94 results on '"Wei-Fang Su"'
Search Results
2. Validated Analysis of Component Distribution Inside Perovskite Solar Cells and Its Utility in Unveiling Factors of Device Performance and Degradation
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Li-Ji Jhang, Jing-Jong Shyue, Wei-Fang Su, Feng-Yu Tsai, Jay Shieh, Cheng-Hung Hou, Shu-Han Hung, Pi-Tai Chou, Keh-Jiunh Chou, and Yu-Kai Hu
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Materials science ,Ion beam ,business.industry ,Perovskite solar cell ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Mass spectrometry ,01 natural sciences ,0104 chemical sciences ,Physics::Plasma Physics ,Component (UML) ,Optoelectronics ,Degradation (geology) ,General Materials Science ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) has been used for gaining insights into perovskite solar cells (PSCs). However, the importance of selecting ion beam parameters to eliminate artifacts in the resulting depth profile is often overlooked. In this work, significant artifacts were identified with commonly applied sputter sources, i.e., an O
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- 2020
3. Low-Temperature Processed Tin Oxide Transistor With Ultraviolet Irradiation
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Chun Fu Lu, Wei-Fang Su, Cheng Wei Shih, Albert Chin, and Te Jui Yen
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010302 applied physics ,Materials science ,Subthreshold conduction ,business.industry ,Transistor ,Tin oxide ,medicine.disease_cause ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,X-ray photoelectron spectroscopy ,law ,Thin-film transistor ,Logic gate ,0103 physical sciences ,medicine ,Optoelectronics ,Irradiation ,Electrical and Electronic Engineering ,business ,Ultraviolet - Abstract
Using a novel ultraviolet (UV) irradiation method, we processed a high-performance thin-film transistor (TFT) at low temperatures. Satisfactory device integrity that was demonstrated by high field-effect mobility values of 92 and 43 cm2/Vs, small subthreshold slopes of 74 and 81 mV/decade, and ON-current/ OFF-current values of $3\times 10^{6}$ and $7\times 10^{5}$ was achieved for the SnO2 TFT at low processing temperatures of 180 °C and 100 °C, respectively. The results of X-ray photoelectron spectroscopy showed that the UV irradiation considerably increased the presence of Sn4+ and reduced the presence of unwanted Sn2+, even at low processing temperatures, improving the quality of SnO2.
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- 2019
4. High face-on ratio isoindigo copolymers with extended nano-fibrillar networks in fullerene-based thick (>300 nm) photovoltaics achieving a high efficiency of 10.7%
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Chin-Ti Chen, Chun-Fu Lu, Adane Desta Fenta, Song-Fu Liao, Chi-Yang Chao, and Wei-Fang Su
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chemistry.chemical_classification ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,Heterojunction ,02 engineering and technology ,General Chemistry ,Electron acceptor ,021001 nanoscience & nanotechnology ,Polymer solar cell ,Crystallinity ,Chemical engineering ,chemistry ,Photovoltaics ,Nano ,General Materials Science ,0210 nano-technology ,business ,HOMO/LUMO - Abstract
Three D–A π-conjugated copolymers PnTIF (where n = 2, 4, or 6), composed of isoindigo electron acceptor units and difluorinated bithiophene (BTF) electron donor units, were synthesized and characterized. The HOMO and LUMO energy levels, solubility (and miscibility with PCBM), crystallinity (and crystalline orientation) and PnTIF:PCBM thin film morphology (nano-fibrillar network and phase separation) of the copolymers could be adjusted by the number (0 for P2TIF, 1 for P4TIF, 2 for P6TIF) of flexible 3-dodecylthiophene spacers between the isoindigo and BTF units. From the tested polymer solar cells fabricated with PnTIF:PCBM bulk heterojunctions, P4TIF:PC61BM solar cells exhibited a remarkably high short-circuit current density of ∼22 mA cm−2 together with a fill factor of ∼61% and an open-circuit voltage >0.80 volt, resulting in a power conversion efficiency of 10.7%, making it one of the highest among PC61BM-based polymer solar cells.
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- 2019
5. Enhancing the efficiency of perovskite solar cells using mesoscopic zinc-doped TiO2 as the electron extraction layer through band alignment
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Shun-Hsiang Chan, Shih-Hsuan Chen, Meng-Huan Jao, Wei-Fang Su, Ming-Chung Wu, Yang-Fang Chen, and Kun Mu Lee
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Kelvin probe force microscope ,Electron mobility ,Materials science ,Absorption spectroscopy ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Optoelectronics ,General Materials Science ,Charge carrier ,0210 nano-technology ,business ,Ultraviolet photoelectron spectroscopy ,Perovskite (structure) - Abstract
Lead halide perovskite-structured solar cells (PSCs) have drawn great attention due to a rapid improvement in their photoelectric conversion efficiency in recent years. In this study, we have enhanced photovoltaic performance by using mesoscopic zinc-doped TiO2 (meso-Zn:TiO2) as the electron extraction layer. Zn:TiO2 nanoparticles (Zn:TiO2 NPs) with various zinc doping levels were synthesized by combining sol–gel and hydrothermal methods. The synthesized Zn:TiO2 NPs were used to fabricate electron extraction layers by a screen-printing method. We systematically investigated the surface morphology, crystal structure, contact angle, charge carrier dynamics, electron mobility, and electrical conductivity of various meso-Zn:TiO2. Furthermore, photo-assisted Kelvin probe force microscopy (KPFM) was used to analyze the surface potential of perovskite films coated with various meso-Zn:TiO2 to understand the electron extraction behavior under the illumination of light at various wavelengths. Moreover, the energy levels of various meso-Zn:TiO2 were estimated by ultraviolet photoelectron spectroscopy (UPS) and UV-vis absorption spectroscopy. We discovered that the 5.0 mol% meso-Zn:TiO2 exhibited the optimal band alignment with perovskite. Finally, the average power conversion efficiency (PCE) of PSCs with meso-Zn:TiO2 was enhanced from 13.1 to 16.8%, and such fabricated PSC yielded a champion PCE of 18.3%.
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- 2018
6. Improved efficiency of perovskite photovoltaics based on Ca-doped methylammonium lead halide
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Tzu-Hao Lin, Wei-Fang Su, Shun-Hsiang Chan, and Ming-Chung Wu
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Materials science ,Dopant ,business.industry ,General Chemical Engineering ,Doping ,Inorganic chemistry ,Energy conversion efficiency ,Halide ,Perovskite solar cell ,02 engineering and technology ,General Chemistry ,Methylammonium lead halide ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Photovoltaics ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Hybrid lead halide perovskite structured materials have created enormous expectations for low-cost and high-performance optoelectronic devices. The light-harvesting active layer of perovskite solar cell consists of hybrid organic-inorganic lead halide-based material. In this study, we successfully fabricated the perovskite photovoltaics with partial substitution of the lead cation (Pb 2+ ) with calcium ion (Ca 2+ ). The incorporation of Ca 2+ into the original structure was analyzed to observe the doping effect on the crystalline structure and the optical properties. Moreover, UV–vis spectra showed the decreased bandgap with ascending the dopants Ca 2+ amount. 1.0 mol% Ca-doped perovskite film has the lower emission energy, and it shows the low recombination behavior. After optimizing the perovskite solar cells, the V oc is increased from 0.93 to 0.98 V, the J sc is increased from 17.4 to 19.1 mA/cm 2 and the power conversion efficiency is enhanced from 10.7 to 12.9% by using 1.0 mol% Ca-doped perovskite material.
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- 2017
7. Chloride gradient render carrier extraction of hole transport layer for high V and efficient inverted organometal halide perovskite solar cell
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Meng-Huan Jao, Jing-Jong Shyue, Wei-Fang Su, Kai-Chi Hsiao, Ming-Chung Wu, Cheng-Hung Hou, Ting-Han Lin, and Bo-Ting Lee
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Materials science ,Passivation ,Band gap ,business.industry ,General Chemical Engineering ,Photovoltaic system ,Halide ,Perovskite solar cell ,Hole transport layer ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Chloride ,Industrial and Manufacturing Engineering ,0104 chemical sciences ,Transport layer ,medicine ,Environmental Chemistry ,Optoelectronics ,0210 nano-technology ,business ,medicine.drug - Abstract
A carrier transport layer and its interfacial effects on an organometal halide perovskite light harvesting layer play an influential factor in either photovoltaic performance or long-term stability of a perovskite solar cell (OHPSC). Although the understandings of the carrier transport layers and interfacial effects on regular structured OHPSCs have been explored, knowledge of an interface between hole transport layer of NiOx and perovskite in an inverted OHPSC is still necessary to be developed. Here, we performed a universal NiOx film with the sequential passivation strategy of NiCl2 (SPS-NiCl2 treatment) for either wide bandgap or narrow bandgap of OHPSCs. The SPS-NiCl2 treated NiOx film not only implements the passivation at the perovskite layer/NiOx film interface but also confers itself a gradient energy level of valance band inducing by chloride. Comprehensive characterizations reveal that the SPS-NiCl2 treated NiOx film suppresses non-radiative recombination at the interface and enlarges the splitting of the quasi-Fermi level at the interfaces. The photoconversion efficiency (PCE) of the champion device comprised of the SPS-NiCl2 treated NiOx film can achieve 19.53% with a record Voc of 1.16 V, the lowest Voc deficit of 390 mV in NiOx based inverted OHPSCs. The corresponding devices with encapsulation also exhibit superior long-term stability, and over 80% of initial PCE can be maintained after 1500 h damp-heat test. This study sheds the light on managing the interfacial issues of an inverted OHPSC and offers a feasible path to develop a universal hole transport layer for perovskite layers with different energy bandgap.
