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Segregation-free bromine-doped perovskite solar cells for IoT applications
摘要： Perovskite solar cells have attracted much attention as next-generation solar cells because of their high e?ciency and low fabrication costs. Moreover, perovskite solar cells are a promising candidate for indoor energy harvesting. We investigated the e?ect of bandgap tuning on the characteristics of triple cation-based perovskite solar cells under ?uorescent lamp illumination. According to the current density–voltage curves, perovskite solar cells with a wider bandgap than the conventional one exhibited improved open-circuit voltage without sacri?cing short-circuit current density under ?uorescent lamp illumination. Moreover, the wider bandgap perovskite ?lms including a large amount of bromine in the composition did not show phase segregation, which can degrade the photovoltaic performance of perovskite solar cells, after ?uorescent lamp illumination. Our results demonstrate the facile strategy to improve the performance of perovskite solar cells under ambient lighting and great potential of perovskite solar cells for indoor applications such as power sources for the internet of things.
关键词： indoor energy harvesting,perovskite solar cells,IoT applications,bromine-doped,bandgap tuning
更新于2025-09-16 10:30:52
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Light-controlled two-dimensional TiO <sub/>2</sub> plate micromotors
摘要： In this work, UV light-controlled two-dimensional (2D) TiO2 plate micromotors are demonstrated for the first time. The 2D TiO2 micromotors are produced by the well-known anodic oxidation method in combination with a cracking and separation process. When the motor is placed in H2O2 aqueous solution under UV irradiation, oxygen bubbles are generated in the holes of the TiO2 membrane. The 2D micromotor thus moves upon O2 bubbles under its own weight. In contrast to bubble-propelled micromotors, which require an addition of surfactants to chemical fuels, the 2D micromotor is capable of moving in aqueous H2O2 solution without surfactants. Moreover, speed of the 2D TiO2 micromotor can be controlled by the intensity of the UV light. Such surfactant-free micromotors and their facile fabrication hold considerable promise for diverse practical applications in the biomedical and energy fields, for example, and in new materials.
关键词： two-dimensional TiO2 plate micromotors,UV light-controlled,anodic oxidation method,energy fields,surfactant-free,biomedical applications
更新于2025-09-16 10:30:52
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Measurement of Polarization Transient Effects Caused by Mechanical Stress on Optical Fiber
摘要： The paper deals with measurement of polarization transient effects in single mode optical fiber caused by mechanical stress generated by fiber stretcher. An unexpected event like digging near the buried fiber route can be monitored and evaluated. We performed an experimental verification using polarimeter and balanced photodetector for state of polarization analysis. The results show that the analysis based on polarization splitter and a balanced detector gives sufficient and comparable results to the polarimeter. In addition, it is a cost-effective solution and with the FFT it is possible to perform a quick evaluation of the event frequency.
关键词： Optical fiber polarization,Optical fiber applications,Optical fiber sensors
更新于2025-09-16 10:30:52
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Complementary metal oxide semiconductor (CMOS) compatible gallium arsenide metal-semiconductor-metal photodetectors (GaAs MSMPDs) on silicon using ultra-thin germanium buffer layer for visible photonic applications
摘要： The monolithic integration of III–V materials on silicon appears as the most promising, cost-effective, and versatile method for next-generation optoelectronic devices. Here, we report on GaAs metal-semiconductor-metal photodetectors integrated on an Si substrate by metal-organic chemical vapor deposition. The device architecture is based on a GaAs active layer grown on Si via ultrathin, low-temperature Ge buffer layers. The Ge-on-Si acts as a “virtual” substrate to reduce the overall structural defects in the GaAs device layers. The metal-semiconductor junction characteristics were optimized to effectively suppress the dark current and passivate the interface defects. This was achieved through the insertion of an ultrathin Al2O3 interlayer at the metal/GaAs interface. The results show that a Schottky barrier height of 0.62 eV and 0.8 eV for electrons and holes, respectively, can be achieved. Circular devices with diameters ranging from 30 to 140 μm were fabricated. The measured room temperature dark current is ～48 nA for an applied reverse bias of 1.0 V and a device diameter of 30 μm. Additionally, the GaAs metal-semiconductor-metal structure exhibited a remarkable photoresponsivity and detectivity values of (0.54 ± 0.15) A/W and ～4.6 × 1010 cm Hz1/2 W?1 at 5 V reverse bias, 850 nm, respectively. The proposed method offers great potential for the monolithic integration of GaAs on an Si platform. Furthermore, this technique can be extended to other III–V materials and lattice mismatched systems for high-performance multiple band optoelectronics.
