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CsPbBr3 perovskite quantum-dot paper exhibiting a highest 3 dB bandwidth and realizing a flexible white-light system for visible-light communication

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Photonics Research 2021年第12期9卷 2341-2350页

作者： KONTHOUJAM JAMES SINGH XIAOTONG FAN ANNADA SANKAR SADHU CHUN-HO LIN FANG-JYUN LIOU TINGZHU WU YU-JUNG LU JR-HAU HE ZHONG CHEN TOM WU HAO-CHUNG KUO Department of Photonics&Institute of Electro-Optical Engineering College of Electrical and Computer EngineeringNational Yang Ming Chiao Tung UniversityHsinchu 30010Taiwan International Ph.D.Program in Photonics(UST) College of Electrical and Computer EngineeringNational Yang Ming Chiao Tung UniversityHsinchu 30010Taiwan Department of Electronic Science Fujian Engineering Research Center for Solid-State LightingXiamen UniversityXiamen 361005China School of Materials Science and Engineering University of New South WalesSydneyNSW 2052Australia Research Center for Applied Sciences Academia SinicaTaipei 11529Taiwan Department of Materials Science and Engineering City University of Hong KongKowloon TongHong KongChina

We propose a flexible white-light system for high-speed visible-light communication(VLC)applications,which consists of a semipolar blue InGaN/GaN single-quantum-well micro-light-emitting diode(LED)on a flexible substrate pumping green CsPbBr3 perovskite quantum-dot(PQD)paper in nanostructure form and red CdSe QD *** highest bandwidth for CsPbBr3 PQD paper,229 MHz,is achieved with a blue micro-LED pumping source and a high data transmission rate of 400 Mbps;this is very promising for VLC *** 817 MHz maximum bandwidth and a 1.5 Gbps transmission speed are attained by the proposed semipolar blue *** proposed flexible white light system and the high-bandwidth PQD paper could pave the way for VLC wearable devices.

关键词： pumping communication quantum

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Enhanced-SETL: A multi-variable deep reinforcement learning approach for contention window optimization in dense Wi-Fi networks

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computer Networks 2024年 253卷

作者： Tu, Yi-Hao Lin, En-Cheng Ke, Chih-Heng Ma, Yi-Wei Department of Electrical Engineering National Taiwan University of Science and Technology Taipei106335 Taiwan Master Program of Information Technology and Applications National Quemoy University Kinmen892009 Taiwan Department of Computer Science of Information Engineering National Quemoy University Kinmen892009 Taiwan

In this paper, we introduce the Enhanced Smart Exponential-Threshold-Linear (Enhanced-SETL) algorithm, a new approach that uses the multi-variable Deep Reinforcement Learning (DRL) framework to simultaneously optimize multiple settings of the Contention Window (CW) in IEEE 802.11 wireless networks. Unlike traditional DRL methods that adjust only a single CW parameter, our innovative approach simultaneously optimizes both the CW minimum (CWmin) and CW Threshold (CWThreshold), significantly improving network traffic control. We utilize a Double Deep Q-learning Network (DDQN) for dynamic updates of these CW settings, broadcasted across the dense Wi-Fi networks. This dual adjustment method, coupled with dynamic, data-driven updates, not only enhances throughput, but also reduces collision rates, and ensures fairness access across both static and dynamic wireless environments. Enhanced-SETL achieves a throughput improvement ranging from 3.55% up to 43.73% and from 3.98% up to 30.15% in static and dynamic scenarios over standard protocols and state-of-the-art DRL models, while maintaining a fairness index near 99% across diverse stations, showcasing its effectiveness and adaptability in various network conditions. © 2024

关键词： Wireless local area networks (WLAN)

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Thermodynamic and Environmental Assessment of Low-GWP Alternative Refrigerants for Domestic Cooling

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Journal of The Institution of Engineers (India): Series C 2023年第2期104卷 377-383页

作者： Islam, Md. Amirul Rupam, Tahmid Hasan Hosan, Shahadat Saha, Bidyut Baran Institute for Materials Chemistry and Engineering Kyushu University Kasuga-Koen 6-1 Kasuga-Shi Fukuoka816-8580 Japan Department of Electrical and Electronics Engineering Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj8100 Bangladesh Kyushu University 744 Motooka Nishi-Ku Fukuoka819-0395 Japan Kyushu University Program for Leading Graduate School Green Asia Education Center Kyushu University Fukuoka Japan Department of Mechanical Engineering Kyushu University 744 Motooka Nishi-Ku Fukuoka819-0395 Japan

Nearly two billion air-conditioning (AC) units are currently being used for space cooling worldwide. The majority of these ACs use R134a as the working fluid, a greenhouse gas (GHG) with a global warming potential (GWP) of 1300 kg-CO2-eq. According to the rules set by the world environment safety organizations, the GWP of domestic air-conditioning systems must not exceed 750 kg-CO2-eq. Hence, the R134a must be phased out by 2025, and an alternative refrigerant with similar thermodynamic properties yet low GWP is required. Therefore, the authors have investigated several potential binary/ternary refrigerant blends in this study. Among the studied refrigerants, R445A, R30A, and NPB2 (newly proposed blend: 8% R152a + 92% R1234yf) can reduce 90–99% global warming impact (more than 200 million tonnes of CO2 emission equivalent) caused by the domestic air-conditioning systems every year. © 2023, The Institution of Engineers (India).