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- 2021
8. Enhancing perovskite solar cell performance and stability by doping barium in methylammonium lead halide
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Wei-Cheng Chen, Kun-Mu Lee, Tzu-Hao Lin, Wei-Fang Su, Ming-Chung Wu, and Shun-Hsiang Chan
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Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,Inorganic chemistry ,Energy conversion efficiency ,Perovskite solar cell ,Halide ,02 engineering and technology ,General Chemistry ,Methylammonium lead halide ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Photovoltaics ,Solar cell ,General Materials Science ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Organic–inorganic lead halide perovskite solar cells are considered as one of the most promising technologies for future photovoltaics because they show high power conversion efficiency (PCE) and can be fabricated through a simple solution process. Non-toxic alkaline-earth metal cations are suitable candidates to replace toxic lead in perovskite because they maintain the charge balance in perovskite and some of them meet the tolerance factor of Goldschmidt's rule. We investigated four kinds of alkaline-earth metal cations (Mg2+, Ca2+, Sr2+, and Ba2+) to replace lead cations partially. Among these four alkaline-earth metals, the Ba2+ is most suitable for Pb2+ replacement in perovskite films and exhibits the best power conversion efficiency. Furthermore, we systematically studied the crystal structure, absorption behavior and surface morphology of Ba2+-doped perovskite films with different doping levels. The relationship between the charge carrier dynamics and Ba2+ concentration was evaluated by the time-resolved photoluminescence (TRPL) technique. The Ba2+-doped perovskite films that can be processed in the environment containing moisture (1.0% relative humidity) are stable. At the optimal 3.0 mol% Ba2+ replacement, the PCE of the fabricated solar cell is increased from 11.8 to 14.0%, and the PCE of champion devices is as high as 14.9% with increased storage stability.
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- 2017
9. Perovskite Solar Cells: Toward All Slot‐Die Fabricated High Efficiency Large Area Perovskite Solar Cell Using Rapid Near Infrared Heating in Ambient Air (Adv. Energy Mater. 37/2020)
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Shih-Han Huang, Chia-Feng Li, Wei-Fang Su, Pei-Huan Lee, Cheng‐Kang Guan, Hung‐Che Huang, and Yu-Ching Huang
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Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Near-infrared spectroscopy ,Optoelectronics ,Perovskite solar cell ,General Materials Science ,business ,Near infrared radiation ,Energy (signal processing) ,Die (integrated circuit) ,Ambient air ,Perovskite (structure) - Published
- 2020
10. Extraordinarily Sensitive and Low-Voltage Operational Cloth-Based Electronic Skin for Wearable Sensing and Multifunctional Integration Uses: A Tactile-Induced Insulating-to-Conducting Transition
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Chun-Fu Lu, Wei-Fang Su, Meng-Huan Jao, Wen-Yi Hung, Chien-Tung Chen, Yang-Fang Chen, Bo-Wei Ye, Tai-Yuan Lin, and Ying-Chih Lai
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Resistive touchscreen ,Materials science ,Wearable sensing ,business.industry ,Electronic skin ,Nanotechnology ,Robotics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Pressure sensor ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Electrochemistry ,Artificial intelligence ,0210 nano-technology ,business ,Low voltage ,Wearable technology ,Voltage - Abstract
Electronic skin sensing devices are an emerging technology and have substantial demand in vast practical fields including wearable sensing, robotics, and user-interactive interfaces. In order to imitate or even outperform the capabilities of natural skin, the keen exploration of materials, device structures, and new functions is desired. However, the very high resistance and the inadequate current switching and sensitivity of reported electronic skins hinder to further develop and explore the promising uses of the emerging sensing devices. Here, a novel resistive cloth-based skin-like sensor device is reported that possesses unprecedented features including ultrahigh current-switching behavior of ≈107 and giant high sensitivity of 1.04 × 104–6.57 × 106 kPa−1 in a low-pressure region of
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- 2016
11. Achieving a high fill factor for organic solar cells
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Wei-Fang Su, Meng-Huan Jao, and Hsueh-Chung Liao
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Organic solar cell ,Equivalent series resistance ,Renewable Energy, Sustainability and the Environment ,Open-circuit voltage ,business.industry ,Energy conversion efficiency ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Material Design ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,Renewable energy ,Equivalent circuit ,General Materials Science ,0210 nano-technology ,business ,Short circuit - Abstract
Organic photovoltaics (OPVs) have developed rapidly in the last decades due to their potential for providing cost-efficient, low-energy consumption, and environmentally friendly renewable energy sources. Some research reports have focused on the device physics of organic photovoltaics that governs open circuit voltage (Voc) and short circuit current (Jsc) to improve their performance. In this review, we focus on the third parameter, fill factor (FF), that is equally important in determining the power conversion efficiency. We discuss the mathematical calculation of the FF and the relationship between the FF and equivalent circuit model elements, namely, shunt resistance, series resistance, and diode ideal factor. In order to provide a strategy toward a high FF for OPVs from the viewpoints of device design and material synthesis, we review important device features and BHJ features that have a large impact on the device FF, including preventing shorting, buffer layer design, domain size or purity, gradated BHJ structures, π–π stacking distance or direction, etc. We hope this article can provide a comprehensive insight into elements controlling the FF of OPVs and give a valuable direction for better device and material design.
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- 2016
12. Achieving High‐Performance Perovskite Photovoltaic by Morphology Engineering of Low‐Temperature Processed Zn‐Doped TiO 2 Electron Transport Layer
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Wei-Fang Su, Kun-Mu Lee, Ming-Chung Wu, Shih-Hsuan Chen, Yen-Tung Lin, Chao-Sung Lai, Yang-Fang Chen, Meng-Huan Jao, and Yin-Hsuan Chang
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Materials science ,business.industry ,Photovoltaic system ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Space charge ,0104 chemical sciences ,Biomaterials ,Contact angle ,Crystallinity ,Deposition (phase transition) ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Layer (electronics) ,Biotechnology ,Perovskite (structure) - Abstract
Perovskite solar cells (PSCs) have become one of the most promising renewable energy converting devices. However, in order to reach a sufficiently high power conversion efficiency (PCE), the PSCs typically require a high-temperature sintering process to prepare mesostructured TiO2 as an efficient electron transport layer (ETL), which prohibits the PSCs from commercialization in the future. This work investigates a low-temperature synthesis of TiO2 nanocrystals and introduces a two-fluid spray coating process to produce a nanostructured ETL for the following deposition of perovskite layer. The temperature during the whole deposition process can be maintained under 150 °C. Compared to the typical planar TiO2 layer, the perovskite layer fabricated on a nanostructured TiO2 layer shows uniform compactness, preferred orientation, and high crystallinity, leading to reproducible and promising device performance. The detail mechanisms are revealed by the contact angle test, morphology characterization, grazing incident wide angle X-Ray scattering measurement, and space charge limited currents analysis. Finally, optimized device performance can be achieved through adequate Zn doping in the TiO2 layer, demonstrating an average PCE of 19.87% with champion PCE of 21.36%. The efficiency can maintain over 80% of its original value after 3000 h storage in ambient atmosphere. This study suggests a promising approach to offer high-efficiency PSCs using the low-temperature process.
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- 2020
13. High-efficiency perovskite solar cell using cobalt doped nickel oxide hole transport layer fabricated by NIR process
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Pei-Huan Lee, Wei-Fang Su, Bo-Ting Li, Yu-Ching Huang, Chia-Feng Lee, and Zhi-Hao Huang
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Electron mobility ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Nickel oxide ,Energy conversion efficiency ,Doping ,Perovskite solar cell ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Optoelectronics ,Work function ,0210 nano-technology ,business ,Deposition (law) ,Perovskite (structure) - Abstract
Lead halide perovskite solar cells (PVSCs) have potential toward commercialization because of their high efficiency and low cost. The hole transport layer (HTL) of p-i-n perovskite solar cell is usually made of NiOX. However, the NiOX needs to be processed at 300 °C for 15 min for good hole transport property. This long heating time prohibits the development of continuous commercial process. Thus, a rapid heating process for the NiOX film deposition is critical to realize the commercialization of PVSCs in the future. In this study, we develop a facile method to obtain high quality NiOX films annealed by NIR in a short time of 50 s. A short-wave NIR lamp at 2500 K was used to systematically investigate the effect of NIR intensity on the film quality of sol-gel NiOX. The PVSCs fabricated from NIR-annealed NiOX (NIR-NiOX) film show a comparable power conversion efficiency (PCE) to those fabricated from traditional hot-plate annealed-NiOX (HP-NiOX). In addition, the NIR annealed cobalt-doped NiOX (NIR-Co:NiOX) was synthesized to replace pristine NIR-NiOX. The PCE of PVSCs fabricated from this new NiOX film can be increased from 15.99% to 17.77%, which is due to the efficient hole extraction, less charge accumulation, and reducing Voc loss resulting from the improved hole mobility, reduced interface resistance and well-matched work function. Our study paves a way to fulfill the requirements of low cost and low energy consumption of large scale production of high efficiency PVSCs.
