Subjects
History ,Materials science ,Technology and Engineering ,Field (physics) ,Condensed matter physics ,Field dependence ,Epitaxy ,Crystallographic defect ,Computer Science Applications ,Education ,Physics and Astronomy ,Density of states ,Metalorganic vapour phase epitaxy ,p–n junction ,Quantum tunnelling - Abstract
Several In.53Ga.47As p+n junctions with various extended defect densities (EDDs) have been grown by metalorganic vapor phase epitaxy (MOVPE), by carefully controlling the growth conditions. After fabrication, T-dependent J-V, C-V and double DLTS (DDLTS) are performed to extract the electrical field dependence of the extended defect levels. From this characterization, it is derived that the extended defects dominate the electrical field enhancement factor Г regardless of the value of the EDD and significantly increases the leakage current under reverse bias (i.e., decrease the Shockley-Read-Hall lifetime). These impacts are strongly connected to a “band-like” density of states of extended defects E2 at EC-0.32 eV by comparing the DDLTS and T-dependent J-V characteristics. On the other hand, the reference sample (without EDs) surprisingly exhibits an even stronger field dependence with lower leakage current. Nevertheless, no straightforward candidate point defects can be found in this sample and the possible explanation are discussed.
- Published
- 2019
23. Deep levels in metal-oxide-semiconductor capacitors fabricated on n-type In0.53Ga0.47As lattice matched to InP substrates
- Author
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Alireza Alian, Eddy Simoen, S. El Kazzi, Po-Chun Hsu, and Wang Chenxia
- Subjects
Materials science ,InGaAs ,Annealing (metallurgy) ,INTERFACE STATES ,Oxide ,antisite defects ,RELAXATION ,02 engineering and technology ,Epitaxy ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,MOS capacitor ,Gate oxide ,law ,0103 physical sciences ,Materials Chemistry ,Wafer ,Electrical and Electronic Engineering ,III-V ,010302 applied physics ,DLTS ,business.industry ,EL2 ,TRAPS ,DEFECTS ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Capacitor ,chemistry ,Physics and Astronomy ,Optoelectronics ,0210 nano-technology ,business ,Forming gas ,EMISSION ,TRANSIENT SPECTROSCOPY ,CONSTANT-CAPACITANCE ,SI-SIO2 STRUCTURES ,Molecular beam epitaxy - Abstract
In this work, deep levels present in n-type In0.53Ga0.47As hetero-epitaxial layers grown lattice-matched on n-type InP substrates by molecular beam epitaxy have been studied by deep-level transient spectroscopy (DLTS). Metal–oxide–semiconductor capacitors are employed, based on an Al2O3 gate oxide. It is shown that a single, near mid-gap electron trap dominates the DLT-spectra, whatever the surface pre-or post-gate oxide deposition treatment. At the same time, it is shown that the deep level parameters vary significantly from capacitor to capacitor and from wafer to wafer. Only after Forming Gas Annealing, a stable value for the activation energy of 0.39 ± 0.01 eV is obtained. These results are tentatively interpreted in terms of antisite defects in the epitaxial layer, which form a family of related complexes with close deep-level parameters.
- Published
- 2019
24. Rapid water disinfection using vertically aligned MoS2 nanofilms and visible light
- Author
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Yayuan Liu, Kai Yan, Kimberly M. Parker, Peter A. Maraccini, Hyun-Wook Lee, Chong Liu, Dingchang Lin, Hongtao Yuan, Desheng Kong, Haotian Wang, Shuang Wang, Po-Chun Hsu, Alexandria B. Boehm, and Yi Cui
- Subjects
Materials science ,Biomedical Engineering ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Photocatalysis ,General Materials Science ,Electrical and Electronic Engineering ,Water disinfection ,0210 nano-technology ,Visible spectrum - Abstract
Few-layered, vertically aligned MoS2 films can efficiently harvest visible light for photocatalytic water disinfection, allowing >99.999% bacteria to be rapidly inactivated.
- Published
- 2016
25. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide)
- Author
-
Hye Ryoung Lee, Yi Cui, Yayuan Liu, Po-Chun Hsu, Wei Liu, Dingchang Lin, and Kai Liu
- Subjects
Materials science ,Crystallization of polymers ,Oxide ,Bioengineering ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,law ,Polymer chemistry ,Ionic conductivity ,General Materials Science ,Ceramic ,Crystallization ,chemistry.chemical_classification ,Ethylene oxide ,Mechanical Engineering ,General Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.