关键词： Refrigerants

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Surface engineering Towards Boosted Dielectric Properties for High-Temperature Polymers Under electrical Extremes

Surface Engineering Towards Boosted Dielectric Properties fo...

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Conference on electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Jierui Zhou Marina Dabaghian Anna Marie LaChance Jing Hao Wesley Zhong Luyi Sun Yang Cao Department of Electrical and Computer Engineering University of Connecticut Storrs CT USA Electrical Insulation Research Center Institute of Materials Science University of Connecticut Storrs CT USA Department of Chemical and Biomolecular Engineering University of Connecticut Storrs CT USA Polymer Program Institute of Materials Science University of Connecticut Storrs CT USA

Polymer-thin films are critical dielectric materials for capacitive energy storage in power and electronic systems. The rapid development of wide bandgap semiconductors urgently calls for polymers that can attain high energy density and high charge-discharge efficiency at elevated temperatures. However, high-temperature polymers usually suffer from compromised dielectric breakdown strength and soaring conduction loss due to the intrinsic constraint between their bandgaps and thermal stability. In this work, we propose a facile and high throughput interface engineering technique utilizing nanocoatings formed by montmorillonite (MMT) nanoclays, which can serve as an out-of-the-box solution to bypass this constraint. The highly ordered MMT-based nanocoatings with layered structure can significantly block the excessive charge injection at high electric fields and dissipate the charge carriers along the in-plane direction. The MMT-coated PI films exhibit improved breakdown strength, suppressed conduction loss, and boosted charging-discharging efficiency. This work holds the promise of improving the dielectric properties of polymers through surface engineering, enabling their application at concurrent electrical and thermal extremes.

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Selective incorporation of antimony into gallium nitride

arXiv

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arXiv 2024年

作者： Liu, Yujie Navid, Ishtiaque Ahmed Mi, Zetian Kioupakis, Emmanouil Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan 1301 Beal Avenue Ann ArborMI48109 United States

Dilute concentrations of antimony (Sb) incorporation into GaN induce strong band-gap bowing and tunable room-temperature photoluminescence from the UV to the green spectral regions. However, the atomistic details of the incorporation of Sb into the GaN host remain unclear. In this work, we use first-principles calculations to understand the thermodynamics of Sb substitution into GaN, and its effect on the optical and Raman spectra. Although it is empirically considered that Sb is preferentially incorporated as an anion (Sb3–) into the N sublattice, we demonstrate that Sb can also be incorporated as a cation (Sb3+, Sb5+) into the metal sublattice. Our thermodynamic analysis demonstrates that SbN0, SbGa2+, and SbGa0 can co-exist under Ga-rich conditions in n-type samples. We further confirm the dual incorporation of Sb by calculating the vibrational frequencies of different anionic and cation substitutions to explain the origins of experimentally observed additional Raman peaks of Sb-doped GaN. Moreover, the calculated band structures of different Sb substitutions into GaN explain the experimental photoluminescence and optical absorption spectra. Overall, our analysis suggests that the coexistence of Sb3–, Sb3+, and Sb5+ substitutions into GaN explains the totality of experimental measurements. Our results demonstrate that the selective incorporation of Sb into GaN (and potentially other group-V elements such as As, P, or Bi) by tuning the growth conditions can drastically modify the electronic properties, for applications in visible light emitters and photocatalysis. Copyright © 2024, The Authors. All rights reserved.

关键词： Gallium nitride

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Computational analysis of LiMgI3: a promising material for solar energy conversion

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RSC advances 2025年第23期15卷 17906-17932页

作者： Md Raihan Kabir Nazmul Shahadath Md Tarekuzzaman Md Abu Bakkar Siddique O Alsalmi Md Rasheduzzaman Md Abdul Qader M Moazzam Hossen Md Zahid Hasan Materials Research and Simulation Lab Department of Electrical and Electronic Engineering International Islamic University Chittagong Kumira Chittagong 4318 Bangladesh zahidhasan.02@***. Department of Electrical and Electronic Engineering International Islamic University Chittagong Kumira Chittagong 4318 Bangladesh. Department of Physics College of Science Umm Al-Qura University Makkah 21955 Saudi Arabia. Department of Electrical and Computer Engineering Lamar University PO Box 10078 Beaumont TX 77710 USA. Department of Computer Science and Engineering International Islamic University Chittagong Kumira Chittagong 4318 Bangladesh.

