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Photon-induced trap deactivation is commonly observed in organometal halide perovskites. Trap deactivation is characterized by an obvious photoluminescence (PL) enhancement. In this work, the properties of traps in CH3NH3PbI3 perovskite films were studied based on the PL enhancement excited by lasers of different wavelengths (633 nm and 405 nm). Two types of electron traps were identified; one can be deactivated by both 633 nm and 405 nm illuminations, whereas the other one can only be deactivated by 405 nm illumination. The energy levels of both types of traps were beneath the conduction band minimum. The expressions of the PL enhancement kinetics due to the trap deactivations by lasers of different wavelengths were derived. The ratio of the constants of the radiative recombination rate and the initial capture rates for both traps was determined from the PL enhancement. The trap deactivation was a photon-related process rather than a photocarrier-related process, and the deactivation time was inversely proportional to the photon flux density.

Atmospheric thermal assisted blade coating (TABC) method, which is quick film crystallization and easier fabrication than the commonly used spin-coating process, to prepare a high quality CH3NH3PbI3 perovskite film is investigated in this work. Selection of the perovskite precursor solvents and controlling the ratio of the mixed solvent as well as substrate temperature for perovskite film formation are important factors in this TABC process. Based on the results obtained in this work, substrate temperature is the key factor for managing the perovskite film phase transition which influences the film roughness and crystallinity. Furthermore, the high-quality perovskite films are prepared by perovskite precursors with mixture of solvents containing GBL/DMSO at the ratio from 1/9 to 5/5. By using the optimum substrate temperature of 130 °C and the GBL/DMSO solvent ratio of 1/9 (G01D09) for the preparation of small area n-i-p and p-i-n PSCs as well as the p-i-n type perovskite sub-module, the power conversion efficiencies of 17.55%, 16.90% and 13.03%, respectively, are acquired under the illumination of 100 mW/cm2 (AM 1.5G).

Perovskite solar cells (PSCs) have earned considerable attention and are candidates against the inevitable energy crisis. Even though various successful PSCs have emerged, increasing the PCE by reinforcing charge collection is still a critical issue. The manipulation of carriers between the perovskite active layer and the electron extraction layer (EEL) is essential. Here, we prepared a tin-doped TiO2 (Sn/TiO2) EEL that presented two main polymorphs, anatase and rutile, and successfully fabricated a high-performance planar PSCs. Besides, the band alignment between EEL and perovskite active layer could be optimized by tuning the Sn doping concentration and the ratio of anatase and rutile phases. The intrinsic conductivity, interface morphology, band alignment, and charge carrier dynamic were characterized and the relationship to the photovoltaic performance was clarified. As the Sn ions being doped into TiO2 structure, EEL presented the mixed TiO2 rutile/anatase phase, directly narrowing the bandgap and promoting mobility. Furthermore, the adjustment of the band structure can facilitate electronic transitions. Finally, a promising planar PSC with Sn/TiO2 phase junction EEL achieved a champion PCE of 15.4%.

CF4 plasma treatment on n+-Si wafers as bottom electrodes (BEs) of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) metal-ferroelectric-metal (MFM) capacitors has been investigated in this study. Prior to the fabrication of MFM capacitors, comprehensive material analyses are administered to identify the incorporation of fluorine atoms into P(VDF-TrFE) copolymers, revealing an enrichment in C2HF3 (trifluoroethylene) bonds and an improvement in the crystallinity of the film. The P(VDF-TrFE) MFM capacitors with CF4-plasma-treated n+-Si wafers show a shallower charge trapping level of 0.154–0.226 eV extracted from the Frenkel–Poole (F–P) emission at 213–273 K for the BE injection compared to that for the top electrode (TE) injection, which is ascribed to the passivation of deep traps by the fluorine atoms that diffused from the n+-Si wafers. Thus, asymmetric remanent polarization and a negative internal bias field are obtained because of the significant increase in the β-phase at the bottom of the P(VDF-TrFE) films. With the CF4 plasma treatment for 1 min, the P(VDF-TrFE) MFM capacitors demonstrate a remanent polarization (2Pr) of 6.58 µC/cm2, a coercive electric field (Ec) of 0.47 MV/cm and stability for more than 3 × 104 cycles with negligible fatigue, making the fluorine-incorporated P(VDF-TrFE) copolymers suitable for future high-performance nonvolatile memory applications.

