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Potential energy shift of the Fermi level at plasmonic structures for light-energy conversion determined by graphene-based Raman measurements
摘要： Single layer graphene was used to determine the electrochemical potential of plasmonic nano-structures for photoelectrochemical energy conversions. From electrochemical Raman measurements of the graphene layer under near-infrared light, illumination has revealed the relationship between the photoenergy conversion ability and the Fermi level of the plasmonic structure. The determination is based on in situ monitoring of G and 2D Raman bands of the graphene layer on plasmonic structures. The correlation plots of G and 2D bands show the dependence on the photoconversion ability. The present electrochemical Raman measurements provide detailed understanding of the plasmon-induced charge transfer process for further developments on the ability.
关键词： plasmonic structures,Raman measurements,graphene,Fermi level,photoelectrochemical energy conversion
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Symposium on Applications of Ferroelectrics (ISAF) - Lausanne, Switzerland (2019.7.14-2019.7.19)] 2019 IEEE International Symposium on Applications of Ferroelectrics (ISAF) - Vibrating Piezoelectric Energy Conversion Efficiency of Sol-Gel PZT Films with Various Crystal Orientations on MEMS Buckled Diaphragm Structures
摘要： Vibrating energy conversion efficiency was investigated on piezoelectric transducers fabricated on MEMS buckled diaphragm structures from the viewpoint of crystal orientation of sol-gel derived lead-zirconate-titanate (PZT) films. The crystal orientation dominates in-plane stress and spontaneous polarization direction of the PZT films. The in-plane stress affects the static buckling of the diaphragm where a large convex buckling results in a high mechanical conversion efficiency from the flexural vibration to the in-plain vibration. The polarization direction affects the intrinsic piezoelectric conversion efficiency. The crystal orientation of the sol-gel PZT was controlled through pyrolysis temperature between 250?C and 350?C, resulting in a texture variation from (100)-oriented films to (111)-oriented ones. Highly (111)-oriented films showed large polarizations but small buckling deflections, while highly (100)-oriented films showed vice versa. Intermediately textured films with 40–45% (111)-orientation index showed the highest conversion efficiency.
关键词： Piezoelectric,Sol-gel,Residual stress,Buckling,PZT,Polarization,Energy conversion,Diaphragm
更新于2025-09-19 17:13:59
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Ultra-thin films of barium fluoride with low work function for thermionic-thermophotovoltaic applications
摘要： The deposition of barium fluoride thin and ultra-thin films on gallium arsenide substrates was performed by electron beam evaporation for analyzing the influence of film thickness and chemical composition on the work function of the resulting heterostructure. X-ray photoemission spectroscopy combined with ultraviolet photoemission spectroscopy measurements reveals that films of 2 nm nominal thickness and Ba/F ? 1.0 stoichiometry ratio induce the achievement of a significantly low work function of 2.1 eV to the BaFx/GaAs heterostructure. The significant reduction of the work function at least down to 3.0 eV is confirmed by a test thermionic converter operating at a cathode temperature of 1385 C, where the heterostructure was applied as anode. The low work function, together with a negligible optical absorption, makes feasible the practical application of barium fluoride coatings on GaAs within hybrid thermionic-thermophotovoltaic devices.
关键词： Ultraviolet photoemission spectroscopy,Work function,Barium fluoride,Thermionic-thermophotovoltaic energy conversion
更新于2025-09-19 17:13:59
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Hybrid Plasmonic‐Aerogel Materials as Optical Superheaters with Engineered Resonances
摘要： Solar radiation is a versatile source of energy, convertible to different useful forms of power. A direct path to exploit it is the generation of heat, for applications including passive building heating, but it can also drive secondary energy conversion steps. We present a novel concept for a hybrid material which is both strongly photo-absorbing and with superior characteristics for the insulation of heat. The combination of that two properties is rather unique, and make of this material an optical superheater. To realize such material, we are combining plasmonic nanoheaters with alumina aerogel. In our hybrid material, the aerogel has the double function of providing structural support for plasmonic nanocrystal, which serve as nanoheaters, and reducing the diffusion rate of the heat generated by them, resulting in large local temperature increases under a relatively low radiation intensity. Alongside their optical and photothermal properties, this work includes theoretical discussion on the physical mechanisms impacting the system’s balanced thermal equilibrium.