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- 2020
14. Liquid crystalline epoxy nanocomposite material for dental application
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Rung-Shu Chen, Min-Huey Chen, Yun-Yuan Tai, Sheng-Hao Hsu, and Wei-Fang Su
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Dental Stress Analysis ,Filler (packaging) ,Friction ,Biocompatibility ,Orthodontic Brackets ,Core (manufacturing) ,Indentation hardness ,Nanocomposites ,biocompatibility ,liquid crystalline epoxy nanocomposite ,Materials Testing ,Medicine ,Composite material ,Shrinkage ,Medicine(all) ,lcsh:R5-920 ,Nanocomposite ,Epoxy Resins ,business.industry ,Bracket ,General Medicine ,Epoxy ,visual_art ,microhardness ,visual_art.visual_art_medium ,frictional force of dental brackets ,Stress, Mechanical ,lcsh:Medicine (General) ,business - Abstract
Background/Purpose Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. Methods In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. Results The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. Conclusion The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment.
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- 2015
15. Hierarchical i–p and i–n porous heterojunction in planar perovskite solar cells
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Meng-Huan Jao, Che-Pu Hsu, Jing-Jong Shyue, Hsueh-Chung Liao, Wei-Fang Su, Charn-Yin Chen, Yu-Ching Huang, Chun-Jen Su, Cheng-Si Tsao, and Kuo-Yo Tian
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Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Scattering ,Nanotechnology ,Heterojunction ,General Chemistry ,law.invention ,Secondary ion mass spectrometry ,law ,Solar cell ,Optoelectronics ,Grazing-incidence small-angle scattering ,General Materials Science ,business ,Porosity ,Nanoscopic scale ,Perovskite (structure) - Abstract
A hierarchical pore network in planar CH3NH3PbI3 perovskite is demonstrated herein. Quantitative characterizations by grazing incidence small angle X-ray scattering (GISAXS) with modeling and complementary microscopic observations provide insight at various length scales. It is a pore structure comprised of nano-scaled primary pores aggregating into meso-scaled fractal networks within the perovskite layer. Its structural evolution and mechanistic interpretation are explored with respect to different preparation methods/steps. The time-of-flight secondary ion mass spectrometer (TOF-SIMS) results suggest the infiltration of hole transporting materials (HTM) or electron transporting materials (ETM) deposited on top at different length scales. The inter-penetrating perovskite/HTM or perovskite/ETM form i–p or i–n one-sided porous heterojunctions, respectively, over the typically regarded planar-stacked heterojunction. They show distinctive photovoltaic characteristics and behaviors in which the large i–n interfaces at the nanoscale lead to highly efficient, hysteresis-free and reliable solar cell devices. The morphology–performance correlation is helpful for associated design of device architecture and processing toward higher efficiency and stability.
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- 2015
16. Morphological Control Agent in Ternary Blend Bulk Heterojunction Solar Cells
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Wei-Fang Su, Hsueh-Chung Liao, Po Hsuen Chen, and Robert P. H. Chang
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chemistry.chemical_classification ,additive ,Materials science ,Polymers and Plastics ,Organic solar cell ,business.industry ,Photovoltaic system ,ternary blend system ,bulk heterojunction ,Nanotechnology ,General Chemistry ,Compatibilization ,Polymer ,Solar energy ,Polymer solar cell ,lcsh:QD241-441 ,chemistry.chemical_compound ,lcsh:Organic chemistry ,chemistry ,morphology ,organic solar cell ,Ternary operation ,business ,Inorganic nanoparticles - Abstract
Bulk heterojunction (BHJ) organic photovoltaic (OPV) promise low cost solar energy and have caused an explosive increase in investigations during the last decade. Control over the 3D morphology of BHJ blend films in various length scales is one of the pillars accounting for the significant advance of OPV performance recently. In this contribution, we focus on the strategy of incorporating an additive into BHJ blend films as a morphological control agent, i.e., ternary blend system. This strategy has shown to be effective in tailoring the morphology of BHJ through different inter- and intra-molecular interactions. We systematically review the morphological observations and associated mechanisms with respect to various kinds of additives, i.e., polymers, small molecules and inorganic nanoparticles. We organize the effects of morphological control (compatibilization, stabilization, etc.) and provide general guidelines for rational molecular design for additives toward high efficiency and high stability organic solar cells.
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- 2014
17. Remarkably High Hole Mobility Metal-Oxide Thin-Film Transistors
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Albert Chin, Chun Fu Lu, Cheng Wei Shih, and Wei-Fang Su
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Electron mobility ,Materials science ,Oxide ,chemistry.chemical_element ,lcsh:Medicine ,02 engineering and technology ,01 natural sciences ,Article ,law.invention ,chemistry.chemical_compound ,Effective mass (solid-state physics) ,Sputtering ,law ,0103 physical sciences ,lcsh:Science ,010302 applied physics ,Multidisciplinary ,business.industry ,Transistor ,lcsh:R ,021001 nanoscience & nanotechnology ,Subthreshold slope ,chemistry ,Thin-film transistor ,Optoelectronics ,lcsh:Q ,0210 nano-technology ,business ,Tin - Abstract
High performance p-type thin-film transistor (p-TFT) was realized by a simple process of reactive sputtering from a tin (Sn) target under oxygen ambient, where remarkably high field-effect mobility (μ FE ) of 7.6 cm2/Vs, 140 mV/dec subthreshold slope, and 3 × 104 on-current/off-current were measured. In sharp contrast, the SnO formed by direct sputtering from a SnO target showed much degraded μ FE , because of the limited low process temperature of SnO and sputtering damage. From the first principle quantum-mechanical calculation, the high hole μ FE of SnO p-TFT is due to its considerably unique merit of the small effective mass and single hole band without the heavy hole band. The high performance p-TFTs are the enabling technology for future ultra-low-power complementary-logic circuits on display and three-dimensional brain-mimicking integrated circuits.
- Published
- 2017
18. Plasmonic nanoparticle-film calipers for rapid and ultrasensitive dimensional and refractometric detection
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Wei-Fang Su, Keng-Te Lin, Hsuen-Li Chen, Yi-Chuan Tseng, Sin-Yi Chou, Chang-Ching Shao, and Chen-Chieh Yu
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Materials science ,Nanoparticle ,Nanotechnology ,Biosensing Techniques ,Biochemistry ,Chemistry Techniques, Analytical ,Analytical Chemistry ,Electrochemistry ,Environmental Chemistry ,Cysteine ,Angstrom ,Anisotropy ,Homocysteine ,Spectroscopy ,Plasmon ,business.industry ,Resolution (electron density) ,Discriminant Analysis ,Glutathione ,Refractometry ,Wavelength ,Nanoparticles ,Optoelectronics ,Calipers ,business ,Refractive index - Abstract
In this study, we develop an ultrasensitive nanoparticle (NP)-film caliper that functions with high resolution (angstrom scale) in response to both the dimensions and refractive index of the spacer sandwiched between the NPs and the film. The anisotropy of the plasmonic gap mode in the NP-film caliper can be characterized readily using spectroscopic ellipsometry (SE) without the need for further optical modeling. To the best of our knowledge, this paper is the first to report the use of SE to study the plasmonic gap modes in NP-film calipers and to demonstrate that SE is a robust and convenient method for analyzing NP-film calipers. The high sensitivity of this system originates from the plasmonic gap mode in the NP-film caliper, induced by electromagnetic coupling between the NPs and the film. The refractometric sensitivity of this NP-film caliper reaches up to 314 nm per RIU, which is superior to those of other NP-based sensors. The NP-film caliper also provides high dimensional resolution, down to the angstrom scale. In this study, the shift in wavelength in response to the change in gap spacing is approximately 9 nm Å(-1). Taking advantage of the ultrasensitivity of this NP-film caliper, we develop a platform for discriminating among thiol-containing amino acids.
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- 2014
19. Additives for morphology control in high-efficiency organic solar cells
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Hsueh-Chung Liao, Chun-Chih Ho, Chih Yu Chang, Seth B. Darling, Meng Huan Jao, and Wei-Fang Su
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Materials science ,Organic solar cell ,business.industry ,Mechanical Engineering ,Energy conversion efficiency ,Nanotechnology ,Condensed Matter Physics ,Environmentally friendly ,Polymer solar cell ,Material selection ,Materials Science(all) ,Photovoltaics ,Mechanics of Materials ,Compatibility (mechanics) ,Energy transformation ,General Materials Science ,business - Abstract
Bulk heterojunction (BHJ) photovoltaics represent one of the most promising technologies in low-cost, high-throughput, environmentally friendly energy conversion. Morphological control is one pillar of the recent remarkable progress in power conversion efficiency. This review focuses on morphological control by processing with solvent additives, which has been extensively adopted and exhibits promising compatibility with large-scale processing. Recent investigations including material selection, morphological variations at various length scales, and interpretations of the interaction among additives and BHJ materials will be discussed. Insights into the role of solvent additives represent an important resource for further improvement in materials and processing designs.