This study improved quality of CH3NH3PbI3 (MAPbI3) perovskite films by delaying thermal annealing in the spin coating process and introducing KI and I2 to prepare MAPbI3 films that were low in defects for high-efficiency perovskite solar cells. The influences of delayed thermal annealing time after coating the MAPbI3 perovskite layer on the crystallized perovskite, the morphology control of MAPbI3 films, and the photoelectric conversion efficiency of solar cells were investigated. The optimal delayed thermal annealing time was found to be 60 min at room temperature. The effect of KI/I2 additives on the growth of MAPbI3 films and the corresponding optimal delayed thermal annealing time were further investigated. The addition of KI/I2 can improve perovskite crystallinity, and the conductivity and carrier mobility of MAPbI3 films. Under optimized conditions, the photoelectric conversion efficiency of MAPbI3 perovskite solar cells can reach 19.36% under standard AM1.5G solar illumination of 100 mW/cm2.

Volatile organic compounds (VOCs) are organic chemicals having a high vapor pressure at room temperature. Chronic exposure to VOC vapor can be potentially dangerous to human health. In this study, we build a high-performance freestanding aligned Ag/CdSe-CdS/poly(methyl methacrylate) (PMMA) texture to detect VOC vapors. The insight of this new VOC-sensing material is based on electrospinning techniques, ultraviolet (UV)/ozone treatments, and nano-optics. The incorporation of CdSe-CdS core-shell quantum rods (QR) and silver nanocrystals in the PMMA nanofibers amplifies the polarization response of long rods in VOC detection, thus increasing the sensitivity of VOC-sensing materials. Further, the uniaxial aligned Ag/QR/PMMA sensing material was treated by UV-ozone etching to increase surface absorption. The advanced double-sided UV-ozone etching on the uniaxial aligned Ag/QR/PMMA efficiently enhanced the extinction changes of VOCs. Two categories of solvents, typical VOCs and alcoholic VOCs, were put into practical tests for the Ag/QR/PMMA VOC-sensing materials. The Ag/QR/PMMA reached the detection limit for 100 ppm butanol within 1 min. The freestanding aligned Ag/CdSe-CdS/PMMA texture is a newly designed nanocomposite device for environmental risk monitoring. It can be accepted by the market compared to the other highly sensitive commercial VOC-sensing materials.

Organic-inorganic hybrid perovskite solar cells (PSCs), a superstar of photovoltaic devices, have attracted people’s attention owing to their adjustable energy band gap value, extremely high absorption coefficient, long charge carrier diffusion length, and dramatically high power conversion efficiency. In recent years, researchers have tried hard to explore new strategies in order to obtain better optical characteristics. Metal ion-doped electron transport layer (ETL) is a convenient way to improve the optical properties of PSCs. By this method, the conduction band and valence band position can be changed. This can lead to the carriers can effectively transport, and the charge recombination between ETL and absorber layer be reduced. In our study, we have enhanced the photovoltaic performance and the hysteresis behavior of the device by using various concentrations of mesoscopic Ag-doped TiO2 (meso-Ag:TiO2) as the ETL. We also systematically discussed the surface morphology, the charge carrier dynamic, the electron mobility, and the electrical conductivity for our devices. Finally, by optimizing the parameters of PSCs and the energy band alignment between perovskite absorber layer and ETL, the power conversion efficiency (PCE) of the champion device with 1.00 mol% meso-Ag:TiO2 ETL reached as high as 17.7%.

Photon-induced trap deactivation is commonly observed in organometal halide perovskites. Trap deactivation is characterized by an obvious photoluminescence (PL) enhancement. In this work, the properties of traps in CH3NH3PbI3 perovskite films were studied based on the PL enhancement excited by lasers of different wavelengths (633 nm and 405 nm). Two types of electron traps were identified; one can be deactivated by both 633 nm and 405 nm illuminations, whereas the other one can only be deactivated by 405 nm illumination. The energy levels of both types of traps were beneath the conduction band minimum. The expressions of the PL enhancement kinetics due to the trap deactivations by lasers of different wavelengths were derived. The ratio of the constants of the radiative recombination rate and the initial capture rates for both traps was determined from the PL enhancement. The trap deactivation was a photon-related process rather than a photocarrier-related process, and the deactivation time was inversely proportional to the photon flux density.