This work employs density functional theory (DFT) using CASTEP to investigate the structural, electronic, and optical properties of cubic LiMgI as an absorber material. The lattice parameters we examined match quite well with earlier theoretical results, and the phonon dispersion confirmed its dynamic stability. The electronic band structure and density of states (DOS) revealed that LiMgI is a semiconductor, with band gaps of 1.162 eV using the GGA method and 1.922 eV using the HSE06 hybrid functional. Optical properties were evaluated within the photon energy range of 0-14 eV, key optical characteristics-such as absorption coefficient, reflectivity, refractive index, dielectric response, optical conductivity, and energy loss, all indicating excellent light-harvesting potential. To assess its device applicability, SCAPS-1D simulation software was used to model various solar cell architectures with LiMgI as the absorber. A total of 60 configurations combining different electron transport layers (ETLs) such as WS, IGZO, TiO, ZnO, ZnS, and PCBM, and hole transport layers (HTLs) like CuO, CuO, CBTS, CuI, P3HT, PEDOT:PSS, CuSCN, Spiro-OMeTAD, PTAA, and CdTe were evaluated. The ITO/WS/LiMgI/CuO/Ni structure yielded the best performance, with a power conversion efficiency (PCE) of 20.73%, open circuit voltage ( ) of 1.495 V, a short circuit current ( ) of 15.78 mA cm, and fill factor (FF) of 87.81%. This study analyzes how absorber and electron transport layer (ETL) thickness affect key photovoltaic parameters. It also examines the valence band offset (VBO) and conduction band offset (CBO) characteristics of different ETLs. The study further investigates the impact of series and shunt resistances, temperature, quantum efficiency (QE), capacitance-voltage (-) Characteristics, generation-recombination response, current density-voltage (-) characteristics, and impedance spectra on improving device performance. The exceptional photon capture efficiency of LiMgI perovskite sola

关键词： Quantum efficiency

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Generation and manipulation of skyrmions and other topological spin structures with rare metals

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Rare Metals 2022年第7期41卷 2200-2216页

作者： Chu Ye Lin-Lin Li Yun Shu Qian-Rui Li Jing Xia Zhi-Peng Hou Yan Zhou Xiao-Xi Liu Yun-You Yang Guo-Ping Zhao College of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610068China Center for Magnetism and Spintronics Sichuan Normal UniversityChengdu 610068China Guangdong Provincial Key Laboratory of Optical Information Materials and Technology Guangzhou 510006China Institute for Advanced Materials South China Normal UniversitySouth China Academy of Advanced OptoeletronicsGuangzhou 510006China School of Science and Engineering The Chinese University of Hong KongShenzhen 518172China Department of Electrical and Computer Engineering Shinshu UniversityNagano 380-8553Japan

Skyrmions are nano-scale quasi-particles with topological protection,which have potential applications in next-generation spintronics-based information *** papers have been published to review various aspects of skyrmions,including physics,materials and ***,no review paper has focused on rare metals which play important roles in nucleating and manipulating skyrmions and other topological *** this paper,various roles of rare metals have been classified and summarized,which can tune Curie temperature(TC),Dzyaloshinskii-Moriya interaction(DMI),magnetocrystalline anisotropy,Ruderman-Kittel-Kasuya-Yosida(RKKY)interaction and four-spin interaction so as to trigger the generation of skyrmions and other topological spin *** materials covered include typical B20 crystals,various layered systems with interfacial DMI,frustrated materials,antiferromagnets,ferrimagnets,twodimensional(2D)materials,*** addition,the rare-earth(RE)permanent magnets can provide an energy barrier and enrich the dynamic behaviors of skyrmions,which has also been reviewed.

关键词： Magnetic skyrmions Rare metals Generation and manipulation

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Optimizing Different Methods of Fabricating 3D Printed UV Blocking Sheets for Solar Cells

Optimizing Different Methods of Fabricating 3D Printed UV Bl...

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Renewable Energy Technologies and Modern Communications Systems: Future and Challenges, Conference on

作者： Amjad Fawzi Alhindi Lujain Khalid Baawad Fahad Allam Nazek Elatab Rabab R. Bahabry Smart Advanced Memory Devices and Applications (SAMA) Laboratory Electrical and Computer Engineering Computer Electrical Mathematical Science and Engineering King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia Materials Science and Engineering Department King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia Department of Physical Sciences University of Jeddah (UJ) College of Science Jeddah Saudi Arabia