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- 2013
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20. High mobility SnO2 TFT for display and future IC
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Wei-Fang Su, Chun Fu Lu, Albert Chin, and Cheng Wei Shih
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010302 applied physics ,Materials science ,business.industry ,Orders of magnitude (temperature) ,Transistor ,High resolution ,Nanotechnology ,02 engineering and technology ,Integrated circuit ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,law ,Thin-film transistor ,0103 physical sciences ,MOSFET ,Optoelectronics ,0210 nano-technology ,business - Abstract
Very high mobility of 149∼189 cm2/Vs, large on-to-off current ratio (I ON /I Off ) of >7 orders of magnitude, fast turn-on sub-threshold swing of 110 mV/decade, and low power operation at 2∼2.5 V were achieved in SnO 2 TFT device at an ultra-thin SnO 2 thickness of 4.5 nm. The device mobility of SnO 2 TFT is higher than the best ZnO-based TFTs and CVD-grown multi-layers MoS 2 MOSFETs. The reached mobility is already 0.7 times of universal mobility of SiO 2 /Si nMOSFET, operated typically at >1 MV/cm field. The very high mobility, simple low temperature process, and ultra-thin body SnO 2 transistor should find its crucial role for high resolution display, future sub-10 nm nMOSFET and brain-mimicking 3D IC.
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- 2016
21. Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals
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Chen Wei Shih, Chun Fu Lu, Wei-Fang Su, and Albert Chin
- Subjects
Computer science ,Induced high electron mobility transistor ,Oxide ,02 engineering and technology ,Integrated circuit ,computer.software_genre ,01 natural sciences ,Article ,law.invention ,Ion ,chemistry.chemical_compound ,law ,0103 physical sciences ,Thin film ,010302 applied physics ,Multidisciplinary ,business.industry ,Transistor ,021001 nanoscience & nanotechnology ,chemistry ,Thin-film transistor ,Optoelectronics ,Data mining ,0210 nano-technology ,business ,computer - Abstract
High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals.
- Published
- 2016
22. Enhancing P3HT/TiO2 Hybrid Photovoltaic Performance by Incorporating High Surface Potential Silica Nanodots into Hole Transport Layer
- Author
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Wei-Ben Wang, Wei-Fang Su, Jhih-Fong Lin, Chun-Chih Ho, Jwo-Huei Jou, and Yang-Fang Chen
- Subjects
Conductive polymer ,Materials science ,business.industry ,Photovoltaic system ,Energy conversion efficiency ,Hole transport layer ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,chemistry ,PEDOT:PSS ,Optoelectronics ,Nanodot ,Physical and Theoretical Chemistry ,business ,Ionomer ,Short circuit - Abstract
We offer a novel approach to improve the performance of P3HT/TiO2 hybrid photovoltaic devices by incorporating either hydroxyl- or amino-functionalized silica nanodots (SND–OH or SND–NH2) into the hole transport layer of the PEDOT:PSS. The SNDs serve as screens between conducting polymer and ionomer PSS to improve the phase separation and charge transport of the PEDOT:PSS hole transport layer. The power conversion efficiency (PCE) was thus improved by 1.45 and 2.61 fold for devices fabricated with PEDOT:PSS containing 1 wt % of SND–OH (SND–OH device) and 1 wt % of SND–NH2 (SND–NH2 device), respectively, when compared with the devices fabricated by neat PEDOT:PSS. The increase in PCE arises from an increase in short circuit currents, which are affected by the phase separation of PEDOT:PSS with possessing incorporated SNDs. The low surface potential of hydroxyl-functionalized SNDs (SND–OH) is easily aggregated in the PEDOT:PSS solution and forms large-sized phase separation in the PEDOT:PSS film. The aggreg...
- Published
- 2012
23. Correlating Interface Heterostructure, Charge Recombination, and Device Efficiency of Poly(3-hexyl thiophene)/TiO2 Nanorod Solar Cell
- Author
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Wei-Fang Su, Leeyih Wang, Tsung-Wei Zeng, Yu-Chieh Tu, Chun-Chih Ho, and Guan-Yao Tu
- Subjects
Kelvin probe force microscope ,Materials science ,business.industry ,Heterojunction ,Surfaces and Interfaces ,Condensed Matter Physics ,Acceptor ,Polymer solar cell ,chemistry.chemical_compound ,chemistry ,Electrochemistry ,Thiophene ,Optoelectronics ,General Materials Science ,Charge carrier ,Nanorod ,Surface charge ,business ,Spectroscopy - Abstract
The charge recombination rate in poly(3-hexyl thiophene)/TiO(2) nanorod solar cells is demonstrated to correlate to the morphology of the bulk heterojunction (BHJ) and the interfacial properties between poly(3-hexyl thiophene) (P3HT) and TiO(2). The recombination resistance is obtained in P3HT/TiO(2) nanorod devices by impedance spectroscopy. Surface morphology and phase separation of the bulk heterojunction are characterized by atomic force microscopy (AFM). The surface charge of bulk heterojunction is investigated by Kelvin probe force microscopy (KPFM). Lower charge recombination rate and lifetime have been observed for the charge carriers in appropriate heterostructures of hybrid P3HT/TiO(2) nanorod processed via high boiling point solvent and made of high molecular weight P3HT. Additionally, through surface modification on TiO(2) nan,orod, decreased recombination rate and longer charge carrier lifetime are obtained owing to creation of a barrier between the donor phases (P3HT) and the acceptor phases (TiO(2)). The effect of the film morphology of hybrid and interfacial properties on charge carrier recombination finally leads to different outcome of photovoltaic I-V characteristics. The BHJ fabricated from dye-modified TiO(2) blended with P3HT exhibits 2.6 times increase in power conversion efficiency due to the decrease of recombination rate by almost 2 orders of magnitude as compared with the BHJ made with unmodified TiO(2). In addition, the interface heterostructure, charge lifetime, and device efficiency of P3HT/TiO(2) nanorod solar cells are correlated.
- Published
- 2011
24. Effects of Gold Film Morphology on Surface Plasmon Resonance Using Periodic P3HT:PMMA/Au Nanostructures on Silicon Substrate for Surface-Enhanced Raman Scattering
- Author
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Jia-Han Li, Yi Chou, Chun-Hway Hsueh, Shih-Wen Chen, Ming-Chung Wu, and Wei-Fang Su
- Subjects
Surface (mathematics) ,Materials science ,Morphology (linguistics) ,Nanostructure ,Silicon ,business.industry ,education ,technology, industry, and agriculture ,Analytical chemistry ,Physics::Optics ,chemistry.chemical_element ,Substrate (electronics) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,symbols.namesake ,General Energy ,chemistry ,Modulation ,symbols ,Optoelectronics ,Physical and Theoretical Chemistry ,Surface plasmon resonance ,business ,Raman scattering - Abstract
We study the effects of the morphology of gold film on the unusual modulation of surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) using the periodic nanostructures of P3...
- Published
- 2011
25. High-efficiency inverted polymer solar cells with solution-processed metal oxides
- Author
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Wen-Hao Wu, Guo-Dong Huang, Po-Ching Yang, Ching-Fuh Lin, Jing-Shun Huang, Wei-Fang Su, Ing-Jye Wang, Ming-Yi Lin, and Yu-Hong Lin
- Subjects
Photocurrent ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,food and beverages ,Polymer solar cell ,Cathode ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Active layer ,law.invention ,law ,Optoelectronics ,Nanorod ,Thin film ,business ,Layer (electronics) - Abstract
The selection of carrier transporting layer in polymer solar cells is an important issue because the nature and direction of carrier transport can be manipulated by inserting different functional layers in the device structure. In this work, we report a very efficient inverted polymer solar cell (PSC) system based on regioregular poly(3-hexylthiophene) and a n-type acceptor, bis-indene[C60]. With a pair of metal oxides and the insertion of TiO2 nanorods electron collecting layer between the ZnO thin film and the active layer, the device efficiency can be greatly improved. The contact area between the active layer and the electron collecting layer, as well as the thickness of active layer, can be increased with the incorporation of TiO2 nanorods. As a result, photocurrent can be enhanced due to more absorption of light and more charge separation interface. In addition, the larger contact area and the crystalline TiO2 nanorods provide a more efficient transporting route for the carriers to the cathode. The most efficient device demonstrated shows a high power conversion efficiency of 5.6% with the inverted structure.
