Search

The objective of this study is to create a planar solar light absorber that exhibits exceptional absorption characteristics spanning from visible light to infrared across an ultra-wide spectral range. The eight layered structures of the absorber, from top to bottom, consisted of Al2O3, Ti, Al2O3, Ti, Al2O3, Ni, Al2O3, and Al. The COMSOL Multiphysics® simulation software (version 6.0) was utilized to construct the absorber model and perform simulation analyses. The first significant finding of this study is that as compared to absorbers featuring seven-layered structures (excluding the top Al2O3 layer) or using TiO2 or SiO2 layers as substituted for Al2O3 layer, the presence of the top Al2O3 layer demonstrated superior anti-reflection properties. Another noteworthy finding was that the top Al2O3 layer provided better impedance matching compared to scenarios where it was absent or replaced with TiO2 or SiO2 layers, enhancing the absorber's overall efficiency. Consequently, across the ultra-wideband spectrum spanning 350 to 1970 nm, the average absorptivity reached an impressive 96.76%. One significant novelty of this study was the utilization of various top-layer materials to assess the absorption and reflection spectra, along with the optical-impedance-matching properties of the designed absorber. Another notable contribution was the successful implementation of evaporation techniques for depositing and manufacturing this optimized absorber. A further innovation involved the use of transmission electron microscopy to observe the thickness of each deposition layer. Subsequently, the simulated and calculated absorption spectra of solar energy across the AM1.5 spectrum for both the designed and fabricated absorbers were compared, demonstrating a match between the measured and simulated results. [ABSTRACT FROM AUTHOR]

Owing to its contribution to carbon emission reduction, green energy has received widespread attention. Among green energy sources, solar energy is regarded as the most important. In solar energy production, dye-sensitized solar cells (DSSCs) have been favored owing to their characteristics of simple manufacturing and high efficiency as a third-generation solar cell technology. DSSCs are prospective candidates for powering indoor Internet of Things (IoT) devices. In this study, to find a method to enhance DSSCs' efficiency, the advantages and disadvantages of the screen printing method and the mechanical pressing and annealing method were analyzed. Using an improved method, a TiO2 photoanode was processed and annealed, and the DSSCs with the photoanode showed an efficiency increase from 1.10 to 4.78%. [ABSTRACT FROM AUTHOR]

In the context of ZnO nanorods (NRs) grown on Si and indium tin oxide (ITO) substrates, this study aimed to compare their degradation effect on methylene blue (MB) at different concentrations. The synthesis process was carried out at a temperature of 100 °C for 3 h. After the synthesis of ZnO NRs, their crystallization was analyzed using X-ray diffraction (XRD) patterns. The XRD patterns and top-view SEM observations demonstrate variations in synthesized ZnO NRs when different substrates were used. Furthermore, cross-sectional observations reveal that ZnO NRs synthesized on an ITO substrate exhibited a slower growth rate compared to those synthesized on a Si substrate. The as-grown ZnO NRs synthesized on the Si and ITO substrates exhibited average diameters of 110 ± 40 nm and 120 ± 32 nm and average lengths of 1210 ± 55 nm and 960 ± 58 nm, respectively. The reasons behind this discrepancy are investigated and discussed. Finally, synthesized ZnO NRs on both substrates were utilized to assess their degradation effect on methylene blue (MB). Photoluminescence spectra and X-ray photoelectron spectroscopy were employed to analyze the quantities of various defects of synthesized ZnO NRs. The effect of MB degradation after 325 nm UV irradiation for different durations can be evaluated using the Beer–Lambert law, specifically by analyzing the 665 nm peak in the transmittance spectrum of MB solutions with different concentrations. Our findings reveal that ZnO NRs synthesized on an ITO substrate exhibited a higher degradation effect on MB, with a rate of 59.5%, compared to NRs synthesized on a Si substrate, which had a rate of 73.7%. The reasons behind this outcome, elucidating the factors contributing to the enhanced degradation effect are discussed and proposed. [ABSTRACT FROM AUTHOR]

In this study, evolutionary game theory was applied to construction safety management as an innovative research methodology in the discourse of construction management. The authors demonstrated that the principal contractor and construction employees are important stakeholders in construction safety management. The research results presented in this Special Issue deal with different topics, including building construction, design, implementation, and their effects, particularly how resources are saved, reused, and recycled in building construction. Monitoring and improving the environment in the building for human activities contributed to circular building design and construction significantly. [Extracted from the article]