- Published
- 2015
26. A Deep Level Transient Spectroscopy Study of Hole Traps in GexSe1−x-based Layers for Ovonic Threshold Switching Selectors
- Author
-
Po-Chun Hsu, P. Carolan, Hugo Bender, Romain Delhougne, Andre Stesmans, Ludovic Goux, Gouri Sankar Kar, Eddy Simoen, and Dennis Lin
- Subjects
Materials science ,Deep-level transient spectroscopy ,business.industry ,Optoelectronics ,business ,Electronic, Optical and Magnetic Materials - Published
- 2020
27. Green Treatment of Phosphate from Wastewater Using a Porous Bio-Templated Graphene Oxide/MgMn-Layered Double Hydroxide Composite
- Author
-
Po-Chun Hsu, Min-Chao Chang, Yu-Sheng Huang, Nyan-Hwa Tai, Yan-Cheng Lin, Horng-Tay Jeng, Yi-Ting Lai, Chi-Young Lee, Chin-Hsuan Chen, and Lih-Juann Chen
- Subjects
Natural Material ,0301 basic medicine ,Materials science ,Oxide ,chemistry.chemical_element ,02 engineering and technology ,Article ,law.invention ,03 medical and health sciences ,chemistry.chemical_compound ,Adsorption ,law ,Desorption ,Calcination ,lcsh:Science ,Green Chemistry ,Multidisciplinary ,Graphene ,Phosphorus ,021001 nanoscience & nanotechnology ,Phosphate ,Environmental Chemical Engineering ,030104 developmental biology ,chemistry ,Chemical engineering ,Hydroxide ,lcsh:Q ,0210 nano-technology - Abstract
Summary Excessive phosphorus in water is the primary culprit for eutrophication, which causes approximately $2.2 billion annual economic loss in the United States. This study demonstrates a phosphate-selective sustainable method by adopting Garcinia subelliptica leaves as a natural bio-template, where MgMn-layered double hydroxide (MgMn-LDH) and graphene oxide (GO) can be grown in situ to obtain L-GO/MgMn-LDH. After calcination, the composite shows a hierarchical porous structure and selective recognition of phosphate, which achieves significantly high and recyclable selective phosphate adsorption capacity and desorption rate of 244.08 mg-P g−1 and 85.8%, respectively. The detail variation of LDHs during calcination has been observed via in situ transmission electron microscope (TEM). Moreover, the roles in facilitating phosphate adsorption and antimicrobial ability of chemical constituents in Garcinia subelliptica leaves, biflavonoids, and triterpenoids have been investigated. These results indicate the proposed bio-templated adsorbent is practical and eco-friendly for phosphorus sustainability in commercial wastewater treatment., Graphical Abstract, Highlights • A natural bio-template provides hierarchical porous structure • The variation of nanostructure during thermal process is discussed in detail • The composite shows high sorption, selectivity, stability, and sustainability, Environmental Chemical Engineering; Green Chemistry; Natural Material
- Published
- 2020
28. Erratum: Electrical Activity of Extended Defects in Relaxed InxGa1−xAs Hetero-Epitaxial Layers [ ECS J. Solid State Sci. Technol., 9, 033001 (2020)]
- Author
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Han Han, Geert Eneman, P. Carolan, F. Seidel, Po-Chun Hsu, M.M. Heyns, Clement Merckling, Niamh Waldron, Nadine Collaert, Alireza Alian, Hugo Bender, Cor Claeys, Yves Mols, and Eddy Simoen
- Subjects
X-ray absorption spectroscopy ,Materials science ,Condensed matter physics ,Solid-state ,Epitaxy ,Electronic, Optical and Magnetic Materials - Published
- 2020
29. In-situ grown hollow Fe3O4 onto graphene foam nanocomposites with high EMI shielding effectiveness and thermal conductivity
- Author
-
Haoming Fang, Yanjuan Ren, Haichang Guo, Yiran Hu, Po-Chun Hsu, and Shu-Lin Bai
- Subjects
Materials science ,Nanocomposite ,Polydimethylsiloxane ,Graphene foam ,Composite number ,General Engineering ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Thermal conductivity ,chemistry ,Thermal ,Ceramics and Composites ,Composite material ,0210 nano-technology ,Electrical conductor ,Power density - Abstract
With the increasing packaging density and multi-functionality, thermal management and electromagnetic pollution in electronic devices are crucial. In this work, we propose a novel method to in-situ grow hollow Fe3O4 sphere (h-Fe3O4, inner and outer diameter of 870 nm and 975 nm, respectively) onto three-dimensional graphene foam (GF) surface and then filled it with polydimethylsiloxane (PDMS) to fabricate nanocomposites with high electromagnetic interference shielding effectiveness (70.37 dB from 8.2 to 12.4 GHz) and thermal conductivity (28.12 ± 1.212 W m−1 K−1) at room temperature. Moreover, conductive networks inside composites show super-flexible performance with high electrical conductivity (84.02 ± 8.385 S cm−1). The effect of in-situ growth hollow Fe3O4 spheres in the enhancement of EMI SE has been demonstrated via comparing with different contents, morphologies and preparation processing. Besides, the mechanism of thermal conductivity has been investigated by FEM simulation and theoretical modeling. Finally, the usage of GF/h-Fe3O4/PDMS composites as thermal interface materials (TIMs) for chip cooling is proved to be successful, and the corresponding temperature under usage power density is accurately predicted. These comprehensive properties of GF/h-Fe3O4/PDMS composite open a potential application for next-generation TIMs in chip packaging.
- Published
- 2020
30. Electrical Activity of Extended Defects in Relaxed InxGa1−xAs Hetero-Epitaxial Layers
- Author
-
Clement Merckling, Hugo Bender, Po-Chun Hsu, Han Han, Yves Mols, C. Claeys, Niamh Waldron, Nadine Collaert, A. Alian, Geert Eneman, P. Carolan, M.M. Heyns, Eddy Simoen, and F. Seidel
- Subjects
Reduction (complexity) ,X-ray absorption spectroscopy ,Materials science ,Silicon ,chemistry ,business.industry ,Optoelectronics ,chemistry.chemical_element ,business ,Epitaxy ,Electronic, Optical and Magnetic Materials - Published