- Published
- 2011
26. Exploiting optical anisotropy to increase the external quantum efficiency of flexible P3HT:PCBM blend solar cells at large incident angles
- Author
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Shang-Yu Chuang, Hsuen-Li Chen, Chun-Wei Chen, Wei-Fang Su, and Chen-Chieh Yu
- Subjects
Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Bent molecular geometry ,Substrate (electronics) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Nanoimprint lithography ,law.invention ,Optics ,law ,Electric field ,Reflection (physics) ,Optoelectronics ,Quantum efficiency ,business ,Refractive index - Abstract
The external quantum efficiencies of P3HT:PCBM blend solar cells decrease significantly when they are bent or illuminated at large incident angles because of (i) optical anisotropy of the P3HT:PCBM films—primarily because a mismatch between the direction of the electric field of the incoming light and the orientation of the P3HT:PCBM blend nanocrystallites results in a significant reduction in the amount of TM-polarized light absorbed and (ii) interfacial reflection of multilayer structures – primarily because the outermost air–flexible substrate interface exhibits a distinct refractive index difference – at large incident angles. Textured moth-eye structures fabricated by nanoimprint lithography on the flexible substrates of organic solar cells reduce the degree of interfacial reflection at high incident angles; they should allow more TE-polarized light to absorb in the P3HT:PCBM films (active layers) of the organic solar cells.
- Published
- 2011
27. Polymer/Metal Oxide Nanocrystals Hybrid Solar Cells
- Author
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Shao Sian Li, Wei-Fang Su, Chun-Wei Chen, and Yun-Yue Lin
- Subjects
Materials science ,business.industry ,Photovoltaic system ,Oxide ,food and beverages ,Nanotechnology ,Hybrid solar cell ,Quantum dot solar cell ,Atomic and Molecular Physics, and Optics ,Polymer solar cell ,law.invention ,chemistry.chemical_compound ,chemistry ,Photovoltaics ,law ,Solar cell ,Optoelectronics ,Nanorod ,Electrical and Electronic Engineering ,business - Abstract
In this paper, we present two different types of polymer/metal oxide nanocrystals hybrid photovoltaics. One is the poly(3-hexylthiophene) (P3HT)/TiO2 nanorods hybrid bulk heterojunction (BHJ) solar cell and the other is a nanostructured ZnO/P3HT hybrid solar cell. In a BHJ hybrid solar cell, the dispersed semiconducting nanocrystals lead to an increased interface area between polymer and nanocrystals, which can assist charge separation for photogenerated carriers, but at the expense of poorly formed conducting pathways for electron transport. In contrast, a nanostructured hybrid solar cell usually consists of rigidly connected nanocrystals, which can provide direct pathways for electron transport, but the interface area between polymer and nanocrystals is limited. We have demonstrated that through interface modification with effective molecules, the photovoltaic performance in both device structures can be largely improved by enhancing charge separation and suppressing interface recombination rate in the polymer/inorganic hybrids.
- Published
- 2010
28. Exploiting optical properties of P3HT:PCBM films for organic solar cells with semitransparent anode
- Author
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Wen-Jen Lee, Hsuen-Li Chen, S. Y. Chuang, Wei-Fang Su, and Chun-Hung Lin
- Subjects
Materials science ,Organic solar cell ,Absorption spectroscopy ,business.industry ,Annealing (metallurgy) ,Electric field amplitude ,Metals and Alloys ,Analytical chemistry ,Surfaces and Interfaces ,Optical thin film ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Active layer ,Anode ,Materials Chemistry ,Optoelectronics ,Thin film ,business - Abstract
In this study, we demonstrate optical properties of multilayer system in an organic solar cell based on poly (3-hexylthiophene) (P3HT) and 6,6-phenyl C61-butyric acid methyl ester (PCBM) with semitransparent anode through thermal annealing effect. The optical absorption is enhanced via optimizing annealing treatment which further elevates near-field electric field amplitude. The electric field amplitude at the interface (active layer/semitransparent anode) is enhanced after thermal annealing corresponding to effective absorption near to semitransparent anode. Moreover, the thickness of the active layer is optimized via optical thin-film model for enhancing the organic solar cell efficiency.
- Published
- 2010
29. Characteristics of n-type ZnO nanorods on top of p-type poly(3-hexylthiophene) heterojunction by solution-based growth
- Author
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Chun-Yu Lee, Wei-Fang Su, Sheng-Hao Hsu, Ching-Fuh Lin, and Jing-Shun Huang
- Subjects
Spin coating ,Materials science ,business.industry ,Metals and Alloys ,Nanotechnology ,Heterojunction ,Surfaces and Interfaces ,Electroluminescence ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Surface coating ,Materials Chemistry ,Hydrothermal synthesis ,Optoelectronics ,Nanorod ,business ,p–n junction ,Sol-gel - Abstract
We report that ZnO nanorods (NRs) are grown on an organic layer of poly(3-hexylthiophene) (P3HT) using a modified seeding layer. Thus, ZnO NRs/P3HT heterojunction light-emitting diodes could be fabricated using the hydrothermal method, in which ZnO acts as an n-type material and P3HT as a p-type material. The ZnO NRs improve the electron transportation in the devices. A three-fold enhancement of current density of the device is observed due to the NRs formed on the P3HT. The electroluminescence (EL) of the optimized ZnO-based device is 1.5 times larger than that without NRs. The influence of the P3HT thickness for the EL spectrum is also discussed.
- Published
- 2010
30. Manipulation of Nanoscale Phase Separation and Optical Properties of P3HT/PMMA Polymer Blends for Photoluminescent Electron Beam Resist
- Author
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Chun-Wei Chen, Che-Pu Hsu, Yi Chou, Wei-Che Yen, Yun-Yue Lin, Ming-Chung Wu, Wei-Fang Su, Yang-Fang Chen, Chih-Min Chuang, and Hsueh-Chung Liao
- Subjects
Potential well ,Materials science ,Photoluminescence ,business.industry ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Resist ,chemistry ,Polymer chemistry ,Materials Chemistry ,Optoelectronics ,Physical and Theoretical Chemistry ,Thin film ,Methyl methacrylate ,business ,Luminescence ,Absorption (electromagnetic radiation) ,Nanoscopic scale - Abstract
A novel photoluminescence electron beam resist made from the blend of poly(3-hexylthiophene) (P3HT) and poly(methyl methacrylate) (PMMA) has been successfully developed in this study. In order to optimize the resolution of the electron beam resist, the variations of nanophase separated morphology produced by differing blending ratios were examined carefully. Concave P3HT-rich island-like domains were observed in the thin film of the resist. The size of concave island-like domains decreased from 350 to 100 nm when decreasing the blending ratio of P3HT/PMMA from 1:5 to 1:50 or lower, concurrently accompanied by significant changes in optical properties and morphological behaviors. The lambda(max) of the film absorption is blue-shifted from 520 to 470 nm, and its lambda(max) of photoluminescence (PL) is also shifted from 660 to 550 nm. The radiative lifetime is shorter while the luminescence efficiency is higher when the P3HT/PMMA ratio decreases. These results are attributed to the quantum confinement effect of single P3HT chain isolated in PMMA matrix, which effectively suppresses the energy transfer between the well-separated polymer chains of P3HT. The factors affecting the resolution of the P3HT/PMMA electron beam resists were systematically investigated, including blending ratios and molecular weight. The photoluminescence resist with the best resolution was fabricated by using a molecular weight of 13 500 Da of P3HT and a blending ratio of 1:1000. Furthermore, high-resolution patterns can be obtained on both flat silicon wafers and rough substrates made from 20 nm Au nanoparticles self-assembled on APTMS (3-aminopropyltrimethoxysilane)-coated silicon wafers. Our newly developed electron beam resist provides a simple and convenient approach for the fabrication of nanoscale photoluminescent periodic arrays, which can underpin many optoelectronic applications awaiting future exploration.
- Published
- 2010
31. High-Sensitivity Raman Scattering Substrate Based on Au/La0.7Sr0.3MnO3 Periodic Arrays
- Author
-
Jhih-Fong Lin, Ming-Chung Wu, Che-Pu Hsu, Wei-Fang Su, Yi Chou, Yang-Fang Chen, and Chih-Min Chuang
- Subjects
Materials science ,business.industry ,Surface plasmon ,Substrate (electronics) ,Photoresist ,symbols.namesake ,Optics ,Resist ,symbols ,Cathode ray ,Optoelectronics ,General Materials Science ,Thin film ,business ,Raman scattering ,Electron-beam lithography - Abstract
We have developed Au/La(0.7)Sr(0.3)MnO(3) (Au/LSMO) periodic arrays with tunable surface plasmon properties that can be used as novel surface-enhanced Raman scattering (SERS) substrates. The periodic arrays are created by electron beam lithography of LSMO resist and metal film deposition. The LSMO electron beam resist is unique in that it exhibits either positive or negative resist behaviors depending on the electron beam dosage. Interestingly, surface plasmon behavior of the arrays can be controlled by just changing the electron beam dosage when presented with a fixed design pattern. Scanning confocal microscopy and spectral microreflectometry have been adapted to directly demonstrate this unique behavior. Furthermore, we show that our novel Au/LSMO array can be used as a high-sensitivity Raman scattering substrate. To illustrate this working principle, the Au/LSMO periodic array is applied to enhance the Raman scattering of a thin film containing 0.1 wt % poly-3-hexylthiophene (P3HT) in poly(methyl methacrylate) (PMMA). By controlling the geometry of the patterned substrate that exhibits gold surface plasmon near the excitation wavelength, we can enhance the intensity of Raman scattering of P3HT at 1350 cm(-1) up to 4 orders of magnitude as compared with previously generated planar Au substrates.