A simple and low-cost fabrication method of dye-sensitized solar cells (DSSCs) was developed to improve the structure and performance of the photoanode with the pressed layer and compact TiO2 thin film using spin coating, screen printing, and mechanical compression. In this study, four different TiO2 layers were adopted to fabricate photoanodes: a mesoporous TiO2 nanoparticles (NPs) layer, a pressed TiO2 NPs layer, a mesoporous TiO2 NPs layer on the TiO2 compact thin film, and a pressed TiO2 NPs layer on the TiO2 compact thin film. The compact thin film was deposited on the fluorine-doped tin oxide (FTO) glass via spin coating, while the mesoporous TiO2 NPs layer was deposited via the screen-printing method. The pressed TiO2 NPs layer was produced by compressing the mesoporous TiO2 NPs layer with a hydraulic press machine. When using the pressed TiO2 NPs layer for the photoanode of DSSC, the power conversion efficiency of DSSC was enhanced the most. The electron lifetime for DSSC with photoanodes based on the pressed TiO2 NPs and mesoporous TiO2 NPs layers were 8.217 and 6.287 ms, respectively. The power conversion efficiency of DSSC with photoanodes based on the pressed TiO2 NPs layer was 5.4%, while that based on the mesoporous TiO2 NPs layer was 4.08%. DSSC with photoanodes based on the pressed TiO2 NPs layer showed a significant increase in the power conversion efficiency by 36.16% compared to that based on the mesoporous TiO2 NPs layer. [ABSTRACT FROM AUTHOR]

Human–computer interaction (HCI) research involves the design and use of computer technology, focusing in particular on the interfaces between people (users) and computers. HCI researchers observe the ways in which humans interact with computers and design technologies that allow them to interact in novel ways. As HCI evolves into HCI 2.0, user experiences and feedback become ever more relevant. This Special Issue, "Human Computer Interactions 2.0", presents 11 excellent papers about topics related to human–computer interactions. It aims to provide a broad international forum for world researchers, engineers and professionals in human–computer interaction research for the discussion and exchange of various scientific, technical and management discoveries across the world. [ABSTRACT FROM AUTHOR]

Many countries aim to promote low-carbon and eco-friendly development and find a route to sustainable development. For such development, a model that helps design and build appropriate constructions is necessary. Thus, this study is carried out to establish such a model by combining the Delphi method, analytical hierarchy process (AHP), and fuzzy logic theory (FLT) (DAFuzzy model). In the Delphi method, the expert's opinions are reflected in three dimensions (green facilities, ecological facilities, and community participation) and nine factors (green building materials, photovoltaic power generation, energy-saving equipment (green facilities), green roof, planting/vegetation, rainwater collection/water recycling (ecological facilities), subsidies, resident participation, appropriate norms (community participation)). Then, AHP is used to calculate the relative weight of each factor. Finally, by using FLT, the output value of each factor is calculated to find out the best scenarios and influencing factors for the scenario. The result shows that green facilities are the most important dimension, followed by community participation and ecological facilities. Among 45 different scenarios for the model, the best is to consider green facilities and ecological facilities with community participation. The important factors in the best scenario include photovoltaic power generation, planting/vegetation, energy-saving equipment, green building materials, appropriate norms, rainwater collection/water recycling, subsidies, and green roof. The proposed model is validated with residential houses in Conghua District, Guangzhou city, China. Considering the dimensions and factors of the best scenario, the proposed DAFuzzy model proves that a low-carbon and eco-friendly development requires support with appropriate policies and a large investment. The research result suggests that building a low-carbon and eco-friendly house needs the support of the government and people's understanding and participation in eco-friendly development. [ABSTRACT FROM AUTHOR]

