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Unique ion diffusion properties in lead-free halide double perovskites: A first-principles study
摘要： Pb-free halide double perovskites (HDPs) are proposed as potential candidates for various optoelectronic applications to replace the mainstream hybrid organic-inorganic halide perovskites, e.g., CH3NH3PbI3. While it is known that ion di?usion is a critical problem to a?ect the structural and electronic stability of CH3NH3PbI3, the mechanism of ion di?usions in HDPs is still unclear and highly desired to be revealed. In this study, taking Cs2AgInX6 (X = Cl, Br) HDPs as prototypes, for the ?rst time we suggest that the fast ion di?usion of the dominant defects may play an important role in the performance stability of HDPs. Importantly, we ?nd that the Agi+ di?usion in a multi-ion concerted fashion has a much faster di?usion rate, compared to the VAg? and VX? di?usion in a single-ion fashion. It is revealed that HDPs exhibit quite di?erent di?usion properties from CH3NH3PbI3. Furthermore, we demonstrate that the di?usion rate of Agi+ in HDPs can be e?ectively suppressed by applying an epitaxial strain, which opens a promising way to enhance the performance stability of perovskite materials for various device applications.
关键词： Lead-free halide double perovskites,Ion di?usion,Performance stability,ab initio calculations,Solar cells
更新于2025-09-04 15:30:14
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High-Performance Transparent and Flexible Electrodes Made by Flash-Light Sintering of Gold Nanoparticles
摘要： Metallic nanowire-based transparent electrodes (TEs) are potential alternatives to indium tin oxide (ITO). To achieve a high performance [sheet resistance (Rs) <100 Ω/sq, transmittance (T%) > 90%], the nanowires must have a high length-to-diameter (L/D) ratio to minimize the number of wire-to-wire junctions. Attempts to produce TEs with gold nanowires have been made, and the results reveal difficulties in achieving the requirements. A successful strategy involves creating templated gold nanonetworks through multiple procedures. Here, we present a simple and efficient method that uses flash-light sintering of a gold nanonetwork film into gold TEs (Rs: 82.9 Ω/sq, T%: 91.79%) on a thin polycarbonate film (25 μm). The produced gold TEs have excellent mechanical, electrical, optical and chemical stabilities. Mechanisms of the formation of gold nano-networks and the effect of flash-light have been analyzed. Our findings provide a scalable process for producing transparent and flexible gold electrodes with a total processing time of less than 8 min without the use of heating, vacuum processing, organic chemicals and without any material loss. This is possible because all the gold nanoparticles have been aggregated and filtrated on the filter membranes. The area density of gold is 0.094 g/m2 leading low material costs, which is very competitive with the price of commercial TEs.
关键词： flexible electrode,high performance,transparent electrode,gold nanoparticles,flash-light sintering
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Intelligent Transportation Systems (ITSC) - Maui, HI, USA (2018.11.4-2018.11.7)] 2018 21st International Conference on Intelligent Transportation Systems (ITSC) - Automotive LiDAR performance verification in fog and rain
摘要： This article focuses on testing and investigating further development needs for LiDARs in self-driving cars in adverse weather. The article compares two different LiDARs (Ibeo Lux and Velodyne PUCK), which both use the 905 nm wavelengths, which are used in more than 95 % of currently available LiDARs. The performance was tested and estimated in stabilized fog conditions at Cerema fog chamber facilities. This provides a good basis for repeating the same validation procedure multiple times and ensuring the right development decisions. However, performance of the LiDARs suffers when the weather conditions become adverse and visibility range decreases. A 50 % reduction in target detection performance was observed over the exhaustive tests. Therefore, changing to higher wavelengths (1550 nm) was considered using redesigned “pre-prototype LiDAR”. The preliminary results indicate that there is no reason to not use 1550 nm wavelength, which due to eye safety regulations gives an opportunity to use 20 times more power compared to the traditional 905 nm. In order to clarify the expected benefits, additional feasibility studies are still needed.
关键词： self-driving cars,LiDAR,sensor performance,1550 nm,905 nm,adverse weather,rain,fog
更新于2025-09-04 15:30:14
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Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors
摘要： Metal-oxide based thin-film transistors (oxide-TFTs) are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.
关键词： thin-film transistors,oxygen annealing,HfIZO,photo-induced stability,device performance
更新于2025-09-04 15:30:14
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Near infrared estimation of concentration of ginsenosides in Asian ginseng
摘要： In this study, the feasibility of near infrared reflectance spectroscopy for the quality evaluation of the main bioactive compounds, ginsenosides, in Panax ginseng was examined. Second derivative NIR spectra of standard reagents of ginsenoside Rg1, Re, Rb1, Rc, Rb2 and Rd were used for analysis. Characteristic bands were observed at around 5250 cm?1 in the spectra of ginsenoside Rg1 group (including Rg1 and Re); however, this was not to be observed on the spectra of ginsenoside Rb1 group (including Rb1, Rc, Rb2 and Rd). PLS regression models were constructed of air-dry ginseng powder samples and ginsenoside content in ginsengs was determined by HPLC methods. The calibration models covered various types of ginseng (white ginseng, red ginseng and bleached ginseng) from various cultivated areas (Japan, China and Korea) and were well established for each kind of ginsenoside. It was shown that NIR spectroscopy can be used for the accurate prediction of ginsenoside.