- 2020
31. Do we have to worry about extended defects in high-mobility materials?
- Author
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Eddy Simoen, Yves Mols, Geert Eneman, Mark Heyns, Bernadette Kunert, Robert Langer, Nadine Collaert, Niamh Waldron, Liang He, Cor Claeys, and Po-Chun Hsu
- Subjects
010302 applied physics ,Threading dislocations ,Materials science ,Silicon ,business.industry ,chemistry.chemical_element ,Noise spectroscopy ,01 natural sciences ,chemistry ,0103 physical sciences ,Optoelectronics ,business ,Analysis method ,Transient spectroscopy ,Communication channel - Abstract
An overview is given on how to tackle the question of the electrical activity of extended defects which are inevitably present in hetero-epitaxial III-V layers on silicon. Analysis methods are described which rely on simple device structures containing a specific type of extended defect (here, threading dislocations). Applying the same methods to real scaled FinFETs is rather challenging. Instead Generation-Recombination noise spectroscopy provides data that can be compared with other more standard techniques, like Deep-Level Transient Spectroscopy (DLTS) in order to identify the presence of an electrically active extended defect in the channel material.
- Published
- 2018
32. A dual-mode textile for human body radiative heating and cooling
- Author
-
Arun Majumdar, Lili Cai, Jin Xie, Yi Cui, Chun-Lan Wu, Peter B. Catrysse, Shang Zhai, Chong Liu, Yucan Peng, Alex Y. Song, Shanhui Fan, Ze Zhang, Po-Chun Hsu, and Kai Liu
- Subjects
Materials science ,Textile ,Infrared ,Infrared Rays ,Mechanical engineering ,02 engineering and technology ,Heat transfer coefficient ,010402 general chemistry ,01 natural sciences ,Body Temperature ,Nanopores ,Wearable Electronic Devices ,Emissivity ,Humans ,Research Articles ,Common emitter ,Multidisciplinary ,business.industry ,Textiles ,Temperature ,Thermal comfort ,SciAdv r-articles ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Applied Sciences and Engineering ,Polyethylenes ,0210 nano-technology ,business ,Layer (electronics) ,Research Article - Abstract
Dual-mode textiles made of nanoPE provide both cooling and heating, which helps humans adapt to larger temperature changes., Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount of energy to keep the ambient temperature constant. To expand the ambient temperature range while maintaining human thermal comfort, the concept of personal thermal management has been recently demonstrated in heating and cooling textiles separately through human body infrared radiation control. Realizing these two opposite functions within the same textile would represent an exciting scientific challenge and a significant technological advancement. We demonstrate a dual-mode textile that can perform both passive radiative heating and cooling using the same piece of textile without any energy input. The dual-mode textile is composed of a bilayer emitter embedded inside an infrared-transparent nanoporous polyethylene (nanoPE) layer. We demonstrate that the asymmetrical characteristics of both emissivity and nanoPE thickness can result in two different heat transfer coefficients and achieve heating when the low-emissivity layer is facing outside and cooling by wearing the textile inside out when the high-emissivity layer is facing outside. This can expand the thermal comfort zone by 6.5°C. Numerical fitting of the data further predicts 14.7°C of comfort zone expansion for dual-mode textiles with large emissivity contrast.
- Published
- 2017
33. Effect of Chemical Structure on Polymer-Templated Growth of Graphitic Nanoribbons
- Author
-
Hu Young Jeong, Nan Liu, Yi Cui, Kwanpyo Kim, Po-Chun Hsu, and Zhenan Bao
- Subjects
chemistry.chemical_classification ,Electron mobility ,Vinyl alcohol ,Materials science ,Band gap ,Graphene ,General Engineering ,General Physics and Astronomy ,Nanotechnology ,Polymer ,Electrospinning ,law.invention ,chemistry.chemical_compound ,Crystallinity ,chemistry ,law ,General Materials Science ,Polystyrene - Abstract
Graphene nanoribbon (GNR) is an important candidate for future nanoelectronics due to its high carrier mobility and dimension-controlled band gap. Polymer-templated growth is a promising method toward high quality and massive production of GNRs. However, the obtained GNRs so far are still quite defective. In order to rationally control the crystallinity of the synthesized GNRs, herein we systematically investigate the effect of polymer chemical structure on their templated growth of GNRs. We studied the morphology/dimensions, composition, graphitization degree, and electrical conductivity of GNRs derived from four different types of electrospun polymers. The four polymers polystyrene (PS), poly(vinyl alcohol) (PVA), polyvinylphenol (PVP), and Novolac (a phenolic resin) are chosen to investigate the effect of metal binding and the effect of aromatic moieties. We found that metal-binding functional groups are crucial for obtaining uniform and continuous GNRs. On the other hand, a polymer with aromatic moieties leads to a higher sp(2) percentage in the resulting GNRs, showing a higher graphitization degree and electrical conductivity.