关键词： hybrid aerogel,photoheater,energy conversion,surface plasmon resonance,gels
更新于2025-09-19 17:13:59
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Transforming Energy Using Quantum Dots
摘要： Colloidal quantum dots (QDs) have emerged as versatile and efficient scaffolds to absorb light and then manipulate, direct, and convert that optical energy into other useful forms of energy. The QD characteristics (optical, electrical, physical) can be readily tuned via solution phase chemistries in order to affect the flow of energy, that was initially contained in the photons of light, using rational designs. Key parameters under control are the size and shape, internal composition (e.g., alloys, core/shell heterostructures, semiconductor/metal interfaces), surface composition (ligand chemistries), and film composition (e.g., QD-QD electronic coupling, bulk heterostructure formation, QD/biological interfaces). In this review, we summarize recent progress using QDs in energy conversion architectures with the express goal of converting optical energy to other forms of energy, including electricity, photons with different energies, and chemical bonds, i.e., photovoltaics, photon up-or down-conversion, and photocatalytic process, respectively. The advantages of using QDs in absorbing and then directing and converting optical energy over molecular chromophores are highlighted. Finally, we discuss ongoing challenges and opportunities associated with using QDs for absorbing, manipulating and directing the flow of energy.
关键词： quantum dots,energy conversion,photon up-conversion,photon down-conversion,photocatalysis,photovoltaics
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) - Bulk Power System Dynamics with Varying Levels of Synchronous Generators and Grid-Forming Power Inverters
摘要： The conversion of electrical to mechanical power on a sub-centimeter scale is a key technology in many microsystems and energy harvesting devices. In this paper, we present a type of a capacitive energy conversion device that uses capillary pressure and electrowetting to reversibly convert electrical power to hydraulic power. These microhydraulic actuators use a high surface-to-volume ratio to deliver high power at a relatively low voltage with an energy conversion efficiency of over 65%. The capillary pressure generated grows linearly with shrinking capillary diameter, as does the frequency of actuation. We present the pressure, frequency, and power scaling properties of these actuators and demonstrate that power density scales up as the inverse capillary diameter squared, leading to high-efficiency actuators with a strength density exceeding biological muscle. Two potential applications for microhydraulics are also demonstrated: soft-microrobotics and energy harvesting.
关键词： microsystems,electrocapillary,soft robotics,PDMS,actuator,energy conversion,microfluidics,electrowetting,energy harvesting,porous materials,Microhydraulics,microrobotics
更新于2025-09-16 10:30:52
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Synthesis and properties of a novel porphyrin–fullerene triad assembled through donor–acceptor bonding
摘要： Complexation of (hydroxy)(oxo)(5,10,15,20-tetraphenylporphyrinato) molybdenum(v) with 2',5'-di(2-pyridyl)-1'-(3-pyridyl methyl)pyrrolidino[70]fullerene leading to a new donor–acceptor triad is characterized by quantitative description of the equilibrium and the reaction rate. The prospects of the triad as a photosynthetic antenna imitator and an active layer in solar energy conversion devices are substantiated.