ISBN: (数字)9798331519445

ISBN: (纸本)9798331519452

This study investigates the fabrication of innovative UV-blocking sheets that effectively transmit visible light while simultaneously obstructing harmful ultraviolet (UV) radiation, utilizing Cerium Oxide (CeO2) and Zinc Oxide (ZnO) nanoparticles as UV-blocking agents. Three distinct fabrication methods were explored: The Powder Method, where nanoparticles were incorporated directly into polydimethylsiloxane (PDMS); the Ball milling Mixture method, which involved mixing nanoparticles through ball milling; and the Solvent-Based Mixture method, where nanoparticles were dissolved, mixed, and dried; before incorporation into PDMS. Samples were produced using a 3D printing technique, which is Direct Ink Writing (DIW) and characterized for their optical properties via UV-Vis spectroscopy. The results indicated CeO2 demonstrated superior UV-blocking capabilities (a maximum blockage of ~99%) compared to ZnO, while maintaining high transmittance for visible light (a maximum of ~90%). Notably, the solvent-based method exhibited better results than the ball milling method; however, the powder method had the best results. Therefore, this investigation offers a promising solution for solar panel protection that aligns with Saudi Arabia's Vision 2030 energy objectives. The relentless exposure of devices, particularly solar cells, to harmful UV radiation poses a formidable challenge and leads to annual degradation rates of between -0.8% and -4.9%, besides other factors. These findings underscore the critical importance of developing effective UV-blocking solutions.

关键词： Nanoparticles Powders II-VI semiconductor materials Photovoltaic cells Ink Ball milling Writing Zinc oxide Three-dimensional printing Substrates

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Metasurfaces That Enable Bottle-Beam Arrays for Neutral Atom Trapping

Metasurfaces That Enable Bottle-Beam Arrays for Neutral Atom...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Fang, Chengyu Kim, Minjeong Czaplewski, David A. Mei, Hongyan Deshpande, Sanket Yu, Zhaoning Xiao, Yuzhe Yang, Xuting Dibos, Alan M. Saffman, Mark Choy, Jennifer T. Kats, Mikhail A. Department of Electrical and Computer Engineering University of Wisconsin-Madison MadisonWI53706 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60349 United States Department of Physics University of Wisconsin-Madison MadisonWI53706 United States Department of Physics University of North Texas DentonTX76201 United States Department of Material Science and Engineering University of Wisconsin-Madison MadisonWI53706 United States

We report optical metasurfaces that enable bottle-beam arrays for blue-detuned trapping of neutral atoms. Our approach only requires a single metasurface which significantly reduces the complexity of the trapping expe... 详细信息

关键词： Atoms

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In-situ real-time monitoring of GeSn growth using UHV-CVD to achieve high-quality material with lasing at 2250 nm and 100 K [Invited]

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Optical materials Express 2025年第6期15卷 1371-1381页

作者： Joshua Grant Sudip Acharya Alexer Golden Enbo Yang Hryhorii Stanchu Guo-En Chang Greg Sun Wei Du Shui-Qing Yu Department of Electrical Engineering and Computer Science University of Arkansas Fayetteville AR 72701 USA Material Science and Engineering Program University of Arkansas Fayetteville AR 72701 USA Institute for Nanoscience and Engineering University of Arkansas Fayetteville AR 72701 USA Department of Mechanical Engineering National Chung Cheng University Chiayi 62102 Taiwan Department of Engineering University of Massachusetts Boston MA 02125 USA

GeSn alloys hold great promise for the development of Si photonics due to its direct bandgap with sufficient high Sn composition, tunable bandgap energies covering broad infrared wavelength range, and compatibility with the complementary metal-oxide-semiconductor (CMOS) process. For the past decades, tremendous efforts have been made to develop material growth recipes to obtain device-level material quality using chemical vapor deposition (CVD) reactors. A common issue in material growth is the formation of Sn droplets (i.e., Sn segregation) that seriously degrades the material quality. However, although industrial CVD has delivered high-quality materials for device demonstration, the dynamic process of material growth remains unavailable, and only ex-situ material characterizations could provide feedback. In this work, a specially designed ultra-high-vacuum CVD (UHV-CVD) was used to study the growth dynamic by employing an in-situ optical system, which enables us to monitor the formation of Sn droplets in real-time. The Sn segregation occurring at the cooling stage after growth completion rather than during material growth was discovered, indicating that a post-growth treatment is needed to minimize the Sn droplet formation. By extending the GeSn growth time and controlling the cooling cycle, the number of Sn droplets dramatically reduced, leading to a high-quality strain-relaxed GeSn layer with 10.2% Sn composition and over 730 nm thickness. Material quality is comparable with those grown using commercial RPCVD in the early stage, which was further confirmed by the demonstration of an optically pumped laser. A threshold of ∼600 kW/cm 2 at 77 K and a maximum operating temperature of 100 K were obtained, with the lasing peak at ∼2250 nm.

关键词： Avalanche photodiodes Fourier transform infrared spectroscopy Laser sources materials processing Physical vapor deposition Thin films

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