- Published
- 2015
34. Roll-to-Roll Encapsulation of Metal Nanowires between Graphene and Plastic Substrate for High-Performance Flexible Transparent Electrodes
- Author
-
Jinxiong Wu, Qin Xie, Lei Liao, Guanchu Chen, Zhongfan Liu, Yunfan Guo, Po-Chun Hsu, Zhawulie Ayitimuda, Mahaya Aisijiang, Yi Cui, Bananakere Nanjegowda Chandrashekar, Bing Deng, Hailin Peng, Yu Zhou, and Li Lin
- Subjects
Materials science ,Graphene ,Mechanical Engineering ,Nanowire ,Bioengineering ,General Chemistry ,Chemical vapor deposition ,Condensed Matter Physics ,law.invention ,Roll-to-roll processing ,law ,Transmittance ,General Materials Science ,Composite material ,Sheet resistance ,FOIL method ,Transparent conducting film - Abstract
Transparent conductive film on plastic substrate is a critical component in low-cost, flexible, and lightweight optoelectronics. Industrial-scale manufacturing of high-performance transparent conductive flexible plastic is needed to enable wide-ranging applications. Here, we demonstrate a continuous roll-to-roll (R2R) production of transparent conductive flexible plastic based on a metal nanowire network fully encapsulated between graphene monolayer and plastic substrate. Large-area graphene film grown on Cu foil via a R2R chemical vapor deposition process was hot-laminated onto nanowires precoated EVA/PET film, followed by a R2R electrochemical delamination that preserves the Cu foil for reuse. The encapsulated structure minimized the resistance of both wire-to-wire junctions and graphene grain boundaries and strengthened adhesion of nanowires and graphene to plastic substrate, resulting in superior optoelectronic properties (sheet resistance of ∼8 Ω sq(-1) at 94% transmittance), remarkable corrosion resistance, and excellent mechanical flexibility. With these advantages, long-cycle life flexible electrochromic devices are demonstrated, showing up to 10000 cycles.
- Published
- 2015
35. Polymer Nanofiber-Guided Uniform Lithium Deposition for Battery Electrodes
- Author
-
Po-Chun Hsu, Weiyang Li, Guangyuan Zheng, Chong Liu, Kai Yan, Yi Cui, Nian Liu, Hong-Bin Yao, Zheng Liang, and Steven Chu
- Subjects
Battery (electricity) ,Materials science ,Lithium vanadium phosphate battery ,Mechanical Engineering ,Inorganic chemistry ,Polyacrylonitrile ,chemistry.chemical_element ,Bioengineering ,General Chemistry ,Electrolyte ,Condensed Matter Physics ,Anode ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Nanofiber ,Electrode ,General Materials Science ,Lithium - Abstract
Lithium metal is one of the most promising candidates as an anode material for next-generation energy storage systems due to its highest specific capacity (3860 mAh/g) and lowest redox potential of all. The uncontrolled lithium dendrite growth that causes a poor cycling performance and serious safety hazards, however, presents a significant challenge for the realization of lithium metal-based batteries. Here, we demonstrate a novel electrode design by placing a three-dimensional (3D) oxidized polyacrylonitrile nanofiber network on top of the current collector. The polymer fiber with polar surface functional groups could guide the lithium ions to form uniform lithium metal deposits confined on the polymer fiber surface and in the 3D polymer layer. We showed stable cycling of lithium metal anode with an average Coulombic efficiency of 97.4% over 120 cycles in ether-based electrolyte at a current density of 3 mA/cm(2) for a total of 1 mAh/cm(2) of lithium.
- Published
- 2015
36. A high tap density secondary silicon particle anode fabricated by scalable mechanical pressing for lithium-ion batteries
- Author
-
Chong Liu, Hye Ryoung Lee, Jie Zhao, Nian Liu, Po-Chun Hsu, Haotian Wang, Zhenda Lu, Dingchang Lin, and Yi Cui
- Subjects
Fabrication ,Materials science ,Silicon ,Renewable Energy, Sustainability and the Environment ,chemistry.chemical_element ,Nanotechnology ,Carbon nanotube ,Pollution ,Lithium-ion battery ,Electrical contacts ,law.invention ,Anode ,Nanomaterials ,Nuclear Energy and Engineering ,chemistry ,Chemical engineering ,law ,Environmental Chemistry ,Lithium - Abstract
Much progress has been made in developing high capacity lithium ion battery electrode materials such as silicon anodes. With the powerful nanomaterial design approach, cycle life of silicon anodes has been increased significantly. However, nanomaterials have three major issues to be addressed, including severe side reactions due to a large surface area, low tap density and poor scalability. Nanostructured Si secondary clusters (nano-Si SC) are promising for reducing side reactions and increasing tap density, yet the scalability and tap density could still be further improved. Here, we propose a mechanical approach for SC fabrication to address all the problems. With the mechanical approach, >20 g of nano-Si SC per batch was produced even at our university lab scale, with >95% yield. Moreover, much denser packing of nanostructures can be achieved (1.38 g cm−3, pellet form), which gives much higher tap density (0.91 g cm−3, powder form) and better electrical contact. Accordingly, over 95% of initial capacity is retained after 1400 cycles at 1C, with an average specific capacity of ∼1250 mA h g−1. Stable cycling with >2 mg cm−2 of areal mass loading (∼3.5 mA h cm−2) is obtained. After uniformly integrating carbon nanotubes (CNTs) into SCs, intracluster electrical conductivity is further improved. As a result, notably enhanced rate capability is attained, with a high reversible specific capacity of ∼1140 mA h g−1 and ∼880 mA h g−1 at 2C and 4C, respectively.
- Published
- 2015
37. Personal Thermal Management by Metallic Nanowire-Coated Textile
- Author
-
Chong Liu, Po-Chun Hsu, Alex J. Welch, Hye Ryoung Lee, Yi Cui, Tom Zhao, Xing Xie, and Xiaoge Liu
- Subjects
Textile ,Materials science ,Infrared ,business.industry ,Mechanical Engineering ,Nanowire ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Engineering physics ,Durability ,Thermal ,General Materials Science ,Composite material ,business ,Joule heating ,Porosity ,Electrical conductor - Abstract
Heating consumes large amount of energy and is a primary source of greenhouse gas emission. Although energy-efficient buildings are developing quickly based on improving insulation and design, a large portion of energy continues to be wasted on heating empty space and nonhuman objects. Here, we demonstrate a system of personal thermal management using metallic nanowire-embedded cloth that can reduce this waste. The metallic nanowires form a conductive network that not only is highly thermal insulating because it reflects human body infrared radiation but also allows Joule heating to complement the passive insulation. The breathability and durability of the original cloth is not sacrificed because of the nanowires' porous structure. This nanowire cloth can efficiently warm human bodies and save hundreds of watts per person as compared to traditional indoor heaters.