- Published
- 2009
32. Study of the effect of annealing process on the performance of P3HT/PCBM photovoltaic devices using scanning-probe microscopy
- Author
-
Shao Sian Li, Chun-Wei Chen, Ming-Chung Wu, Yu Chia Liao, Wei-Fang Su, and Yu-Ching Huang
- Subjects
Materials science ,Absorption spectroscopy ,Renewable Energy, Sustainability and the Environment ,business.industry ,Annealing (metallurgy) ,Composite number ,Analytical chemistry ,Heterojunction ,Polymer solar cell ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Scanning probe microscopy ,Microscopy ,Optoelectronics ,Near-field scanning optical microscope ,business - Abstract
We have studied the effect of annealing process on the performance of photovoltaic devices based on the bulk heterojunction of poly(3-hexylthiophene) and [6,6]-phenyl-C 61 butyric acid methyl ester (P3HT/PCBM). By means of atomic force microscopy (AFM) and scanning of near-field microscopy (SNOM), we can observe the morphology evolution of the annealed P3HT/PCBM composite films. We also studied the changes of optical properties by absorption spectroscopy and the changes of composition distribution of annealed composite films. The results indicate the P3HT in the composite film gradually becomes an ordered structure with annealing. The ordered P3HT facilitates the charge transport. However, the film exhibits a large-scale (1 μm) PCBM aggregation after annealing for an extended period of time. The disrupted bi-continous phase retards the charge transport. Thus, the device efficiency reaches the highest (2.308%) after annealing at 140 °C for 30 min but decreases to 0.810% after 60 min annealing.
- Published
- 2009
33. Nanostructured polymer blends (P3HT/PMMA): Inorganic titania hybrid photovoltaic devices
- Author
-
Wei-Che Yen, Yun-Yue Lin, Yang-Fang Chen, Tsung-Wei Zeng, Chun-Wei Chen, Ming-Chung Wu, Wei-Fang Su, Hsueh-Chung Liao, Hsi-Hsing Lo, and Sharon Chen
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Open-circuit voltage ,Energy conversion efficiency ,Heterojunction ,Polymer solar cell ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Polymer chemistry ,Optoelectronics ,Electrical measurements ,Nanorod ,Polymer blend ,Thin film ,business - Abstract
We have fabricated a photovoltaic (PV) device based on the polymer blends of (poly(3-hexylthiophene) (P3HT)/polymethylmethacrylate (PMMA)) and inorganic TiO 2 nanorod bulk heterojunction. The optimized photovoltaic device with 1.6 wt% PMMA concentration has a power conversion efficiency of 0.65% under simulated AM 1.5 illumination (100 mW/cm 2 ), which is 38% more efficient than the device without the incorporation of PMMA. Furthermore, the PMMA-included device gives a short-circuit current density of 2.57 mA/cm 2 , an open-circuit voltage of 0.53 V, and a fill factor of 0.48. Our studies have shown that having optimal PMMA concentration in the photovoltaic devices helps to smoothen the surface of the hybrid thin film, broaden the absorption spectrum, and improve the electrical conductivity. The results implying improvement in cell performance can be illustrated using atomic force microscopy (AFM), a UV/vis spectrophotometer and electrical measurements.
- Published
- 2009
34. Enhancing light absorption and carrier transport of P3HT by doping multi-wall carbon nanotubes
- Author
-
Ming-Chung Wu, Yang-Fang Chen, Yun-Yue Lin, Yi-Jen Wu, Wei-Fang Su, Chun-Wei Chen, Sharon Chen, and Hsueh-Chung Liao
- Subjects
Materials science ,business.industry ,Atomic force microscopy ,Doping ,Energy conversion efficiency ,General Physics and Astronomy ,Nanotechnology ,Carbon nanotube ,law.invention ,law ,Optoelectronics ,Work function ,Physical and Theoretical Chemistry ,Spectroscopy ,business - Abstract
We have investigated the enhancement of light absorption and carrier transport of poly(3-hexylthiophene) (P3HT) resulted from doping with multi-wall carbon nanotubes (MWNTs). The MWNTs were acid washed first, and then incorporated into P3HT homogenously. The MWNTs make P3HT unfolded with more alignment and thus increase light absorption as shown by the studies of AFM and UV–vis spectroscopy. The KFM data provides useful information to differentiate the work function of the MWNTs from P3HT and further show improved hole transporting behaviors. Based upon these results, the 0.01 wt% MWNTs doped P3HT/PCBM photovoltaic device shows an increase of 29% power conversion efficiency.
- Published
- 2009
35. Polymer solar cells with poly(3,4-ethylenedioxythiophene) as transparent anode
- Author
-
Wei-Fang Su, Yi-Ming Chang, and Leeyih Wang
- Subjects
Materials science ,business.industry ,Energy conversion efficiency ,General Chemistry ,Condensed Matter Physics ,Polymer solar cell ,Electronic, Optical and Magnetic Materials ,law.invention ,Anode ,Biomaterials ,chemistry.chemical_compound ,Photoactive layer ,chemistry ,Polymerization ,PEDOT:PSS ,law ,Solar cell ,Polymer chemistry ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Poly(3,4-ethylenedioxythiophene) - Abstract
A highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) film was prepared by in-situ oxidative polymerization on a glass substrate and adopted as the transparent anode of polymer solar cells that were based on a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM) as the photoactive layer. PEDOT anodes of various thicknesses were prepared for use in such devices. The resistance of the PEDOT and the transmitted light intensity of the irradiation varied with the thickness. The best devices exhibited a power conversion efficiency of 2.6% under simulated AM1.5G solar irradiation. Importantly, the conversion efficiency of incident photons to electrons in the device with the PEDOT anode was comparable to that with an ITO electrode, indicating the practicability of applying PEDOT as anode to fabricate high-efficiency flexible solar cells.
- Published
- 2008
36. Surface plasmon resonance enhanced photoluminescence from Au coated periodic arrays of CdSe quantum dots and polymer composite thin film
- Author
-
Chih-Min Chuang, Ming-Chung Wu, Yang-Fang Chen, Hsi-Hsing Lo, Wei-Fang Su, and Kuo-Chung Cheng
- Subjects
Photoluminescence ,Materials science ,business.industry ,Surface plasmon ,Metals and Alloys ,Analytical chemistry ,Surfaces and Interfaces ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Indium tin oxide ,Quantum dot ,Materials Chemistry ,Optoelectronics ,Surface plasmon resonance ,Thin film ,business ,Luminescence ,Localized surface plasmon - Abstract
ARTICLE I NFO We have fabricated an arrayed CdSe quantum dots composite thin film that can enhance the photo- luminescence of CdSe under the 488 nm laser irradiation by tuning the gold surface plasmon resonance frequency. This thin film consists of a gold coated periodic array of hybrid material of CdSe and poly(methyl methacrylate) on indium tin oxide coated glass substrate. The main surface plasmon resonance was red shifted as we increased the column diameter of the array. By adjusting the column diameters and lattice constants of the array to coincide with the 488 nm excitation wavelength, an evident increase in luminescence intensity was obtained due to the surface plasmon resonance of gold. As a result of likely efficient energy transfer from gold surface plasmon resonance to CdSe, the photoluminescence intensity of CdSe has been increased to 248% at 570 nm. This composite film has many potential applications in high efficient optoelectronic devices.
- Published
- 2008
37. Fadable ink for time–temperature control of food freshness: Novel new time–temperature indicator
- Author
-
Wei-Fang Su and Yulia Galagan
- Subjects
Time temperature indicator ,Temperature control ,Thin layers ,Inkwell ,business.industry ,Substrate (printing) ,Anthraquinone ,Red Color ,chemistry.chemical_compound ,chemistry ,Screen printing ,Composite material ,Telecommunications ,business ,Food Science - Abstract
A novel new colorimetric time–temperature indicator, based on fadable ink has been developed. The printed sign is able to disappear in a defined time period. The color fading is based on the red-ox properties of anthraquinone derivative. Beige anthraquinone β-sulfonate can be easily reduced by sodium hydrosulfite and become red color. By contacting with oxygen, the red color turns back into beige. The time–temperature indicator comprises three thin layers materials either on paper or plastic substrate. The rate of color change is varied by the chemical composition of the polyacrylate. This multilayer structure time–temperature indicator can be easily made by knife coater and screen printing. The made indicator should be very useful to monitor freshness of food.