关键词： solar energy conversion,porphyrin–fullerene triad,donor–acceptor bonding,photosynthesis
更新于2025-09-16 10:30:52
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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) - Retaining 3D Laser Pulse Shape at Sum Frequency Generation Processes
摘要： Modern photoinjectors require to use 3D profiled laser pulses for irradiation of cathode surface. The pulses make it possible to control a space-charge distribution of generated electron bunches and, in particular, to form electron bunches with cylindrical and 3D ellipsoidal shapes. Spatial light modulators (SLM) [1,2] and profiled volume Bragg gratings [3] can be used for control 3D intensity distribution of linearly chirped broadband infrared laser pulses. But, the widely used in photoinjectors Cs2Te photocathodes have the highest efficiency in UV spectral range. So, the important task is to transform the profiled 3D (x,y,t) infrared pulses to visible and UV regions with high energy conversion efficiency and preserving 3D intensity distribution. It can be done with help of second, fourth and third harmonic generation (SHG, FHG, THG) processes at low group velocity mismatch of the interacted pulses. The control of the group velocities can be done by a creation of amplitude tilt or angular chirp. Here we present results of numerical simulations of SHG, FHG and noncollinear THG processes implemented for laser pulses with central wavelength 744 nm, 6 nm spectral width (FWHM) and pulse duration 15 ps (FWHM). The initial fundamental pulse has ellipsoidal 3D shape with linear growth intensity in time.
关键词： energy conversion efficiency,3D laser pulse shape,sum frequency generation,harmonic generation,photoinjectors
更新于2025-09-16 10:30:52
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Bulk and localized plasmonic heating in nanogold doped polymers
摘要： Colloidal gold (Auc) nanoparticles (GNPs) and nanorods (GNRs) were incorporated into polymer blend ?lms and electrospun ?bers to utilize the nanoparticle plasmonic response for localized heating of the polymer. In this work, mathematical modeling was used to describe the GNP distribution and heat/melt pro?le surrounding each GNP in the polymer blend, demonstrating that a bulk temperature change of only 0.2 °C results in a 20-nm-diameter melted polymer sphere around the GNP. In addition, it was shown that by reducing the radius of polymer material around the GNP through the use of electrospinning ?bers in place of thin ?lm deposition, heating of the bulk material increased by 72%. Bulk heating of polymer blend ?lms containing either GNPs or GNRs was mapped using an infrared camera system with light-emitting diodes (LEDs) at 530 and 810 nm. The change in temperature observed in the thin ?lms was used to calculate the photo-thermal energy conversion ef?ciency of the respective nanogold doped polymer thin ?lms. Signi?cantly, GNR-doped ?lm ef?ciencies recorded were up to 6.6 times (558.6% increase) that of the polymer blend-only ?lm when interrogated at 810 nm, while the GNP-doped ?lm ef?ciency increased by 1.8 times (75.7% increase) under the 530 nm LED.
关键词： nanogold doped polymers,photothermal energy conversion,electrospun fibers,plasmonic heating
更新于2025-09-16 10:30:52
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Application of Polyoxometalate-Ionic Liquids (POM-ILs) in Dye-Sensitized Solar Cells (DSSCs)
摘要： Polyoxometalates (POMs) as anionic metal oxides are promising candidates for application in dye-sensitized solar cells (DSSCs) due to their peculiar properties including a reversible and multi-electron redox behavior. In this work, four polyoxometalate as ionic liquids (POM-ILs) based on the combination between phosphomolybdate anion (PMo12O40 3-) and organic cations such as [BMIM]+, [BPy]+, [HDPy]+ and [P6,6,6,14]+ were prepared and characterized. A detailed chemical structural elucidation by elemental analysis, ATR-FTIR, 1H and 31P NMR spectroscopies have been performed. These POM-ILs were tested as photosensitizers by adsorption to the photoanode (TiO2 film) for different times (15 minutes to 17 hours). The DSSCs performance can be highly improved comparing the commercially available compound and POM-ILs. The electrodeposition process is an excellent alternative to adsorption in order to improve the overall efficiencies. In general, [BPy]3[PMo12O40] and [P6,6,6,14]3[PMo12O40] are the most promissory compounds for DSSC approaches.
关键词： Dye-Sensitized Solar Cells,Electrodeposition,Ionic Liquids,Polyoxometalate,Energy Conversion Efficiency
更新于2025-09-16 10:30:52