The rapid development of machine learning has proven its potential in material science. To acquire an accurate and promising result, the choice of descriptor plays an essential role in dictating the model performance. In this work, we introduce a set of novel descriptors, Element Code, which is generated from pseudopotential. Using a variational autoencoder to perform unsupervised learning, the produced Element Code is verified to contain representative information on elements. Attributed to the successful extraction of information from pseudopotential, Element Code can serve as the primary descriptor for the machine learning model. We construct a model using Element Code as the sole descriptor to predict the bandgap of a lead-free double halide perovskite, and an accuracy of 0.951 and mean absolute error of 0.266 eV are achieved. We believe our work can offer insights into selecting lead-free halide perovskites and establish a paradigm of exploring new materials.

The perovskite solar cells (PSCs), bearing advantages including low cost of materials and solution process and high power conversion efficiency, have drawn intensive attention. Alkaline earth metal can replace the toxic lead in the perovskite-structured absorber (PSA) due to the approximate ionic radius. Some of these metals can fit an octahedral factor and Goldschmidt’s tolerance factor. In this study, we partially replaced various alkaline earth metals (such as Mg, Ca, Sr, and Ba) for lead. We found that Ba was most suitable for Pb replacement in PSA and exhibited the highest photovoltaic performance. In addition, we adopted the various hole blocking layers (HBLs), including pristine TiO2, Ag-doped TiO2, and Zn-doped TiO2, to enhance the photovoltaic performance. Furthermore, we replaced gold with silver for the electrode material of n–i–p PSCs, because silver exhibits high conductivity and can drastically reduce manufacturing costs. We systematically studied the photovoltaic effects of the various amou...

Black TiO2 nanoparticles (BTN) was prepared by sol-gel derived precursor calcined in an argon atmosphere. The synthesized BTN with trivalent titanium ion, structural defect, and oxygen vacancy shows a remarkably high absorbance in the visible light spectrum. BTN thus behaves a higher visible-active nanoreactor than white TiO2 nanoparticles (WTN) in the aqueous solution for organic pollutant degradation. Moreover, palladium decoration on the BTN surface (Pd-BTN) demonstrates a fascinating clean energy application. The obtained Pd-BTN fulfills a satisfied green material demand in the photocatalytic hydrogen production application. Pd-BTN calcined at 400 °C (Pd-BTN-400) shows the high photocatalytic hydrogen generation rate of 5200 μmol/g h under UV-A irradiation and 9300 μmol/g h under UV-B irradiation, respectively. The well-developed material, Pd-BTN-400, could be one of the best solutions in the concern of clean energy and water-purification with regard to the continuous environmental issue.

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%.

Perovskite solar cell is a novel photovoltaic technology with the superior progress in efficiency and the simple solution processes. Develop lead-free or lead-reduced perovskite materials is a significant concern for high-performance perovskite solar cell. Among the alkaline earth metals, the Sr2+ and Ba2+ are suitable for Pb2+ replacement in perovskite film due to fitting Goldschmidt's tolerance factor. In this study, we adopted Ba-doped and Sr-doped perovskite structured materials with different doping levels, including 1.0, 5.0, and 10.0 mol%, to prepare perovskite solar cells. Both Ba-doped and Sr-doped perovskite structured materials have a related tendency in absorption behavior and surface morphology. At 10.0 mol% doping level, the power conversion efficiency (PCE) of Sr-doped perovskite solar cells is only ∼0.5%, but the PCE of Ba-doped perovskite solar cells can be achieved to ∼9.7%. Ba-doped perovskite solar cells showed the acceptable photovoltaic characteristics than Sr-doped perovskite solar cells. Ba dopant can partially replace the amount of lead in the perovskite solar cells, and it could be a potential candidate in the field of lead-free or lead-reduced perovskite energy materials.

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.

Volatile organic compounds (VOCs) sensors are the imperative technology of modern life for environmental monitoring to detect any harmful elements and to prevent lethal exposure. The sensing material is a fibrous film consisting of poly(3-hexylthiophene)(P3HT)/poly(methyl methacrylate)(PMMA) blend, and it is fabricated on a glass substrate. The P3HT/PMMA fibrous film is made by electrospinning process and shows high specific surface for solvent vapor harvesting. The P3HT/PMMA fibrous films are thus easily designed according to the extinction changes of VOCs. The P3HT/PMMA fibrous film exhibits the detection capability for VOCs. It satisfies the detection limit of acetone, toluene and o-xylene at 500 ppm. The cost of the P3HT/PMMA fibrous film is acceptable to the market in contrast to the commercial sensors toward VOCs.