- Published
- 2008
38. Influence of photo-induced degradation on the optoelectronic properties of regioregular poly(3-hexylthiophene)
- Author
-
Leeyih Wang, Yi-Ming Chang, and Wei-Fang Su
- Subjects
chemistry.chemical_classification ,Materials science ,Photoluminescence ,Renewable Energy, Sustainability and the Environment ,business.industry ,Polymer ,Conjugated system ,Polymer solar cell ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Absorbance ,Crystallinity ,chemistry ,law ,Solar cell ,Optoelectronics ,Absorption (electromagnetic radiation) ,business - Abstract
Recently, head-to-tail regioregular poly(3-hexylthiophene) (P3HT) has been widely used as an active material in fabricating polymer optoelectronic devices. This study employs UV-vis absorption, photoluminescence (PL), X-ray diffraction (XRD) and the space-charge limited current (SCLC) model to elucidate the effect of light illumination on the optic and optoelectronic properties of P3HT. The degraded performance of P3HT, such as low absorbance, PL emission, and charge-carrier mobility is caused mostly by a reduction in the degree of conjugated structure and the lower crystallinity.
- Published
- 2008
39. Wideband Dielectric Resonator Antenna With a Tunnel
- Author
-
Wei-Fang Su, Tze-Hsuan Chang, Yu-Ching Huang, and Jean-Fu Kiang
- Subjects
Optics ,Dielectric resonator antenna ,Materials science ,business.industry ,Q factor ,Electric field ,Bandwidth (signal processing) ,Dielectric resonator ,Electrical and Electronic Engineering ,Wideband ,business ,Polarization (waves) ,Transverse mode - Abstract
A wideband rectangular dielectric resonator (DR) with a horizontal tunnel is proposed. The bandwidth of the TEy 111 mode is increased by using the tunnel to reduce the Q-factor of the DR. As the tunnel height is increased, the electric field distribution of the TEy 112 mode is significantly modified such that its electric field distribution near the top surface of DR is similar to that of the TEy 111 mode, rendering a broadside radiation pattern. The band of the modified TEy 112 mode is merged with that of the TEy 111 mode to achieve a wide bandwidth of 20% (4.765.86 GHz) with broadside radiation pattern of vertical polarization on the xy-plane. The proposed DR antenna can be used in WLAN 802.11a applications.
- Published
- 2008
40. A large interconnecting network within hybrid MEH-PPV/TiO2nanorod photovoltaic devices
- Author
-
Chun-Wei Chen, Hong-Yun Huang, Wei-Fang Su, Tsung-Wei Zeng, Hsi-Hsing Lo, Sz-Chian Liou, Yun-Yue Lin, and Cheng-Hsuan Chen
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Photovoltaic system ,Energy conversion efficiency ,Bioengineering ,Nanotechnology ,General Chemistry ,Photovoltaic effect ,Active layer ,Mechanics of Materials ,Electrode ,Optoelectronics ,General Materials Science ,Quantum efficiency ,Nanorod ,Electrical and Electronic Engineering ,business ,Layer (electronics) - Abstract
This is a study of hybrid photovoltaic devices based on TiO2 nanorods and poly[2-methoxy-5-(2 � -ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). We use TiO 2 nanorods as the electron acceptors and conduction pathways. Here we describe how to develop a large interconnecting network within the photovoltaic device fabricated by inserting a layer of TiO2 nanorods between the MEH-PPV:TiO2 nanorod hybrid active layer and the aluminium electrode. The formation of a large interconnecting network provides better connectivity to the electrode, leading to a 2.5-fold improvement in external quantum efficiency as compared to the reference device without the TiO2 nanorod layer. A power conversion efficiency of 2.2% under illumination at 565 nm and a maximum external quantum efficiency of 24% at 430 nm are achieved. A power conversion efficiency of 0.49% is obtained under Air Mass 1.5 illumination. (Some figures in this article are in colour only in the electronic version)
- Published
- 2006
41. Nanolithography made from water-based spin-coatable LSMO resist
- Author
-
Wei-Fang Su, Chih-Min Chuang, Yu-Ching Huang, Yang-Fang Chen, Kuo-Chung Cheng, Ming-Chung Wu, and Ching-Fu Lin
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Bioengineering ,Nanotechnology ,General Chemistry ,Photoresist ,Polyvinyl alcohol ,chemistry.chemical_compound ,Nanolithography ,Resist ,chemistry ,Mechanics of Materials ,Transmission electron microscopy ,Strontium nitrate ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,Thin film ,business ,Perovskite (structure) - Abstract
A dual functional and water soluble spin-coatable lanthanum strontium manganese oxide (LSMO) resist has been developed that consists of lanthanum nitrate, strontium nitrate, manganese nitrate, polyvinyl alcohol and water. Energetic nitrates plus polyvinyl alcohol fuel promote autoignition and produce nanopatterns (
- Published
- 2006
42. Optical properties and photoconductivity of amorphous silicon carbon nitride thin film and its application for UV detection
- Author
-
Kuei-Hsien Chen, Li-Chyong Chen, Chien-Yu Huang, Wei-Fang Su, Yun Yue Lin, and Chin-Pei Chen
- Subjects
Amorphous silicon ,Materials science ,business.industry ,Mechanical Engineering ,Photoconductivity ,chemistry.chemical_element ,General Chemistry ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,chemistry.chemical_compound ,Optics ,Carbon film ,chemistry ,Plasma-enhanced chemical vapor deposition ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,Thin film ,business ,Carbon ,Carbon nitride - Abstract
Optical properties of amorphous silicon carbon nitride thin films as a function of carbon content have been studied by the spectral microreflectometry. The compositions of a-SiCN thin films deposited with different CH4 flow rates were analyzed by X-ray photoemission spectroscopy (XPS). It was found that the transmittance of a-SiCN thin films decreases with the increasing carbon content; the index of refraction n varies from ~2.0 to ~2.2 and the optical gap (Tauc gap) Eopt value progressively decreases from 4.1 to 3.3 eV while the carbon content changes from 0 to 25% in the films. In addition, a MSM (metal-semiconductor-metal) photodetector device based on the a-SiCN thin film demonstrates excellent selective sensing features with a large photo-to-dark current ratio about 1800 under illumination of the 250 nm UV light source, providing potential applications for low-cost UV detection. D 2004 Elsevier B.V. All rights reserved.
- Published
- 2005
43. Enhanced Efficiency of Hot‐Cast Large‐Area Planar Perovskite Solar Cells/Modules Having Controlled Chloride Incorporation
- Author
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Mercouri G. Kanatzidis, Ma Lin, Che-Pu Hsu, Wei Huang, Wei-Fang Su, Michael R. Wasielewski, Chan Myae Myae Soe, Antonio Facchetti, Hsueh-Chung Liao, Tobin J. Marks, Li Zeng, Binghao Wang, Michael J. Bedzyk, Peijun Guo, and Robert P. H. Chang
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Diffusion ,Energy conversion efficiency ,Nanotechnology ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Coating ,Photovoltaics ,engineering ,Optoelectronics ,General Materials Science ,Crystallite ,Thin film ,0210 nano-technology ,business ,Solution process ,Perovskite (structure) - Abstract
Organic–inorganic perovskite photovoltaics are an emerging solar technology. Developing materials and processing techniques that can be implemented in large-scale manufacturing is extremely important for realizing the potential of commercialization. Here we report a hot-casting process with controlled Cl− incorporation which enables high stability and high power-conversion-efficiencies (PCEs) of 18.2% for small area (0.09 cm2) and 15.4% for large-area (≈1 cm2) single solar cells. The enhanced performance versus tri-iodide perovskites can be ascribed to longer carrier diffusion lengths, improved uniformity of the perovskite film morphology, favorable perovskite crystallite orientation, a halide concentration gradient in the perovskite film, and reduced recombination by introducing Cl−. Additionally, Cl− improves the device stability by passivating the reaction between I− and the silver electrode. High-quality thin films deployed over a large-area 5 cm × 5 cm eight-cell module have been fabricated and exhibit an active-area PCE of 12.0%. The feasibility of material and processing strategies in industrial large-scale coating techniques is then shown by demonstrating a “dip-coating” process which shows promise for large throughput production of perovskite solar modules.
- Published
- 2016
44. Transparent high refractive index nanocomposite thin films
- Author
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Ai Kang Li, Steve Lien-Chung Hsu, Wei-Fang Su, Joseph Lik Hang Chau, Kuo Shin Chang, Yu-Ming Lin, and Tung Lin Li
- Subjects
chemistry.chemical_classification ,Materials science ,Nanocomposite ,High-refractive-index polymer ,business.industry ,Mechanical Engineering ,Tio2 nanoparticles ,Nanoparticle ,Optical transparency ,Nanocomposite thin films ,Polymer ,Condensed Matter Physics ,Optics ,chemistry ,Mechanics of Materials ,General Materials Science ,Composite material ,business ,Refractive index - Abstract
This work reports the preparation of acetic acid-modified TiO2 nanoparticles by sol–gel synthesis method. The nanoparticles can be incorporated directly into the polymer matrix to form transparent high refractive index nanocomposite thin films. The result shows that increasing the titania content in the hybrid nanocomposite thin films can significantly increase the refractive index. Hybrid nanocomposite thin film with refractive index value of 2.38 had been prepared. All prepared films also exhibit excellent optical transparency in the visible region. © 2007 Elsevier B.V. All rights reserved.