- Published
- 2014
38. Thermal stability of grain structure and material properties in an annealing twinned Ag–4Pd alloy wire
- Author
-
Hsin-Jung Lin, Tung-Han Chuang, Po-Chun Hsu, Yen-Lin Huang, Jun-Der Lee, Hsing-Hua Tsai, Yu-Yun Shiue, Chien-Hsun Chuang, and Fuh-Sheng Shieu
- Subjects
Wire bonding ,Materials science ,Annealing (metallurgy) ,Mechanical Engineering ,Metallurgy ,Alloy ,Metals and Alloys ,engineering.material ,Grain size ,Grain growth ,Mechanics of Materials ,Electrical resistivity and conductivity ,Materials Chemistry ,engineering ,Elongation ,Material properties - Abstract
An annealing twinned Ag–4Pd binary alloy wire has been produced as an alternate material for a previously developed Ag–8Au–3Pd ternary alloy wire to meet requirements for high electrical conductivity and low cost. The electrical resistivity of this annealing twinned Ag-alloy bonding wire decreased drastically from the original value of 3.5 μΩ cm to about 2.9 μΩ cm after aging at 600 °C for 30 min. The decrease in electrical resistivity became moderate with longer aging times. In contrast to the apparent increase in grain size in a conventional Ag–4Pd wire during aging at 600 °C for various times, the grains in this annealing twinned wire grew much more slowly. The breaking load and elongation of this annealing twinned Ag–4Pd wire are also higher than those of conventional wire. The conventional grained Ag–4Pd wire has a slightly higher electrical resistivity of 3.7 μΩ cm than that of annealing twinned wire. However, the more rapid grain growth in the conventional grained Ag–4Pd wire led to a lower electrical resistivity than that of annealing twinned wire during aging process.
- Published
- 2014
39. Warming up human body by nanoporous metallized polyethylene textile
- Author
-
Yi Cui, Shanhui Fan, Chenyu Zhou, Peter B. Catrysse, Lili Cai, Yayuan Liu, Chong Liu, Ankun Yang, Chenxing Zhou, Yucan Peng, Po-Chun Hsu, Jun Chen, Alex Y. Song, and Peilin Wu
- Subjects
Global energy ,Materials science ,Textile ,Science ,General Physics and Astronomy ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Affordable and Clean Energy ,Emissivity ,lcsh:Science ,Multidisciplinary ,Nanoporous ,business.industry ,General Chemistry ,Polyethylene ,021001 nanoscience & nanotechnology ,Engineering physics ,0104 chemical sciences ,chemistry ,Thermal radiation ,Heating energy ,lcsh:Q ,0210 nano-technology ,business ,Layer (electronics) - Abstract
Space heating accounts for the largest energy end-use of buildings that imposes significant burden on the society. The energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, we demonstrate a nanophotonic structure textile with tailored infrared (IR) property for passive personal heating using nanoporous metallized polyethylene. By constructing an IR-reflective layer on an IR-transparent layer with embedded nanopores, the nanoporous metallized polyethylene textile achieves a minimal IR emissivity (10.1%) on the outer surface that effectively suppresses heat radiation loss without sacrificing wearing comfort. This enables 7.1 °C decrease of the set-point compared to normal textile, greatly outperforming other radiative heating textiles by more than 3 °C. This large set-point expansion can save more than 35% of building heating energy in a cost-effective way, and ultimately contribute to the relief of global energy and climate issues., Energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, the authors show a nanophotonic structure textile with tailored infrared property for passive personal heating using nanoporous metallized polyethylene.
- Published
- 2017
40. Compound-induced changes in thermal, structural and optical properties of indium–gallium–zinc oxides prepared by sol–gel method
- Author
-
Po-chun Hsu, Guan-ting Chen, Yutaka Sawada, and Keh-Moh Lin
- Subjects
Thermogravimetric analysis ,Materials science ,Thermal decomposition ,Mineralogy ,chemistry.chemical_element ,General Chemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,law.invention ,Biomaterials ,Crystallinity ,Chemical engineering ,chemistry ,law ,Materials Chemistry ,Ceramics and Composites ,Crystallization ,Gallium ,Indium ,Sol-gel - Abstract
In this study, IZO/IGZO powders and films of different composition ratios were fabricated by sol–gel method. The influences of the composition ratio on the decomposition temperature, crystallization behavior, structural and optical properties of multi-component oxides were thoroughly examined. Thermogravimetric/differential scanning calorimetric results revealed that in contrast to zinc and indium oxides, the high crystallization temperature and low crystallinity of gallium oxide were attributed to the high dehydroxylation temperature of gallium hydroxide, which led to the high decomposition and crystallization temperatures of IGZO compound. The XRD analysis of the IGZO films confirmed that the addition of Ga amount made the films turn into amorphous easily. However, TEM analysis suggested that the IZO film (In:Zn = 1:2) and the IGZO (In:Ga:Zn = 1:1:1) film consisted of short-range-order nanostructure although the selected area diffraction of both samples indicated that they are amorphous. The transmittance measurements agreed well with the XRD results; that is, the band gaps of the IZO/IGZO films obviously depend on the composition ratio and are closely related to the change of the structural properties.