Software developers need information for deciding the optimal time for software release with improved software reliability. However, it is not easy for them to decide when and how to release newly developed software to the market. For a decision, the reliability and test costs of the software need to be balanced carefully for avoiding unnecessary confusion and users' complaints. To address this need, related research has been carried out to propose an appropriate tool for such decisions. In many studies, software reliability growth models (SRGMs) were applied using the concept of confidence intervals to estimate the reliability of software. Confidence intervals were calculated on the basis of the assumption of a normal distribution showing the symmetrical occurrence of data with the mean as a center. However, the reliability data of software do not always have such symmetry for assuming the normal distribution. Therefore, it is necessary to propose a method for overcoming the mean value randomness that causes asymmetry in the related data. In previous studies, estimating variance and mean of errors of software was not considered, which led to the unreliable estimation of the confidence intervals of the mean value for decision making. Previous studies also lacked practicability in applications due to statistics from the asymmetrical data distribution. As a result, software developers could not effectively evaluate the possible risk related to the software release time. To improve the estimation, we employ the inflection S-shape model to propose the SRGM on the basis of confidence intervals assumed to come from the normal distribution. The proposed model allows determining the optimal time for software release with the consideration of its potential risk. For efficient determination, the architecture and user interface of the computation system are also proposed. [ABSTRACT FROM AUTHOR]

This Special Issue on "Selected Papers from IEEE ICASI 2018" includes excellent papers presented at the IEEE ICASI 2018 regarding the "applied system innovation" topic. Mechanical engineering and design innovations are both academic and practical engineering fields, which involve systematic technological materialization through scientific principles and engineering designs. Technological innovations in mechanical engineering include IT-based intelligent mechanical systems, mechanics and design innovations, and applied materials in nanosciences and nanotechnology. The aim is to encourage the attendees at the IEEE ICASI 2018 to publish their experimental and theoretical research relating to applied system innovation. [ABSTRACT FROM AUTHOR]

In this study, we prepared low-density ZnO micron rods (MRs) on ITO/PEN substrate by hydrothermal method, and used the scraper to fill the ZnO nanoparticles into the micron rods to prepare ZnO composite structure as the photo-electrode of dye sensitized solar cells (DSSCs). The nanostructures and photo-electrodes were investigated by field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), incident photon conversion efficiency (IPCE) and I-V characteristics analyses. In the results of FE-SEM, they show that the average length of the ZnO MRs and the thickness of ZnO film are 14 and 33.1 μm, respectively. EIS analyses show that there is a minimal R and the longest electron lifetime of DSSCs with the ZnO composite structure, which means less recombination of the electrons in the ZnO composite structure. The results of IPCE indicate that the photo-electrode of ZnO composite structure exhibits the best quantum efficiency about 81.7%. It may be due to ZnO MRs play as a light scattering layer resulting in the increase of path length for the incident light, thereby increasing the collision probability between the incident light and the ZnO nanoparticles. In addition, we also compared the I-V characteristics of three different photo-electrodes with ZnO NPs, ZnO NPs pressed 418.8 kg/cm and ZnO composite structure. The best structure is ZnO composite structure, and it has the best current density (J = 10.59 mA/cm) and overall conversion efficiency (η = 3.46%) of dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

We demonstrate that heterojunction photovoltaics based on hydrothermal-grown InS on p-Si were fabricated and characterized in the paper. An n-type InS nanoflake-based film with unique 'cross-linked network' structure was grown on the prepared p-type silicon substrate. It was found that the bandgap energy of such InS film is 2.5 eV by optical absorption spectra. This unique nanostructure significantly enhances the surface area of the InS films, leading to obtain lower reflectance spectra as the thickness of InS film was increased. Additionally, such a nanostructure resulted in a closer spacing between the cross-linked InS nanostructures and formed more direct conduction paths for electron transportation. Thus, the short-circuit current density ( Jsc) was effectively improved by using a suitable thickness of InS. The power conversion efficiency (PCE, η) of the AZO/InS/textured p-Si heterojunction solar cell with 100-nm-thick InS film was 2.39%. [ABSTRACT FROM AUTHOR]

In this study, dye-sensitized solar cells (DSSCs) were fabricated using nanocrystalline titanium dioxide (TiO 2) nanoparticles as photoanode. Photoanode thin films were prepared by doctor blading method with 420 kg/cm 2 of mechanical compression process and heat treatment in the air at 500°C for 30 min. The optimal thickness of the TiO 2 NP photoanode is 26.6 μm with an efficiency of 9.01% under AM 1.5G illumination at 100 mW/cm 2. The efficiency is around two times higher than that of conventional DSSCs with an uncompressed photoanode. The open-circuit voltage of DSSCs decreases as the thickness increases. One DSSC (sample D) has the highest conversion efficiency while it has the maximum short-circuit current density. The results indicate that the short-circuit current density is a compromise between two conflict factors: enlargement of the surface area by increasing photoanode thickness and extension of the electron diffusion length to the electrode as the thickness increases. [ABSTRACT FROM AUTHOR]

