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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Periodic Amplification of Radiative Heat Transfer
摘要： The thermal excitation of materials with a periodic heat flux or temperature modulated in time is a reliable and accurate tool usually applied to determine thermal properties, through techniques such as thermoreflectance, photothermal radiometry, 3ω, photoacoustics, thermal-wave resonant cavity, etc. Moreover, over the past years, the control of heat flux has been improved by means of phase-change materials (PCMs), whose internal structures are strongly driven by their temperature, which results in significant variations of their thermal, optical, and electrical properties. Thermochromic materials (VO2, nitinol) or superconductors are examples of such PCMs, where the material can be either in an insulator phase, with low thermal/electrical conductivity and high emissivity, or in a metallic one characterized by a high thermal/electrical conductivity and low emissivity. This metal-insulator transition (MIT) occurs at the critical temperature of each PCM and can therefore be used to tune the heat currents that the PCM exchanges with the environment, which paves the wave for novel applications.
关键词： radiative heat transfer,metal-insulator transition,thermochromic materials,thermal excitation,phase-change materials
更新于2025-09-11 14:15:04
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Phase‐Change Materials Based Nanoparticles for Controlled Hypoxia Modulation and Enhanced Phototherapy
摘要： Tumor hypoxia strengthens tumor resistance to different therapies especially oxygen involved strategies, such as photodynamic therapy (PDT). Herein, the thermal responsive phase change materials (PCM) are utilized to coencapsulate ultrasmall manganese dioxide (sMnO2) and organic photosensitizer IR780 to obtain IR780-sMnO2-PCM nanoparticles for controlled tumor hypoxia modulation and enhanced phototherapy. The thermal responsive protective PCM layer can not only prevent IR780 from photodegradation, but also immediately release sMnO2 to decompose endogenous H2O2 and generate enough oxygen for PDT under laser irradiation. Owing to the efficient accumulation of IR780-sMnO2-PCM nanoparticles in tumor under intravenous injection as revealed by both florescence imaging and photoacoustic imaging, the tumor hypoxia is greatly relieved. Furthermore, in vivo combined photothermal therapy (PTT) and PDT, IR780-sMnO2-PCM nanoparticles, compared to IR780-PCM nanoparticles, exhibit better performance in inhibiting tumor growth. The results highlight the promise of IR780-sMnO2-PCM in controlled modulation of tumor hypoxia to overcome current limitations of cancer therapies.
关键词： hypoxia modulation,cancer theranostics,photodynamic therapy,phase change materials
更新于2025-09-11 14:15:04
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Photovoltaic–thermal (PV/T) technology: a comprehensive review on applications and its advancement
摘要： Over the most recent couple of decades, tremendous consideration is drawn towards photovoltaic–thermal systems because of their advantages over the solar thermal and PV applications. This paper intends to show different electrical and thermal aspects of photovoltaic–thermal systems and the researches in absorber design modification, development, and applications. From the previous review articles, it has been concluded that the heat energy exhausted from the PV module can be further utilized in different ways and helps in achieving better efficiency. Furthermore, the types of photovoltaic–thermal systems such as air collector, water collector, and combi system, coupling with heat pump and their application to buildings are also stated. This paper also discussed certain design aspects like modifications in the flow channel by adding fins, thin metallic sheets, roll-bond absorber, and porous media and the effect of these modifications on the hybrid system’s efficiency. Furthermore, the use of the latest technologies such as nanofluids, thermoelectric generators, and phase-change materials improves the overall system performance. The role of soft-computing techniques is forecasting the impact of various parameters on the photovoltaic–thermal system is also discussed.
