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Photonic Titanium dioxide film obtained from hard template with chiral nematic structure for environmental application
摘要： In the present work, mesoporous TiO2 with a photonic structure was elaborated using cellulose nanocrystals (CNCs) as a biotemplate by two-step hard template methods. This strategy enables to replicate the chiral nematic (CN) structure of the photonic films (biotemplate) in TiO2 films. A series of iridescent CNCs films with different weight ratios of silica/CNCs composite photonic films were prepared via evaporation induced self-assembly (EISA) method. The films showed iridescent color and tuneable Bragg reflection wavelengths by solely changing the ratio between the silica and the CNCs biotemplate. Polarized optical microscopy (POM) performed on hydride SiO2/CNCs films showed a birefringence and typical fingerprint of chiral nematic structure. This birefringence was also observed for TiO2 films obtained using SiO2 films as a hard template, which suggested the transfer of the chiral nematic structure in TiO2 materials. Afterwards, their optical, morphological and electronic properties were studied by scanning electron microscope (SEM), POM, energy-dispersive X-ray spectroscope (EDX) and time resolved microwave conductivity (TRMC). The photocatalytic activities were evaluated by following the phenol degradation using high performance liquid chromatography (HPLC). The results showed that the structuration of the TiO2 film using a chiral nematic SiO2 film as hard template enhances the photocatalytic performance compared to non-structured mesoporous TiO2.
关键词： hard template,cellulose nanocrystals,iridescent film,evaporation induced self-assembly,light harvesting,phenol degradation,chiral nematic structure
更新于2025-09-23 15:22:29
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Preferred orientation of 2,7-dioctyl[1]benzothieno[3,2- <i>b</i> ][1]benzothiophene molecules on inorganic single-crystal substrates with various orientations
摘要： The organic molecule 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) was deposited on quartz glass, e11 (cid:2)20T A-, (0001) C-, and e1 (cid:2)102T R-single-crystal Al2O3 (sapphire), and (100)-, and (111)-single-crystal MgO substrates by vacuum thermal evaporation, and structural characterizations were carried out by X-ray di?raction analysis and atomic force microscopy (AFM) observation. The (001) out-of-plane orientation with a similar in-plane orientation was obtained irrespective of the substrate material and orientation, and its formation was governed by π–π-stacking-induced molecular ordering. The degree of orientation was re?ected by the grain structure related to the substrate material. The growth model of the oriented C8-BTBT layer was speculated on the basis of experimental results.
关键词： π–π-stacking,vacuum thermal evaporation,X-ray diffraction,C8-BTBT,atomic force microscopy
更新于2025-09-23 15:21:21
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Investigation on annealing temperature-dependent optical properties of electron beam evaporated ZnSe thin films
摘要： This research work is devoted to studying optical properties of zinc selenide (ZnSe) thin films deposited by electron beam evaporation technique and annealed at different temperatures in a nitrogen environment. The structural analysis by X-ray diffraction confirmed that the obtained ZnSe films had cubic zinc-blende structure with preferred orientation along plane (111). Based on Swanepoel's envelope method, some important optical parameters such as absorption coefficient, extinction coefficient, refractive index and optical band gap, were evaluated through the transmission spectrum ranging from 300 to 1500 nm at room temperature. The optical band gap increased from 2.52 to 2.65 eV with the increasing annealing temperature. However, both the thickness and refractive index of the films decreased. In addition, the dispersion parameters of the refractive index and energy were also studied by using Wemple-DiDomenico single oscillator model.
关键词： Optical properties,Thin films,Electron beam evaporation,Zinc selenide,Thermal annealing
更新于2025-09-23 15:21:21
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Generation of ZnO nanoparticles for long-term exposure experiments
摘要： A method of continual ZnO nanoparticle generation was tested for use in follow-up long-term inhalation exposure experiments with small laboratory animals. Nanoparticles were synthesized in an externally heated tube reactor by the evaporation of metallic zinc into a stream of nitrogen carrier gas, followed by the oxidation of zinc vapor in a stream of air and the formation of nanoparticles by a chemical vapor condensation method. The nanoparticle production was studied at various evaporation temperatures, reactor flow rates and flow rates of mixing air. Particle generation for more than 100 h in two experimental runs with one batch of the zinc precursor was performed without a considerable decrease in the particle production rate. As a result, particle production with a number concentration much greater than 1.0 107 #/cm3, a mean particle/agglomerate size well below 50 nm and an emission rate greater than 5 μg/min was obtained under most of the investigated experimental conditions. A maximum emission rate of 16.3 μg/min was obtained at an evaporation temperature of 530 °C, a reactor flow rate of 800 cm3/min and a mixing flow rate of 2000 cm3/min and could be further increased by an increase in the evaporation temperature. The particle characteristics were studied, and estimates of the lung surface deposition area were calculated on the basis of the model developed by the International Commission of Radiological Protection.