关键词： high-performance liquid chromatography,white ginseng,Panax ginseng,ginsenoside contents,red ginseng
更新于2025-09-04 15:30:14
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A Facile Green Approach for Synthesis of Selenium Nanowires with Visible Light Photocatalytic Properties
摘要： In this work, high purity trigonal selenium (t-Se) nanowires were synthesized through a simple one-step solvothermal process at 50 °C. Sodium formaldehyde sulfoxylate (SFS) was used as a reducing agent. To our knowledge, this is the first time that SFS was used as the reducing agent for synthesis of Se nanostructures. In this method, Se nanowires were obtained at lower temperature, shorter period of reaction time and without using complex equipment. The experimental parameters, such as reaction duration, temperature and amount of surfactant, were investigated. The as-prepared Se nanowires have a diameter of about 100–200 nm and length of up to 10 μm. A “Solid–Solution–Solid” growth mechanism was proposed. In the presence of H2O2, the Se nanowires showed good catalytic performance, where over 99% of methylene blue (MB) was degraded in 3.0 h. Results from this study demonstrated that the Se nanowires exhibit a promising application for photodegradation.
关键词： Synthesis,Photocatalytic Performance,Selenium,Nanowires
更新于2025-09-04 15:30:14
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An Optimized Telecommunication System Topology for Expenditure Minimization and Improved Spectral Utilization Efficiency
摘要： Capital expenditures (CAPEX) and operational expenditure (OPEX) has always been on the high side if transmission networks are not efficiently planned to minimize these costs. The arrays of antenna often sighted on mast/tower around often post a major risk to the industry as CAPEX increases with increased hardware and signal processing cost. This paper explores the use of point to multipoint (PMP) method of backhauling traffic for cognitive radio network as veritable alternative to existing transmission Point to Point (PTP) Topology in other to minimize the CAPEX and OPEX as well as improve spectra utilization efficiency. The work is focused on small cell deployment for more data penetration in a redundant setup to improve system availability. In the work, the Dijkstra Algorithm for Shortest route analysis was used to prove the advantage of Point to multi point approach in the optimal path planning in a transmission network taking cognizance of path costs as the capital expenditure, path loss, latency, throughput, frequency channel allocation. Furthermore, a spectrum utilization problem was defined, formulated and analyzed. Solution of this model was validated using a simulated setup on a section of Ikorodu (6°35”.37 N and 3°31”.53.99 E) transmission axis. Results obtained from the analysis show that our model of PMP method of transmitting/backhauling is more capable of improving the spectral efficiency of a wireless telecommunication network and outperforms the PTP topology on all network measures influencing capital and operational expenditures.
关键词： Point to multi-point,Shortest route,Spectrum efficiency,Network performance measures,Point to point
更新于2025-09-04 15:30:14
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Angle dependence of synthesized BiOI prepared by dip coating and its effect on the photovoltaic performance
摘要： A study about the angle effect on the synthesis of BiOI films via modified successive ionic layer adsorption and reaction (SILAR) and its application as p-type semiconductor in solar cell construction have been carried out. By involving the angle inclination on the BiOI synthesis process in this work, it showed the impact on the BiOI film thickness. We found the thicker films contained larger flaky morphology which was displayed by the FESEM image. Also, it exhibited an increase of the Bi-I internal stretching mode (Eg) in the Raman spectra, BiOI peak absorbance in the visible region, and its crystal intensity in the XRD pattern along with the decreasing angle from 90° to 50° while SILAR process was running. Although our BiOI films performed better Jsc compared to previous studies, their photovoltaic parameters decreased slightly upon the reducing angle, which induced larger BiOI growth in the larger flaky cluster.
关键词： angle dependence,dip coating,photovoltaic performance,BiOI,SILAR
更新于2025-09-04 15:30:14
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Latency analysis on W-band hybrid fiber-wireless link using software defined radio in real time
摘要： This paper reports an experimental comparison and analysis of latency for different modulation techniques at different data rates in W-band Radio-over-Fiber (RoF) transmission links. In addition, a software defined radio called GNU-Radio is employed with Universal Software Radio Peripherals (USRP) to generate and retrieve the transmitted signals. Likewise, it is used to test the end to end latency in the W-band RoF link. Our main contribution is achieving a W-Band low-latency wireless fiber link which fits to the key performance indicators of 5G networks.
关键词： Radio over Fiber,W band,Network Performance,Software defined radio
更新于2025-09-04 15:30:14
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Preparation of Nano-SiO2/Al2O3/ZnO-Blended PVDF Cation-Exchange Membranes with Improved Membrane Permselectivity and Oxidation Stability
摘要： Ion exchange membranes are used in practically every industry; however, most of them have defects such as low permeability and poor oxidation resistance. In this paper, cation-exchange membranes were prepared with poly (vinylidene fluoride) (PVDF) blended with nano-SiO2, nano-Al2O3 and nano-ZnO. Sulfonic acid groups were injected into the membrane prepared by styrene grafting and sulfonation. The methods used for characterizing the prepared membranes were Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and electrochemical measurements. Membrane performance, such as the ion exchange capacity (IEC), water uptake (WU), transport number, membrane permselectivity, membrane resistance, functional groups, and morphology were also evaluated. The hydrophilia, IEC, and permselectivity of cation-exchange membranes depended on the nanoparticle content of the membrane matrix. High transport property values were obtained, which increased with increasing nano-SiO2/Al2O3/ZnO weight fractions. Finally, the cation-exchange membranes prepared with 1.5% nano-SiO2, 2.0% nano-Al2O3 or 2.0% nano-ZnO all exhibited excellent membrane properties, including membrane permselectivity (PVDF/2% ZnO-g-PSSA membranes, 94.9%), IEC (PVDF/2% Al2O3-g-PSSA membranes, 2.735 mmol·g?1), and oxidation resistance (PVDF/1.5% SiO2-g-PSSA membranes, 2.33%). They can be used to separate applications in a variety of different areas, such as water treatment, electro-driven separation, heavy metal smelting, or other electrochemical processes.
关键词： cation-exchange membrane,nano-SiO2/Al2O3/ZnO,poly(vinylidene fluoride),membrane performance
更新于2025-09-04 15:30:14