关键词： Phase-change materials (PCM),PV/T combi,Thin metallic sheets (TMS),Nanofluids
更新于2025-09-11 14:15:04
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A review on modeling and simulation of solar energy storage systems based on phase change materials
摘要： Phase Change Materials (PCM) have been widely used in different applications. PCM is recognized as one of the most promising materials to store solar thermal energy in the form of latent heat. Utilization of PCMs for solar energy storage compensates for the intermittent characteristic of this energy source. Mathematical modeling and numerical simulation of solar energy storage systems provide useful information for researchers to design and perform experiments with a considerable saving in time and investment. This paper is focused on modeling and simulation of PCM based systems that are used in different solar energy storage applications. A thorough literature review is performed to investigate and compare the results and accuracy of different mathematical models, numerical methods and thermodynamic analysis of using different PCMs in different solar systems. Moreover, the potential research areas in numerical simulations and thermodynamic analysis of solar systems based on PCMs are determined considering the existing gaps in the literature.
关键词： Phase change materials,Solar energy storage systems,Numerical modeling,Simulation
更新于2025-09-10 09:29:36
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Electrically programmable multi-purpose nonvolatile metasurface based on phase change materials
摘要： We propose an electrically programmable nonvolatile metasurface working at near-IR frequency (λ=1550 nm) based on ITO/Ge2Sb2Te5-ITO/Au crossbar structure. The proposed metasurface can dynamically change its optical function by modulating the crystallization level of Ge2Sb2Te5, which is a phase change material, at each pixel position individually by controlled electrical pulses. We design and optimize the metasurface by using finite-difference time-domain simulations and numerically demonstrate various optical functions including beam steering devices, flat lenses, optical vortex generators, and metasurface holograms with a single device geometry.
关键词： metasurfaces,phase change materials,spatial light modulators,reconfigurable metasurfaces,programmable metasurfaces
更新于2025-09-10 09:29:36
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Engineering Interface-Dependent Photoconductivity in Ge <sub/>2</sub> Sb <sub/>2</sub> Te <sub/>5</sub> Nanoscale Devices
摘要： Phase change materials are increasingly being explored for photonics applications, ranging from high resolution displays to artificial retinas. Surprisingly, our understanding of the underlying mechanism of light-matter interaction in these materials has been limited to photothermal crystallization, because of its relevance in applications such as re-writable optical discs. Here we report a photoconductivity study of nanoscale thin films of phase change materials. We identify strong photoconductive behaviour in phase change materials, which we show to be a complex interplay of three independent mechanisms: photoconductive, photo induced-crystallization and photo-induced-thermoelectric effects. We find these effects also congruously contribute to a substantial photovoltaic effect, even in notionally symmetric devices. Notably, we show that device engineering plays a decisive role in determining the dominant mechanism; the contribution of the photothermal effects to the extractable photocurrent can be reduced to < 0.4 % by varying the electrodes and device geometry. We then show that the contribution of these individual effects to the photoresponse is phase-dependent with the amorphous state being more photoactive than the crystalline state and that a reversible change occurs in the charge transport from thermionic to tunnelling during phase transformation. Finally we demonstrate photodetectors with an order of magnitude tuneability in photodetection responsivity and bandwidth using these materials. Our results provide insight to the photo-physics of phase change materials and highlight their potential in future opto-electronics.
关键词： Mixed-Mode Operation,Photothermal effects,Tuneable Photodetector,Phase Change Materials,Photoconductivity
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Plasma Preparation of the Top-Quality Phase Change Materials Based on As-Se-Te Chalcogenide System
摘要： The excellence of the Plasma-Enhanced Chemical Vapor Deposition (PECVD) approach in terms of preparation of the top-quality phase change materials based on As-Se-Te chalcogenide ternary system has been demonstrated. The samples were synthesized via direct interaction of arsenic, selenium and tellurium vapors into low-temperature non-equilibrium RF (40 MHz) plasma discharge at low pressure. The amorphous films with high degree of structural and chemical uniformity have been prepared in the broad range of contents, in particular, the chemical compositions going beyond the region of glass formation.