The preparation and characterization of heterojunction solar cell with ZnS nanocrystals synthesized by chemical bath deposition method were studied in this work. The ZnS nanocrystals were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Lower reflectance spectra were found as the annealing temperature of ZnS film increased on the textured p-Si substrate. It was found that the power conversion efficiency (PCE) of the AZO/ZnS/textured p-Si heterojunction solar cell with an annealing temperature of 250°C was η = 3.66%. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the fabrication of ZnO-based thin-film transistors (TFTs) on flexible substrates (polyethylene terephthalate) through radio-frequency sputtering and low-temperature procedure. The device structure belongs to bottom-gate type TFTs where ZnO and HfO2 are used as channel and gate dielectric layer, respectively. XRD results show that the ZnO channel layers are hexagonal wurtzite structure with (002) orientation. The properties of the fabricated devices are also characterized within several environmental and physics conditions. It can be found that the flexible TFT device is with a low operating voltage and high current ON/ OFF ratio; the gate leakage current and transparency are found to be \sim12~nA and 75%, respectively. The gate leakage current (IG), drain-source current (IDS), ON/OFF current ratio (I\rm{ON/OFF}), threshold voltage (Vth), and field-effect mobility (\mu\rm{FE}) are measured under different bending modes. [ABSTRACT FROM PUBLISHER]

Herein transparent Zn1-xFexO nanocrystalline films have been prepared on glass substrates by sol-gel method followed by rapid thermal annealing treatment. The effecs of Fe doping on the microstructure, transmittance and magnetism of Zn1-xFexO nanocrystalline films are investigated. The x-ray diffraction patterns of all compositions show the same wurtzite hexagonal structure with the space group P63/mc. FE-SEM images show uniform spherical grains of all Zn1-xFexO nanocrystalline films in which the grain size decreases progressively from 38.85 nm (x = 0.00) to 15.35 nm (x = 0.04). Red shift of the absorption edges is obtained from the optical transmittance spectra from 372 nm of undoped ZnO film to 367 nm of Zn0.96Fe0.04O film. The corresponding wide band gap energy of undoped ZnO film is 3.2986 eV which decreases slightly by 0.0191 eV of Zn0.96Fe0.04O film. The saturation magnetization increases with the increase of Fe concentration. All Fe-doped ZnO films exhibit feromagnetic hysteresis curves which can be well fitted by the law of approaching to saturation with the formula, M = MS(1 − a/Hm). [ABSTRACT FROM PUBLISHER]

In this study, a metal-oxide-semiconductor (MOS) structure with NiSi2nanocrystals embedded in a high-κ oxide layer, HfO2, was fabricated. The vertical transport properties have been studied by the temperature-dependent current-gate voltage (I-Vg) measurement. The temperature-dependent I-Vgcurves show another threshold voltage of between about −3.7 and −3.2 V in the forward and backward sweeps of the low temperature region, from 30 K to 150 K. We attribute this abnormal threshold voltage to charge redistribution due to the resistant phase change of the NiSi2nanocrystals. [ABSTRACT FROM PUBLISHER]

In this study, the organic material 2-4-tert-butylphenyl-5- 4-biphenylyl-1,3,4-oxadiazole (PBD) is used as a hole blocking layer (HBL) and is inserted between 4, 4′-bis (2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) and tris-(8-hydroxyquinoline) aluminum (Alq3) layers to avoid color mixing in devices. The configuration of device was as follows; indium tin oxide (ITO)/N,N′-bis-(1-naphthyl) –N,N′-diphenyl-1,1′- biphenyl-4,4-diamine (NPB)/DPVBi /PBD (d nm)/ Alq3/LiF/Al. The difference between the highest occupied molecular orbital (HOMO) of PBD and that of DPVBi, and the difference between the lowest unoccupied molecular orbital (LUMO) of PBD and that of Alq3 are used to block the carriers. Changing the thickness of PBD layer and the operating voltages in devices produced a different recombination zone for the shift of carriers, causing emission of different colors. Accordingly, devices can emit two colors—blue at a low operating voltage and green at a high operating voltage. [ABSTRACT FROM PUBLISHER]