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Crystal facet engineering induced anisotropic transport of charge carriers in a perovskite
摘要： Precise control of crystal orientations and macroscopic morphology of a perovskite crystal is crucial for various optoelectronic applications relying on charge carrier transport tuning along exposed crystal facets. Here, taking methylammonium lead bromide (CH3NH3PbBr3) as an example, and employing a novel crystal facet engineering method, we successfully construct two kinds of perovskite crystals with exposed {001} and {110} facets. We find that the free carriers’ photoluminescence lifetime on the {001} facets can be 3 times longer than that on {110} facets. The related mechanisms are investigated via fluorescence lifetime imaging microscopy and in situ transmission electron microscopy. These indicate that the different trap state density of exposed facets and crystal structure changing of CH3NH3PbBr3 under light and electron beam irradiation lead to the differences in carrier transport along different facets. By distinguishing the charge carrier transport on different CH3NH3PbBr3 exposed facets, micro-photodetectors have been constructed. A device fabricated with the {001} exposed facets exhibited two orders of magnitude higher photocurrent and half as much dark current as a {110} facet-based device. Thus, the crystal facet engineering of perovskites can be widely adopted for understanding physical/chemical properties of perovskite crystals and provides great potential for novel perovskite optoelectronic device applications.
关键词： crystal facet engineering,charge carrier transport,optoelectronic applications,photodetectors,perovskite
更新于2025-09-09 09:28:46
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Epitaxial ferroelectric oxide thin films for optical applications
摘要： Ferroelectrics are non-centrosymmetric crystalline materials that possess a spontaneous polarization that can be switched by an electric field. The electric-field-dependent optical response of these materials makes them important for optical devices, such as modulators or beam deflectors. In the inexorable drive to miniaturization, the concept of integrated thin film optical devices has led to the incorporation of ferroelectric thin films on single-crystal substrates. These structures have appealing electro-optic modulation characteristics, interesting strain-dependent bandgaps and refractive index, as well as promising possibilities for solar harvesting. Here, we review the work on epitaxial ferroelectric (FE) films for optical applications. We first show that FE thin film materials are attractive for integrated electro-optic modulators and then show that epitaxial strain can be used to enhance the FE and optical functionality of films. Next, we describe some of the photovoltaic functionality of FE thin film materials’ systems and conclude the review by highlighting some thin-film devices that exploit the aforementioned optical effects.
关键词： epitaxial strain,electro-optic modulators,thin films,photovoltaic,optical applications,ferroelectric
更新于2025-09-09 09:28:46
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Near <scp>IR</scp> Photochemistry for Biology: Exploiting the Optical Window of Tissue
摘要： Photoactive molecules enable much of modern biology and biochemistry – a vast library of fluorescent chromophores is used to track and label cellular structures and macromolecules. However, photochemistry is better-known to the synthetic or physical organic chemist as a “light switch” that turns on unusual excited-state reactivity, isomerization, or dynamic adjustment of structure. This review details a rapidly growing approach to bio-photochemistry that uses low-energy near-IR wavelengths not only for imaging, but for close spatial control over chemical switching events in biosystems. Emphasis is placed on topics of biomedical interest: release of gaseous biological messengers, uncaging of drugs, nano-therapeutics, and modification of biomaterials.
关键词： drug uncaging,bio-photochemistry,nano-therapeutics,biomaterials modification,optical window of tissue,biomedical applications,gasotransmitters,Near IR photochemistry
更新于2025-09-09 09:28:46
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On the Higher-Order Approximations for Efficient Computational Electromagnetics of the Surface Integral Equation
摘要： In this paper, we propose an ef?cient procedure to obtain loop and star basis functions useful to the surface integral equation. They are of any order, for 3-D curved surfaces, and they keep the solenoidal/nonsolenoidal splitting, improving the performance for low frequencies (near ?eld). These bases, introduced in a former work and applied to the electric ?eld integral equation (EFIE), herein are used in both the magnetic ?eld integral equation (MFIE) and the combined ?eld integral equation (CFIE) providing a good performance even at the low-frequency regime. For addressing the low-frequency performance, scale factors and normalization of the basis are applied to EFIE, MFIE, and CFIE formulations.
关键词： low-frequency applications,loop/star splitting,Higher order basis functions
更新于2025-09-09 09:28:46
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Novel Method of Determining Vehicle Cartesian Location Using Dual Active Optical Beacons and a Rotating Photosensor
摘要： A novel system for sensing the location of a vehicle in a region of interest has been implemented; it has applications for mobile ground or aerial vehicle navigation (or positioning) in environments where other types of environmental localization are absent (e.g., lack of radio or GPS signals). The system uses photodetection of encoded laser-beam pulses emitted from a pair of beacons to gather information and perform localization calculations with reasonable accuracy. Testing of the realized system has shown consistent results that are in line with predictions from the previous model simulations. The approach of using dual angle-encoded beacons is shown to be a valid methodology for determining relative location and orientation in a sterile environment. Future optimizations would increase the pulse rates of the lasers, the rotational speed of the beacons, and use mirrors or prisms to replace the rotating detector with a stationary one.