关键词： PECVD,chalcogenide films,phase change materials
更新于2025-09-09 09:28:46
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Metasurfaces for independent manipulation of the wavefronts in the different states of phase change materials
摘要： Metasurfaces have attracted increasing attention due to their extraordinary capability in the arbitrary control of electromagnetic waves. However, most metasurfaces lack flexibility and only enable fixed optical performance once fabricated. In this work, we propose ultra-thin metasurfaces with varied functionalities using phase change materials (PCMs) when phase change occurs on whole structured PCMs, which has not been found in previous reports. The wavefronts in the amorphous and crystalline states of the PCMs can be arbitrarily and independently modulated with high efficiency (～60% and ～40% in the two states, respectively). This work may be valuable for information encryption and optical communications.
关键词： wavefront manipulation,metasurfaces,information encryption,phase change materials,optical communications
更新于2025-09-09 09:28:46
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Photo- and electro-responsive phase change materials based on highly anisotropic microcrystalline cellulose/graphene nanoplatelet structure
摘要： Phase change materials (PCMs) exhibit great potential applications in many fields, such as energy-saving building, solar energy harvesting, waste heat utilization, constant temperature protection and thermal management of microelectronic devices. In this work, we proposed a facile and novel method to prepare the composite PCMs. Through the combination of pre-refrigeration and freeze-drying techniques using the microcrystalline cellulose (MCC)/graphene nanoplatelets (GNPs) hydrogels, which were firstly prepared through solution compounding, gelling and solvent exchanging successively, the porous MCC/GNP aerogels with highly oriented stacking of MCC/GNP were successfully obtained. The composite PCMs based on the highly anisotropic MCC/GNP aerogel and polyethylene glycol (PEG) exhibited relatively high thermal conductivity (1.03 W/mK) at low GNP content (1.51 wt%), high latent heat (182.6 J/g) which was 99.84% of pure PEG, excellent encapsulation ability and mechanical stability. Further results showed that the composite PCMs exhibited excellent solar energy harvesting/electrical energy transformation, storage and release abilities. In addition, a simple heating device was designed to verify the application of the composite PCMs as the temperature protection element. The measurements showed that the presence of the PCMs prevented the rapidly rising of temperature during the heating process while maintained the temperature at relatively high level in a long time during the cooling process.
关键词： Phase change materials,Mechanical stability,Anisotropic structure,Solar energy/electrical energy comprehensive utilization
更新于2025-09-09 09:28:46
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Synthesis of novel form-stable composite phase change materials with modified graphene aerogel for solar energy conversion and storage
摘要： In this study, novel kinds of form-stable composite phase change materials (FS-CPCM) were prepared by the vacuum impregnation method. In the FS-CPCM, lauric acid (LA) was the PCM, and LA was grafted on the surface of graphene aerogel (GA) by an esteri?cation reaction and reduction process to prepare supporting material and increase the thermal conductivity of the FS-CPCMs. The microstructure, thermal storage properties, thermal conductivity and light-to-heat conversion of the FS-CPCMs were investigated. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to demonstrate that the LA was encapsulated e?ectively in the porous structure of the LA-GA, and the LA/LA-GA FS-CPCMs were prepared successfully. X–ray di?ractometer results con?rmed that the crystallization of the LA/LA-GA FS-CPCM was better than that of LA/GA FS-CPCM. Thermal conductivity analyses indicated that the thermal conductivities of the LA/LA-GA-1 FS-CPCMs increased 352.1% and 32.6% compared with the conductivities of LA and LA/GA FS-CPCM, respectively. Di?erential scanning calorimetry results con?rmed that the LA/LA-GA-1 FS-CPCM possess good phase change behavior, low undercooling and excellent thermal cycling stability. The melting enthalpy and freezing enthalpy could reach 207.3 J/g and 205.8 J/g, respectively, and the LA/LA-GA FS-CPCM exhibited good thermal reliability and stability. Furthermore, the LA/LA-GA FS-CPCM had excellent photon absorption and the highest e?ciency in terms of light-to-heat conversion of 80.6%. Such good performances demonstrate the LA/LA-GA FS-CPCM's potential for use in solar energy storage systems.
关键词： Phase change materials,Thermal conductivity,Graphene aerogel,Solar energy conversion
更新于2025-09-04 15:30:14