- Published
- 2014
41. Air-stable and freestanding lithium alloy/graphene foil as an alternative to lithium metal anodes
- Author
-
Jie Zhao, Yuzhang Li, Guangmin Zhou, Jiangyan Wang, Hui-Ming Cheng, Jin Xie, Kai Yan, Po-Chun Hsu, Yi Cui, Yang Jin, Kai Liu, and Lei Liao
- Subjects
Materials science ,Alloy ,Biomedical Engineering ,chemistry.chemical_element ,Bioengineering ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Electrochemical cell ,law.invention ,law ,General Materials Science ,Electrical and Electronic Engineering ,Composite material ,FOIL method ,Graphene ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Cathode ,0104 chemical sciences ,Anode ,chemistry ,Electrode ,engineering ,Lithium ,0210 nano-technology - Abstract
Developing high-capacity anodes is a must to improve the energy density of lithium batteries for electric vehicle applications. Alloy anodes are one promising option, but without pre-stored lithium, the overall energy density is limited by the low-capacity lithium metal oxide cathodes. Recently, lithium metal has been revived as a high-capacity anode, but faces several challenges owing to its high reactivity and uncontrolled dendrite growth. Here, we show a series of Li-containing foils inheriting the desirable properties of alloy anodes and pure metal anodes. They consist of densely packed Li
- Published
- 2016
42. The impact of extended defects on the generation and recombination lifetime in n type In.53Ga.47As
- Author
-
Alireza Alian, Han Han, Marc Heyns, Po-Chun Hsu, Geert Eneman, Eddy Simoen, Clement Merckling, Yves Mols, and Nadine Collaert
- Subjects
010302 applied physics ,Materials science ,Photoluminescence ,Deep-level transient spectroscopy ,Acoustics and Ultrasonics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Crystallographic defect ,Molecular physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,0103 physical sciences ,Dislocation ,0210 nano-technology ,p–n junction ,Spectroscopy ,Recombination ,Diode - Abstract
The relationship between the Threading Dislocation Density (TDD), the generation (τg) and recombination lifetime (τr) in relaxed n-type In.53Ga.47As is investigated for a series of p+n junction diodes, containing an TDD ranging from 105 to 1010 cm-2. The TDs are generated intentionally by lattice-misfit growth on Semi-Insulating (SI) InP and GaAs substrates. The lifetimes have been extracted from diode Current-Voltage (I-V) and Photoluminescence (PL) analysis showing that TDDs affect their values above a density of about 1×107 cm-2 (τg,E~0) and about 1×108 cm-2 (τr and τPL), which can be well-explained by the charged dislocation cylinder model. In addition, a detailed comparison between the results from Deep Level Transient Spectroscopy (DLTS) and from the diode characterization is performed, showing that the responsible G/R center shifts toward mid-gap in In.53Ga.47As and transfers from a native point defect (PD1) to a TD (E2/H1). Finally, the classical concept of generation lifetime and recombination lifetime in terms of dislocations is discussed based on the results.
- Published
- 2019
43. Observation of the Stacking Faults in In 0.53 Ga 0.47 As by Electron Channeling Contrast Imaging
- Author
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Geert Eneman, Yves Mols, Clement Merckling, Han Han, Eddy Simoen, Marc Heyns, Nadine Collaert, and Po-Chun Hsu
- Subjects
Diffraction ,Technology ,InGaAs ,Materials Science ,MODELS ,DISLOCATION FORMATION ,Stacking ,Materials Science, Multidisciplinary ,electron channeling contrast imaging ,02 engineering and technology ,misfit dislocations ,01 natural sciences ,LAYERS ,Physics, Applied ,law.invention ,law ,0103 physical sciences ,Microscopy ,Materials Chemistry ,Electrical and Electronic Engineering ,stacking faults ,010302 applied physics ,Science & Technology ,atomic force microscopy ,Condensed matter physics ,Physics ,MICROSCOPY ,Surfaces and Interfaces ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Crystallographic defect ,heteroepitaxy ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Physics, Condensed Matter ,Electron diffraction ,Transmission electron microscopy ,Physical Sciences ,Electron microscope ,0210 nano-technology ,Burgers vector - Abstract
The observation and interpretation of Frank stacking faults, Shockley stacking faults, Lomer dislocations, and 60 degrees misfit dislocations, which have similar line shapes in the (001) In0.53Ga0.47As crystalline surface, are performed with the electron channeling contrast imaging (ECCI) technique. To minimize the backscattered electron (BSE) contrast that resulted from the surface morphology, a relatively flat region is first selected and compared with an atomic force microscopy (AFM) image and then, subsequently, examining ECCI with transmission electron microscopy (TEM)-like invisibility criteria. By orthogonally choosing the diffraction vector g between (220) and (2-20), misfit dislocations seem to be always visible but partially faint in the g parallel to the line direction on the surface. With respect to the image contrast, Frank stacking faults and Lomer dislocations are likely to be completely invisible for parallel g. The criteria are further confirmed by cross-sectional TEM analysis, which shows a preferred homogeneous surface nucleation.