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.

In present work, we focused on the improvement of short-circuit current density (J sc ) by using zinc-doped TiO 2 (Zn-doped TiO 2 ) as electron transport layer. Various Zn-doped TiO 2 compact layers with different doping concentrations are prepared by sol-gel method followed thermal treatment, and they were then used to fabricate perovskite solar cell. Effects of zinc (Zn) on the power conversion efficiency (PCE), absorption behavior, crystal structure, electrical conductivity, and surface morphology are systemically elucidated. Charge carrier dynamics between perovskite active layer and titanium dioxide (TiO 2 ) compact layer is discussed too. When the dopant concentration is less than 5.0 mol%, the absorption behavior, electrical conductivity and charge separation efficiency increase with Zn doping concentration. In contrast, when the Zn dopant is 7.0 mol%, it results in the decay of these properties mentioned. According to the optimized processing of perovskite solar cells, the J sc is increased from 18.5 to 22.3 mA/cm 2 so as to the PCE is significantly improved from 11.3% to 14.0%.

Piezoresistive pressure sensors have garnered significant attention because of their wide applications in automobiles, intelligent buildings, and biomedicine. For in vivo testing, the size of pressure sensors is a vital factor to monitor the pressure of specific portions of a human body. Therefore, the primary focus of this study is to miniaturize piezoresistive pressure sensors with graphene oxide (GO)-incorporated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite films on a flexible substrate for biomedical applications. Prior to the fabrication of pressure sensors, a comprehensive material analysis was applied to identify the horizontal placement of GO flakes within the PEDOT:PSS copolymers, revealing a reduction in variable range hopping distance and an enhancement in carrier mobility. For devices scaled to 0.2 cm, the sensitivity of PEDOT:PSS pressure sensors was conspicuously decreased owing to the late response, which can be effectively solved by GO incorporation. Using technology computer-aided design simulations, the current crowded at the PEDOT:PSS film surface and in the vicinity of an indium-tin-oxide electrode corner was found to be responsible for the changes in piezoresistive behaviors of the scaled devices. The miniaturized flexible piezoresistive pressure sensors with PEDOT:PSS/GO composite films are capable of monitoring the brain pressure of intracranial surgery of a rat and discerning different styles of music for a potential application in hearing aids.

In recent years, organometal halide perovskite solar cells (PSCs) have been developed rapidly. To promote commercialization, certain critical issues have to be resolved, for instance, the lack of stability while exposing to moisture, heat, and light. One of the solutions to improve stability is the lower dimension perovskite structure. The high stability of the two-dimensional (2D) perovskite structure can be ascribed to its long-chain organic molecules. In this study, the thermal assisted blade coating method was used to prepare high-quality and pinhole-free perovskite film. We prepared 2D perovskite solutions and fabricated quasi-2D/3D perovskite films with various 2D perovskite solution concentrations. Moreover, we conducted temperature-dependent PL spectra to estimate the exciton binding energies of quasi-2D/3D perovskite film. Finally, our PSC device achieved a power conversion efficiency of 20.26% and possessed long-term ambient stability.

Layer-dependent solvent vapor annealing (LDSVA) treatment using dimethylformamide (DMF) vapor on specific layers of stacked poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymers by metal-ferroelectric-metal (MFM) capacitors and nanogenerators was investigated in this study. Prior to the fabrication of the devices, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) were performed to analyze the polarization of the crystalline β-phase in LDSVA-treated stacked P(VDF-TrFE) copolymers. After the LDSVA treatment on the top and bottom of the stacked films, the ferroelectric properties of P(VDF-TrFE) MFM capacitors became asymmetric. This can be confirmed via the bias electric field (Ebias) and non-switchable leakage current due to the non-uniform distribution of polarized dipoles. With an increase in LDSVA treatment time, the arrangement of polarized dipoles in stacked P(VDF-TrFE) copolymers was significantly enhanced, especially the samples with the treatment on the bottom of the stacked films, contributing to a large remnant polarization (2Pr) and a low coercive electric field (Ec) of the MFM capacitors. Additionally, the piezoelectric nanogenerators with LDSVA treatment on stacked P(VDF-TrFE) copolymers presented a large open-circuit output voltage of more than 4.02 V at 7 Hz under an applied force of 800 g, which is approximately 3 times larger than that of the samples without treatment. The LDSVA-treated stacked P(VDF-TrFE) copolymers with superior ferroelectric and nanogenerator behaviors exhibit good potential with regard to highly efficient energy harvesting applications.