关键词： gallium arsenide,visible photonic applications,metal-semiconductor-metal photodetectors,germanium buffer layer,CMOS
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Electrical Engineering Research & Practice (ICEERP) - SYDNEY, Australia (2019.11.24-2019.11.28)] 2019 International Conference on Electrical Engineering Research & Practice (ICEERP) - Photovoltaic-Based Distribution Generation System Integration Effects on the Power Quality Issues on Electrical Distribution Network
摘要： Rapid advance of location acquisition technologies boosts the generation of trajectory data, which track the traces of moving objects. A trajectory is typically represented by a sequence of timestamped geographical locations. A wide spectrum of applications can benefit from the trajectory data mining. Bringing unprecedented opportunities, large-scale trajectory data also pose great challenges. In this paper, we survey various applications of trajectory data mining, e.g., path discovery, location prediction, movement behavior analysis, and so on. Furthermore, this paper reviews an extensive collection of existing trajectory data mining techniques and discusses them in a framework of trajectory data mining. This framework and the survey can be used as a guideline for designing future trajectory data mining solutions.
关键词： data mining techniques,Trajectory data mining,big data applications
更新于2025-09-16 10:30:52
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Electronic and optical properties of two propounded compound in photovoltaic applications, CsPbI3 and CH3NH3PbI3: By DFT
摘要： Halide perovskite compounds are the serious contenders for conventional materials used in photovoltaic devices that will provide a bright future for solar cell industry. Therefore, preparing a comprehensive insight about their properties is necessary. In this regard, the electronic and optical studies of two important perovskite compound CsPbI3 and CH3NH3PbI3 in the cubic phase are performed by ?rst- principle method in Density Function Theory (DFT), using several approximations namely GGA, t-mbj and other types of t-mbj approximation with the tuned coef?cient including k-mbj and new mbj approximations. In addition to utilizing di?erent approximations, the e?ect of spin orbit coupling which is critical in these compounds, is evaluated in all of them to obtain realistic results. The band gaps calculated within new mbj approximation through spin orbit coupling are 1.34 eV and 1.49 eV for CsPbI3 and CH3NH3PbI3, respectively that unlike other DFT-based electronic calculations are in agreement with experimental results. Values of estimated e?ective masses of carriers represent lighter carriers for CH3NH3PbI3 in comparison to CsPbI3. Optical calculations of frequency dependent dielectric function con?rm non isotropic property in organic- inorganic perovskite CH3NH3PbI3 and estimate value of static refraction index equal to 2.47 which is in agreement with experimental measurements.
关键词： DFT,Optical properties,CsPbI3,CH3NH3PbI3,Photovoltaic applications
更新于2025-09-16 10:30:52
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Efficient coupling of light from dielectric to HIMI plasmonic waveguide
摘要： This is the ?rst report on the investigation of a hybrid plasmonic tapered coupler injecting light ef?ciently from conventional dielectric waveguide to a hybrid insulator–metal–insulator (HIMI) plasmonic waveguide. The proposed structure gives high transmission ef?ciency and suppresses the re?ection losses signi?cantly. With this tapered coupling mechanism, maximum transmittance and return loss of 98% and 26 dB have been observed, respectively. The coupler also offers very good propagation length (274 μm) along with minimal mode propagation losses (0.016 dB/μm). Apart from that, it offers decent con?nement of light in low dielectric regions up to 32%. The proposed structure is designed in an ultra-short tapered length of 1.0 μm, and the entire structure occupies a footprint area of 1.4 × 2.4 μm2. Proposed hybrid waveguide coupler could be useful for several chip scale applications.