关键词： localization,photodetector,Sensor applications,beacon,laser,sensor applications
更新于2025-09-04 15:30:14
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Thermal management and characterization of high-power wide-bandgap semiconductor electronic and photonic devices in automotive applications
摘要： GaN-based high-power wide-bandgap semiconductor electronics and photonics have been considered as promising candidates to replace conventional devices for automotive applications due to high energy conversion efficiency, ruggedness, and superior transient performance. However, performance and reliability are detrimentally impacted by significant heat generation in the device active area. Therefore, thermal management plays a critical role in the development of GaN-based high-power electronic and photonic devices. This paper presents a comprehensive review of the thermal management strategies for GaN-based lateral power/RF transistors and light-emitting diodes (LEDs) reported by researchers in both industry and academia. The review is divided into three parts: (1) a survey of thermal metrology techniques, including infrared thermography, Raman thermometry, and thermoreflectance thermal imaging, that have been applied to study GaN electronics and photonics, (2) practical thermal management solutions for GaN power electronics, and (3) packaging techniques and cooling systems for GaN LEDs used in automotive lighting applications.
关键词： semiconductor,Raman thermometry,infrared thermography,high-power,automotive applications,LEDs,thermoreflectance thermal imaging,GaN,thermal management,wide-bandgap
更新于2025-09-04 15:30:14
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Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays
摘要： A MATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array.
关键词： three-dimensional sensing,arrays,three-dimensional image acquisition,three-dimensional image processing,thin film devices and applications,optical sensing and sensors
更新于2025-09-04 15:30:14
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[EAI/Springer Innovations in Communication and Computing] Mobile Solutions and Their Usefulness in Everyday Life || Smartphone Sensing Technologies for Tailored Parkinson’s Disease Diagnosis and Monitoring
摘要： Parkinsonian syndromes are a heterogeneous entity of movement disorders, with various described subtypes. This systematic review aimed to examine the available literature on smartphone applications for assessment of Parkinson’s disease motor and nonmotor symptoms and signs. Papers published from 2013 to 2017, listed in two electronic databases—IEEE Xplore and PubMed—were searched, to identify the works related with smartphone use for PD patients’ diagnosis and monitoring. Full-text articles were analyzed to evaluate the quality of the reported methods and results, considering the validity, reliability, and sensitivity of the techniques used in the measurements as well as the Grading of Recommendations Assessment, Development and Evaluation guideline. The data from 26 full-text articles suggest that many and relevant data can be collected automatically and accurately via mobile phone. Inertial measurement units as well as capacitive, force/pressure, acoustic sensors were used for the development of smartphone-based tools to improve assessment and monitor symptoms and signs of Parkinson’s disease. Smartphone-based information on upper limbs tremor, gait, posture, balance, activities, and speech may improve quality of healthcare services for Parkinson’s disease patients and their quality of life.
关键词： diagnosis,Parkinson’s disease,motor symptoms,nonmotor symptoms,smartphone applications,monitoring
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Potential of solar central tower systems for thermal applications in the production chain of copper by pyrometallurgical route
摘要： Copper is an indispensable input element in most economic sectors. However, its production chain has significant and adverse consequences on the environment. Through pyrometallurgical route it is estimated that each kilogram of refined copper consumes 33 MJ and generates a footprint of 3.3 kg of CO2. Primary production projections for 2019 amount to 26,500 kT, of which 79% will be by pyrometallurgical route. It is a responsibility of the industry to makes the process more environmental friendly. This can be done replacing the current energy matrix by the use of renewable energy. In this first and preliminary work we are evaluating the technical potential to integrate Central Tower Plants (CTP) into the smelting stage as a solar energy source. According to the mineral books and the irradiation maps, almost 20% of the current production can be match with these solar concentration systems because of the irradiance levels available where the metallurgical plants are located. The incorporation of a CTP in the world largest copper metallurgical facility to substitute the current fossil fuel energy supply could demand a capacity of 68 MWt. This last consideration obeys to the weighted average of the specific energy consumption gave by the Chilean Copper Commission COCHILCO. However, the results of this work indicate that the behavior of this change in the operative parameters could reduce the 68 MWt almost in a half.
关键词： solar central tower systems,copper production,renewable energy,pyrometallurgical route,thermal applications
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore, India (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Differential Pressure Sensor Using Silicon on Insulator Back to Back Cantilever Structure
摘要： In our day to day life differential pressure sensor can be used in much application. This type of pressure sensors are used for measuring the difference between two different pressure levels. Mostly bulk micro machined fabrication tool is used for fabrication process. Hence these type sensors have low cost and reliable than normal conventional sensor. This sensor is designed mainly to compare both the pressure below and above the liquid and flow rates and measures changes in pressure across restriction. The output differential pressure sensor varies with respect to the change in pressure level at up (or) down cantilever beam. When the pressure value at bottom side is high, when the membrane deflect towards forward direction (i.e.) moves upward. when the pressure value at which the bottom side is lower than the membrane deflects to backward direction (moves downward). This design is mainly used in domestic and industrial application.
关键词： Agriculture Applications,MEMS,Humidity Sensor,Temperature Sensor,Finite Element Method (FEM),micro-Cantilever
更新于2025-09-04 15:30:14