Perovskite solar cells (PSCs) have earned widespread attention owing to its fast-growing power conversion efficiency (PCE). However, there are some challenges for this type of solar cells. The toxicity issue, current density-voltage (J-V) hysteresis, and uncertain stability hinder commercialization. In this study, we developed the PSCs with MA0.4FA0.6BaxPb1-xIyCl3-y film as active layer. The MA0.4FA0.6BaxPb1-xIyCl3-y film with various barium doping concentrations were fabricated by solvent engineering method. We investigate the surface morphology, crystal orientation, and optical property of various perovskite films. Furthermore, the in situ grazing-incidence wide-angle X-ray scattering (in-situ GIWAXS) is used to analyze the heating crystallization process of perovskite film. We discover that Ba can improve crystallinity and structural stability. For the optimal 5.0 mol% Ba replacement, the PCE of perovskite device is increased to 17.4%, the J-V hysteresis can be completely eliminated and the device demonstrates long-term stability.

Volatile organic compounds (VOCs) are potentially dangerous to the environment and human health. The developed sensing template in this study was prepared by a one-step process on a glass substrate using the electrospinning technique. The sensing material made of the uniaxial aligned CdSe-CdS/Ag/PMMA composite scaffold consists of CdSe-CdS core-shell quantum rods, silver nanoparticles (Ag NPs), and poly(methyl methacrylate) (PMMA) nanofibers. Increasing the specific surface area is beneficial for VOCs harvesting; therefore, the uniaxial aligned CdSe-CdS/Ag/PMMA composite scaffold was slightly treated with UV-ozone etching, and thus efficiently enhancing the extinction changes of VOCs. Also, a high VOC detection capability was demonstrated by the polarization response and Ag surface plasmon resonance of the nanocomposite. A series of typical VOCs and alcoholic VOCs were used for the VOCs sensor practical tests. This VOC sensor achieved a spectacular detection limit of 100 ppm for butanol and 500 ppm for chlorobenzene. The uniaxial aligned CdSe-CdS/Ag/PMMA composite scaffold is a newly designed nanocomposite and can reach the market demands comparing to other commercial high sensitive VOC sensors.

Piezoelectric pressure sensing behaviors of high-density and low-damage CF4-plasma-treated indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) coated by poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) films have been investigated. The CF4 plasma treatment was performed on the IGZO channel by using an inductively coupled plasma (ICP) system with a quartz filter. Prior to the fabrication of devices, X-ray diffractometer (XRD) and atomic force microscopy (AFM) were applied to identify the enhancement in the crystallinity of P(VDF-TrFE) films on the plasma-fluorinated IGZO films. With the analyses of X-ray photoelectron spectroscopy (XPS), it is proved that the fluorine radicals reacted with the metal-oxygen bonds will increase the oxygen vacancies in IGZO films, contributing to an enhancement in field effect mobility (μFE) and drain current (IDS) of IGZO TFTs. Furthermore, the fluorine atoms diffused from the IGZO channel into the bottom SiO2 layer were confirmed by secondary ion-mass spectroscopy (SIMS), reducing the interfacial and oxide charges of the devices for a negative shift in threshold voltage (Vt). Under a 0.5-kg applied force press/release cyclic test, a 4.8-fold increase in drain current response of 1-min CF4-plasma-treated piezoelectric pressure sensors was optimized, because of the enhanced electrical behaviors of IGZO TFTs and an increase in aligned dipole moments of P(VDF-TrFE) copolymers. The promising results make the piezoelectric pressure sensors with high-density and low-damage CF4-plasma-treated IGZO TFTs coated by P(VDF-TrFE) copolymer suitable for future high-performance tactile sensing applications.