- Published
- 2007
45. White light generation with CdSe-ZnS nanocrystals coated on an InGaN-GaN quantum-well blue/Green two-wavelength light-emitting diode
- Author
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Jian-Jang Huang, I-Shuo Liu, Chih-Chung Yang, Wen-Yu Shiao, Horng-Shyang Chen, Wei-Fang Su, Chih-Feng Lu, Chi-Feng Huang, and Dong-Ming Yeh
- Subjects
Diffraction ,Photoluminescence ,Materials science ,business.industry ,Electroluminescence ,Epitaxy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Wavelength ,Optics ,law ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Quantum well ,Light-emitting diode ,Diode - Abstract
We grew and processed a blue/green two-wavelength light-emitting diode (LED) based on the mixture of two kinds of quantum wells (QW) in epitaxial growth. The X-ray diffraction and photoluminescence measurements indicated that the crystalline structure and the basic optical property of individual kinds of QW are not significantly changed in the mixed growth. The relative electroluminescence (EL) intensity of the two colors depends on the injection current level, which controls the hole concentration distribution among the QWs. At low injection levels, the top green-emitting QW dominates in EL. As the injection current increases, the blue-emitting QWs beneath become dominating. We also coated CdSe-ZnS nanocrystals on the top of the two-wavelength LED for converting blue photons into red light. With the coating of such nanocrystals, the device emits blue, green, and red lights for white light generation
- Published
- 2006
46. Control of the color contrast of a polychromatic light-emitting device with CdSe-ZnS nano-crystals on an InGaN-GaN quantum-well structure
- Author
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I-Shuo Liu, Chih-Feng Lu, Chi-Feng Huang, Dong-Ming Yeh, Chih-Chung Yang, Horng-Shyang Chen, Tsung-Yi Tang, Yen-Cheng Lu, Wei-Fang Su, and Jian-Jang Huang
- Subjects
Materials science ,business.industry ,media_common.quotation_subject ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,law ,Contrast (vision) ,Optoelectronics ,Quantum efficiency ,Electrical and Electronic Engineering ,Color contrast ,Colorimetry ,Contact area ,business ,Intensity (heat transfer) ,Quantum well ,Light-emitting diode ,media_common - Abstract
Blue-red polychromatic light-emitting devices are fabricated by attaching red-emitting CdSe-ZnS nano-crystals on a blue-emitting InGaN-GaN multiple-quantum-well (MQW) structure. To improve the red/blue intensity contrast, holes of different diameters are fabricated for increasing the direct contact area between the MQW active regions and CdSe-ZnS nano-crystals. By comparing the devices of 10-, 50-, 60-, and 70-mum hole diameters, and a reference device of no hole, it is found that the hole diameter of 60 mum represents an optimized condition from the viewpoint of maintaining high quantum efficiency. However, the device of 10-mum holes has the highest red/blue intensity ratio, which corresponds to a 36% increase. This result is attributed to its largest side-wall area in the holes among various samples
- Published
- 2006
47. Conjugated polymer/nanoparticles nanocomposites for high efficient and real-time volatile organic compounds sensors
- Author
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Wei-Fang Su, Ming-Chung Wu, Hsueh-Chung Liao, Chun-Fu Lu, and Che-Pu Hsu
- Subjects
Flammable liquid ,Conductive polymer ,Explosive material ,Chemistry ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Nanotechnology ,Chip ,Analytical Chemistry ,chemistry.chemical_compound ,Hazardous waste ,Storage tank ,Current sensor ,Process engineering ,business ,Leakage (electronics) - Abstract
The present work demonstrates a high efficient and low cost volatile organic compounds (VOCs) sensor. Nowadays, VOCs, which are typically toxic, explosive, flammable, and an environmental hazard, are extensively used in R&D laboratories and industrial productions. Real-time and accurately monitoring the presence of harmful VOC during the usage, storage, or transport of VOCs is extremely important which protects humans and the environment from exposure in case of an accident and leakage of VOCs. The present work utilizes conducting polymer/nanoparticles blends to sense various VOCs by detecting the variation of optical properties. The novel sensor features high sensitivity, high accuracy, quick response, and very low cost. Furthermore, it is easy to fabricate into a sensing chip and can be equipped anywhere such as a laboratory or a factory where the VOCs are either used or produced and on each joint between transporting pipes or each switch of VOC storage tanks. Real-time sensing is achievable on the basis of the instant response to VOC concentrations of explosive limits. Therefore, an alarm can be delivered within a few minutes for in time remedies. This research starts from investigating fundamental properties, processing adjustments, and a performance test and finally extends to real device fabrication that practically performs the sensing capability. The demonstrated results significantly advance the current sensor technology and are promising in commercial validity in the near future for human and environmental safety concerns against hazardous VOCs.
- Published
- 2013
48. Low-temperature solution processable n–i–p perovskite solar cell
- Author
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Wei-Fang Su, Chih Yu Chang, and Cheng Ya Chu
- Subjects
Materials science ,Fabrication ,business.industry ,Energy conversion efficiency ,General Engineering ,General Physics and Astronomy ,Perovskite solar cell ,Heterojunction ,Nanotechnology ,02 engineering and technology ,Hybrid solar cell ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polymer solar cell ,0104 chemical sciences ,Optoelectronics ,0210 nano-technology ,business ,Solution process ,Perovskite (structure) - Abstract
Recently, the perovskite solar cells draw lots of attentions because of low cost, solution-processable and promising high efficiency. The power conversion efficiency (PCE) is rapidly reached to a certified value of 20.1%. However, the conventional electron transport layer (ETL) of the device needs to be sintered over 500 °C which is high energy-consumption process and cannot use on flexible substrate. Therefore, many research groups endeavor to develop low-temperature solution processable electron transport material in perovskite solar cells. In this review, we present systematic and critical discussions on the evolution of perovskite solar cells from meso-superstructure solar cells (MSSCs) to low-temperature solution processed planar heterojunction (PHJ) perovskite solar cells. This review will provide a guideline for the fabrication of high PCE perovskite solar cell using solution process at temperature of 150 °C or under, which has potential to achieve large scale fabrication by roll-to-roll technique for commercial products in near future.
- Published
- 2016
49. Nanoparticle-tuned self-organization of a bulk heterojunction hybrid solar cell with enhanced performance
- Author
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Wei-Fang Su, Hsueh-Chung Liao, Chun-Jen Su, Yang-Fang Chen, Tsung-Han Lin, Sheng-Yong Chang, U-Ser Jeng, Chih-Min Chuang, Cheng-Si Tsao, Yu-Tsun Shao, Meng-Huan Jao, Yu-Ching Huang, and Charn-Ying Chen
- Subjects
Electron mobility ,Nanostructure ,Materials science ,business.industry ,General Engineering ,General Physics and Astronomy ,Nanoparticle ,Nanotechnology ,Hybrid solar cell ,Polymer solar cell ,Amorphous solid ,law.invention ,law ,Solar cell ,Optoelectronics ,Grazing-incidence small-angle scattering ,General Materials Science ,business - Abstract
We demonstrate here that the nanostructure of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT/PCBM) bulk heterojunction (BHJ) can be tuned by inorganic nanoparticles (INPs) for enhanced solar cell performance. The self-organized nanostructural evolution of P3HT/PCBM/INPs thin films was investigated by using simultaneous grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence wide-angle X-ray scattering (GIWAXS) technique. Including INPs into P3HT/PCBM leads to (1) diffusion of PCBM molecules into aggregated PCBM clusters and (2) formation of interpenetrating networks that contain INPs which interact with amorphous P3HT polymer chains that are intercalated with PCBM molecules. Both of the nanostructures provide efficient pathways for free electron transport. The distinctive INP-tuned nanostructures are thermally stable and exhibit significantly enhanced electron mobility, external quantum efficiency, and photovoltaic device performance. These gains over conventional P3HT/PCBM directly result from newly demonstrated nanostructure. This work provides an attractive strategy for manipulating the phase-separated BHJ layers and also increases insight into nanostructural evolution when INPs are incorporated into BHJs.
- Published
- 2012
50. Single-electron transistors and memory cells with Au colloidal islands
- Author
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Chii-Dong Chen, Wei-Fang Su, S. M. Shih, and Cen-Shawn Wu
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Transistor ,Monte Carlo method ,Coulomb blockade ,Nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,law.invention ,Single electron ,Hysteresis ,Colloid ,law ,Optoelectronics ,business ,Lithography ,Electron-beam lithography - Abstract
In this study, single-electron transistors and memory cells with Au colloidal islands linked by C60 derivatives have been fabricated by hybridization of top–down advanced electron-beam lithography and bottom–up nanophased-material synthesis techniques. Low-temperature transport measurements exhibit clear Coulomb-blockade-type current–voltage characteristics and hysteretic-type gate-modulated current. The hysteresis is attributed to the presence of electrically isolated charge–storage islands. With the guidance provided by Monte Carlo simulation, we propose a circuit model and give an estimate of the sample parameters.
- Published
- 2002
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