- Published
- 2019
44. Are Extended Defects a Show Stopper for Future III-V CMOS Technologies
- Author
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C. Claeys, Yves Mols, Liang He, Geert Eneman, M.M. Heyns, Niamh Waldron, Robert Langer, Po-Chun Hsu, Nadine Collaert, and Eddy Simoen
- Subjects
History ,Materials science ,Deep-level transient spectroscopy ,Si substrate ,CMOS ,Infrasound ,Electrical performance ,Defect engineering ,Spectroscopy ,Engineering physics ,Computer Science Applications ,Education ,Process conditions - Abstract
The paper briefly reviews some of the present-day state-of-the art III-V devices processed on a Si platform reported in the literature, before addressing defect engineering aspects for III-V processing on a Si substrate from both a structural and electrical performance perspective. The identification of the extended defects will be illustrated by some case studies based on leakage current and lifetime investigations, Deep Level Transient Spectroscopy (DLTS) analysis and low frequency noise spectroscopy. Information on the basic defect parameters can be used as input for TCAD simulation of the electrical device performance, enabling a further optimization of the materials’ growth and process conditions.
- Published
- 2019
45. Nanofiber Air Filters with High-Temperature Stability for Efficient PM2.5 Removal from the Pollution Sources
- Author
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Nian Liu, Yingying Lu, Rufan Zhang, Yongcai Qiu, Po-Chun Hsu, Chong Liu, Jinsong Zhang, Hye Ryoung Lee, Steven Chu, Yi Cui, and Chaofan Zhang
- Subjects
Pollution ,Pressure drop ,Materials science ,Mechanical Engineering ,media_common.quotation_subject ,Analytical chemistry ,Bioengineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Filter (aquarium) ,Flux (metallurgy) ,Nanofiber ,General Materials Science ,Thermal stability ,Composite material ,0210 nano-technology ,Polyimide ,Air filter ,media_common - Abstract
Here, we developed high-efficiency (>99.5%) polyimide-nanofiber air filters for the high temperature PM2.5 removal. The polyimide nanofibers exhibited high thermal stability, and the PM2.5 removal efficiency was kept unchanged when temperature ranged from 25–370 °C. These filters had high air flux with very low pressure drop. They could continuously work for >120 h for PM2.5 index >300. A field-test showed that they could effectively remove >99.5% PM particles from car exhaust at high temperature.
- Published
- 2016
46. Roll-to-Roll Transfer of Electrospun Nanofiber Film for High-Efficiency Transparent Air Filter
- Author
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Yayuan Liu, Po-Chun Hsu, Kai Liu, Chong Liu, Rufan Zhang, Jinwei Xu, and Yi Cui
- Subjects
Materials science ,Mechanical Engineering ,Bioengineering ,02 engineering and technology ,General Chemistry ,Substrate (printing) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electrospinning ,0104 chemical sciences ,law.invention ,Roll-to-roll processing ,Filter (video) ,law ,Nanofiber ,Transmittance ,General Materials Science ,Composite material ,0210 nano-technology ,Filtration ,Air filter - Abstract
Particulate matter (PM) pollution in air has become a serious environmental issue calling for new type of filter technologies. Recently, we have demonstrated a highly efficient air filter by direct electrospinning of polymer fibers onto supporting mesh although its throughput is limited. Here, we demonstrate a high throughput method based on fast transfer of electrospun nanofiber film from roughed metal foil to a receiving mesh substrate. Compared with the direct electrospinning method, the transfer method is 10 times faster and has better filtration performance at the same transmittance, owing to the uniformity of transferred nanofiber film (>99.97% removal of PM2.5 at ∼73% of transmittance). With these advantages, large area freestanding nanofiber film and roll-to-roll production of air filter are demonstrated.
- Published
- 2016
47. Fast and reversible thermoresponsive polymer switching materials for safer batteries
- Author
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Yuzhang Li, Chao Wang, Jeffrey Lopez, Jia Liu, Zhenan Bao, Nan Liu, Zheng Chen, John W. F. To, Sean C. Andrews, Po-Chun Hsu, and Yi Cui
- Subjects
chemistry.chemical_classification ,Materials science ,Thermal runaway ,Renewable Energy, Sustainability and the Environment ,Transition temperature ,Energy Engineering and Power Technology ,Nanotechnology ,02 engineering and technology ,Polymer ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Thermal expansion ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Fuel Technology ,chemistry ,Electrical resistivity and conductivity ,Electrode ,Composite material ,0210 nano-technology ,Overheating (electricity) - Abstract
Safety issues have been a long-standing obstacle impeding large-scale adoption of next-generation high-energy-density batteries. Materials solutions to battery safety management are limited by slow response and small operating voltage windows. Here we report a fast and reversible thermoresponsive polymer switching material that can be incorporated inside batteries to prevent thermal runaway. This material consists of electrochemically stable graphene-coated spiky nickel nanoparticles mixed in a polymer matrix with a high thermal expansion coefficient. The as-fabricated polymer composite films show high electrical conductivity of up to 50 S cm−1 at room temperature. Importantly, the conductivity decreases within one second by seven to eight orders of magnitude on reaching the transition temperature and spontaneously recovers at room temperature. Batteries with this self-regulating material built in the electrode can rapidly shut down under abnormal conditions such as overheating and shorting, and are able to resume their normal function without performance compromise or detrimental thermal runaway. Our approach offers 103–104 times higher sensitivity to temperature changes than previous switching devices. Safety is a major issue in the development of lithium-ion batteries. Now, a thermoresponsive polymer composite embedded into electrodes is shown to rapidly shut down batteries at overheating but quickly resume function at normal conditions.