In this study, the cross-talk effects and the basic piezoresistive characteristics of gold nanoparticle (Au-NP) incorporated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) pressure sensing 2 × 2 arrays are investigated using a cross-point electrode (CPE) structure. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) mappings were carried out to confirm the incorporation of Au-NPs in the PEDOT:PSS films. A solution mixing process was employed to incorporate the nanoparticles. When the diameter of the Au-NPs incorporated in the PEDOT:PSS films (Au-NPs/PEDOT:PSS) was 20 nm, the piezoresistive pressure sensing 2 × 2 arrays were almost immune to cross-talk effects, which enhances the pressure sensing accuracy of the array. The Au-NPs render the PEDOT:PSS films more resilient. This is confirmed by the high plastic resistance values using a nanoindenter, which reduce the interference between the active and passive cells. When the size of the Au-NPs is more than 20 nm, a significant cross-talk effect is observed in the pressure sensing arrays as a result of the high conductivity of the Au-NPs/PEDOT:PSS films with large Au-NPs. With the incorporation of optimally sized Au-NPs, the PEDOT:PSS piezoresistive pressure sensing arrays can be promising candidates for future high-resolution fingerprint identification system with multiple-electrode array structures.

Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is a co-planar interferometer array operating at a wavelength of 3mm to measure the Sunyaev-Zeldovich effect (SZE) of galaxy clusters. In the first phase of operation -- with a compact 7-element array with 0.6m antennas (AMiBA-7) -- we observed six clusters at angular scales from 5\arcmin to 23\arcmin. Here, we describe the expansion of AMiBA to a 13-element array with 1.2m antennas (AMiBA-13), its subsequent commissioning, and our cluster SZE observing program. The most important changes compared to AMiBA-7 are (1) array re-configuration with baselines ranging from 1.4m to 4.8m covering angular scales from 2\arcmin to 11.5\arcmin, (2) thirteen new lightweight carbon-fiber-reinforced plastic (CFRP) 1.2m reflectors, and (3) additional correlators and six new receivers. From the AMiBA-13 SZE observing program, we present here maps of a subset of twelve clusters. In highlights, we combine AMiBA-7 and AMiBA-13 observations of Abell 1689 and perform a joint fitting assuming a generalized NFW pressure profile. Our cylindrically integrated Compton-y values for this cluster are consistent with the BIMA/OVRA, SZA, and Planck results. We report the first targeted SZE detection towards the optically selected galaxy cluster RCS J1447+0828, and we demonstrate the ability of AMiBA SZE data to serve as a proxy for the total cluster mass. Finally, we show that our AMiBA-SZE derived cluster masses are consistent with recent lensing mass measurements in the literature., 21 pages, 19 figures; Accepted by ApJ; Comparison between AMiBA-SZE and lensing masses has been newly included in the accepted version

In this study, we developed a novel sensing material fabricated using a poly(3-hexylthiophene) (P3HT)/poly(methyl methacrylate) (PMMA) blend fiber on a glass substrate. The sensing materials can easily be used for sensing toluene vapor detected from extinction spectral changes. The extinction spectra variation is noted from the absorption of volatile organic compounds in a highly specific surface area of fibrous coating. An electrospinning technique is applied to generate a nonwoven structure and uniaxial orientation by fibrous coating. The response of the uniaxially orientated fibrous film is even improved at several toluene vapor concentrations. The best detection limit of this well-aligned fibrous film is up to 200 ppm for toluene vapor.

Many organic/inorganic nanocomposites have been fabricated into fibrous materials using electrospinning techniques, because electrospinning processes have many attractive advantages and the ability to produce relatively large-scale continuous films. In this study, the polyvinyl alcohol (PVA)/silk/titanium dioxide ( TiO 2) nanocomposite self-cleaning textiles were successfully produced using electrospinning technique. After optimizing electrospinning conditions, we successfully obtained the PVA/silk/ TiO 2 nanocomposite fibers with average diameter of ∼220 nm and TiO 2 concentration can be as high as 18.0 wt.%. For the case of the PVA/silk/ TiO 2 nanocomposite textile, the color of brilliant green coated on the textile surface changed from the initial green color to colorless after ultraviolet (UV) irradiation. Because of its worthy photocatalytic performance, the developed PVA/silk/ TiO 2 nanocomposite materials in this study will be beneficial for the design and fabrication of multifunctional fibers and textiles.