关键词： chip scale applications,light confinement,hybrid plasmonic tapered coupler,propagation length,mode propagation losses,reflection losses,HIMI plasmonic waveguide,transmission efficiency
更新于2025-09-16 10:30:52
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Dual-band and ultra-broadband photonic spin-orbit interaction for electromagnetic shaping based on single-layer silicon metasurfaces
摘要： Achieving electromagnetic wave scattering manipulation in the multispectral and broad operation band has been a long pursuit in stealth applications. Here, we present an approach by using single-layer metasurfaces composed of space-variant amorphous silicon ridges tiled on a metallic mirror to generate high-efficiency dual-band and ultra-wideband photonic spin-orbit interaction and geometric phase. Two scattering engineered metasurfaces have been designed to reduce specular reflection; the first one can suppress both specular reflectances at 1.05–1.08 μm and 5–12 μm below 10%. The second one is designed for an ultra-broadband of 4.6–14 μm, which is actually implemented by cleverly connecting two bands of 4.6–6.1 μm and 6.1–14 μm. Furthermore, the presented structures exhibit low thermal emission at the same time due to the low absorption loss of silicon in the infrared spectrum, which can be regarded as an achievement of laser–infrared compatible camouflage. We believe the proposed strategy may open a new route to implement multispectral electromagnetic modulation and multiphysical engineering applications.
关键词： photonic spin-orbit interaction,stealth applications,geometric phase,metasurfaces,electromagnetic shaping
更新于2025-09-16 10:30:52
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - RF and Network Signature-based Machine Learning on Detection of Wireless Controlled Drone
摘要： A technique to estimate tropical cyclone (TC) current intensity based on geostationary satellite infrared window (IRW) and water vapor (WV) imagery is explored in this paper. First, to combine the advantages of the IRW imagery and the WV minus IRW (WV-IRW) imagery, a WV-IRW-to-IRW ratio (WIRa)-based indicator is proposed. This indicator not only can display the inner-core convection’s symmetrization level and vigor but also is able to screen out thin cirrus, stratospheric WV anomaly, and overshooting tops from average deep convection. It is highly correlated with the best track minimum sea-level pressure and thus used to estimate the western North Paci?c TC current intensity. Detailed analyses have demonstrated that the WIRa-based indicator can further improve the estimation of TC current intensity alongside the existing algorithms. The WIRa-based indicator is designed based on the hypothesis that “overshooting top is more useful for forecasting than initial estimation,” and the satisfying results of the WIRa-based method perhaps provide indirect evidence to support this hypothesis in turn.
关键词： remote sensing,satellite applications,tropical cyclone,Meteorology
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - AlGaAs/InGaP MBE-grown heterostructures for 1.73eV Solar Cells With 18.7% Efficiency
摘要： In this paper, the energy recovery in microstrip passive circuits from the power losses into heat is studied. For this purpose, a thermoelectric generator (TEG) based on the Seebeck effect principle is used, which converts part of the power dissipated into heat to dc electrical power. A solution integrating the TEG with the microstrip circuit is proposed, and design guidelines in order to optimize the recovered power keeping a good isolation between the RF signal and the TEG system are provided. As will be shown, under moderate applied signal powers of just 1–5 W, the levels of recovered power in microstrip passive circuits can be notable. As a demonstrator circuit, an integration device formed by an embedded microstrip bandpass filter for WiMAX applications and a TEG is designed, fabricated, and characterized (thermal and electrically). Different scenarios are considered, depending on frequency and thermal loads. For an applied in-band CW input signal power of 2 W at 3.48 GHz, a recovered power of around 250 μW has been continuously supplied to the electrical load. Several aspects, such as efficiency and future improvements, are also discussed.
关键词： power applications,Average power handling capability (APHC),microwave devices,planar circuits,energy recovery,electro-thermal analysis,energy harvesting
更新于2025-09-16 10:30:52