- Published
- 2016
48. A Comparative Study of Soldering Temperatures and Materials on the Reliability of Photovoltaic Modules
- Author
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Po Chun Hsu, Yang Hsien Lee, Chin Yang Huang, Zhu Fu Hsieh, Keh-Moh Lin, and Wen Yeong Huang
- Subjects
Silver paste ,Reliability (semiconductor) ,Materials science ,Dip soldering ,law ,Soldering ,Metallurgy ,Photovoltaic system ,Solar cell ,General Engineering ,Composite material ,Soldering process ,law.invention - Abstract
To find out the important factors which decisively affect the soldering quality of photovoltaic modules, solar cells were soldered under different conditions (different temperatures, PbSn vs. SnAgCu solder, manual vs. semi-automatic). Experimental results show that the soldering quality of PbSn under 350°C in the semi-automatic soldering process was quite stable while the soldering quality of lead-free solder was generally unacceptable in the manual or semi-automatic process under different temperatures. This result indicates that the soldering process with lead-free solder still needs to be further improved. It was also found that most cracks were formed on the interface between the solder and the silver paste and then expanded outwards.
- Published
- 2012
49. Efficient solar-driven water splitting by nanocone BiVO4-perovskite tandem cells
- Author
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Yongcai Qiu, Wei Liu, Wei Chen, Guangmin Zhou, Po-Chun Hsu, Rufan Zhang, Zheng Liang, Shoushan Fan, Yuegang Zhang, and Yi Cui
- Subjects
Materials science ,Perovskite solar cell ,Nanotechnology ,02 engineering and technology ,nanocone array ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Nanopores ,Porous BiVO4 ,Solar Energy ,Electrodes ,Research Articles ,Perovskite (structure) ,Photocurrent ,Titanium ,Multidisciplinary ,integumentary system ,business.industry ,Nanoporous ,photoelectrochemical water splitting ,Energy conversion efficiency ,food and beverages ,Water ,SciAdv r-articles ,Oxides ,Materials Engineering ,Calcium Compounds ,021001 nanoscience & nanotechnology ,Silicon Dioxide ,perovskite solar cell ,0104 chemical sciences ,chemistry ,Bismuth vanadate ,biological sciences ,Water splitting ,Optoelectronics ,Reversible hydrogen electrode ,Nanoparticles ,light trapping ,Vanadates ,0210 nano-technology ,business ,Bismuth ,Research Article - Abstract
Efficient solar water splitting is achieved by a nanocone BiVO4 photoelectrochemical cell in tandem with a perovskite solar cell., Bismuth vanadate (BiVO4) has been widely regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting because of its low cost, its high stability against photocorrosion, and its relatively narrow band gap of 2.4 eV. However, the achieved performance of the BiVO4 photoanode remains unsatisfactory to date because its short carrier diffusion length restricts the total thickness of the BiVO4 film required for sufficient light absorption. We addressed the issue by deposition of nanoporous Mo-doped BiVO4 (Mo:BiVO4) on an engineered cone-shaped nanostructure, in which the Mo:BiVO4 layer with a larger effective thickness maintains highly efficient charge separation and high light absorption capability, which can be further enhanced by multiple light scattering in the nanocone structure. As a result, the nanocone/Mo:BiVO4/Fe(Ni)OOH photoanode exhibits a high water-splitting photocurrent of 5.82 ± 0.36 mA cm−2 at 1.23 V versus the reversible hydrogen electrode under 1-sun illumination. We also demonstrate that the PEC cell in tandem with a single perovskite solar cell exhibits unassisted water splitting with a solar-to-hydrogen conversion efficiency of up to 6.2%.
- Published
- 2015
50. Pulsed laser deposition of (MoO3)1−x(V2O5)x thin films: Preparation, characterization and gasochromic studies
- Author
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Jiu Yong Luo, Po-Chun Hsu, Wei Hsiang Chao, Chia-Hao Hsu, Tzu Wen Huang, Kuo Wei Yeh, Chung-Chieh Chang, Chung-Ting Ke, Mau Kuen Wu, Ta Kun Chen, and Ming-Jye Wang
- Subjects
Materials science ,Composite oxide ,Hydrogen ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Pulsed laser deposition ,Catalysis ,Characterization (materials science) ,chemistry ,Materials Chemistry ,Thin film ,Platinum - Abstract
In this study we demonstrate a new composite oxide thin films of (MoO 3 ) 1 − x (V 2 O 5 ) x , x = 0, 0.01, 0.03, and 0.05, fabricated by pulsed laser deposition (PLD). The performance of platinum (Pt) catalyst activated hydrogen gas sensor with modified (MoO 3 ) 1 − x (V 2 O 5 ) x thin films were investigated. The thickness of the (MoO 3 ) 1 − x (V 2 O 5 ) x thin film is about 600–650 nm and its surface has a uniform morphology. Our results show that the gasochromic sensors prepared by (MoO 3 ) 0.99 (V 2 O 5 ) 0.01 thin film exhibited excellent hydrogen sensibility. The response and recovery time are in the range of 9–15 min for coloration and bleaching at room temperature under H 2 atmosphere. The results also show that (MoO 3 ) 1 − x (V 2 O 5 ) x /Pt (x = 0.01, 0.03, 0.05) thin films perform better gasochromic capability than the pristine MoO 3 /Pt sample.
- Published
- 2010
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