关键词： ZnO nanoparticles,Nanoparticle generation,Evaporation/CVS method,LSDA,Hot-wall reactor
更新于2025-09-23 15:21:21
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Solar-driven interfacial evaporation
摘要： As a ubiquitous solar-thermal energy conversion process, solar-driven evaporation has attracted tremendous research attention owing to its high conversion efficiency of solar energy and transformative industrial potential. In recent years, solar-driven interfacial evaporation by localization of solar-thermal energy conversion to the air/liquid interface has been proposed as a promising alternative to conventional bulk heating-based evaporation, potentially reducing thermal losses and improving energy conversion efficiency. In this Review, we discuss the development of the key components for achieving high-performance evaporation, including solar absorbers, evaporation structures, thermal insulators and thermal concentrators, and discuss how they improve the performance of the solar-driven interfacial evaporation system. We describe the possibilities for applying this efficient solar-driven interfacial evaporation process for energy conversion applications. The exciting opportunities and challenges in both fundamental research and practical implementation of the solar-driven interfacial evaporation process are also discussed.
关键词： energy conversion,thermal insulators,thermal concentrators,solar absorbers,evaporation structures,interfacial evaporation,solar-driven evaporation,solar-thermal energy conversion
更新于2025-09-23 15:21:01
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Effect of film thickness and evaporation rate on co-evaporated SnSe thin films for photovoltaic applications
摘要： SnSe thin films were deposited by a co-evaporation method with different film thicknesses and evaporation rates. A device with a structure of soda-lime glass/Mo/SnSe/CdS/i-ZnO/ITO/Ni/Al was fabricated. Device efficiency was improved from 0.18% to 1.02% by a film thickness of 1.3 mm and evaporation rate of 2.5 ? s?1 via augmentation of short-circuit current density and open-circuit voltage. Properties (electrical, optical, structural) and scanning electron microscopy measurements were compared for samples. A SnSe thin-film solar cell prepared with a film thickness of 1.3 mm and evaporation rate of 2.5 ? s?1 had the highest electron mobility, better crystalline properties, and larger grain size compared with the other solar cells prepared. These data can be used to guide growth of high-quality SnSe thin films, and contribute to development of efficient SnSe thin-film solar cells using an evaporation-based method.
关键词： SnSe thin films,film thickness,co-evaporation,photovoltaic applications,evaporation rate
更新于2025-09-23 15:21:01
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Improved Performance of Thermally Evaporated Sb2Se3 Thin-Film Solar Cells via Substrate-Cooling-Speed Control and Hydrogen-Sulfide Treatment
摘要： Antimony selenide is a promising abundant absorber material for solar cells. However, current Sb2Se3 photovoltaic devices, which are fabricated via thermal evaporation, tend to have stoichiometric problems and show suboptimal performance. In this paper, we use a modified thermal evaporator to fabricate high-quality Sb2Se3 films. By dedicatedly cooling the substrate, we can improve both the Sb2Se3 morphology and the Sb2Se3/CdS heterojunction interface substantially. We find a suitable annealing atmosphere, H2S, which can largely compensate for possible deficiencies of Se and remove the antimony-oxide layer on the film surface. Thanks to cooling control and H2S treatment, we obtain a significantly improved efficiency (6.24%) for the Sb2Se3 solar cells. Our results indicate that this thermal evaporation technique is a promising approach to improve the large-scale fabrication of antimony chalcogenide solar cells.
关键词： Thermal evaporation,Sb2Se3,Hydrogen-sulfide,Large-scale,Post-annealing process
更新于2025-09-23 15:21:01
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Wetting-Layer-Free AlGaN Quantum Dots for Ultraviolet Emitters
摘要： We exhibit both experimentally and theoretically a novel growth mode for the epitaxy of AlGaN quantum dots (QD), where they are eventually produced without their usual surrounding wetting layer. If the generic evolution of QD is ruled by the elastic relaxation and capillary effects, evaporation occurs here on a time scale similar to that of growth. Using a dedicated surface diffusion model accounting for elasticity, wetting and anisotropy, we evidence numerically different kinetic regimes as a function of the evaporation flux, that rationalize the experimental outcome. The resulting QD are characterized by enhanced optical properties compared to the common QD with a wetting layer. These nanostructures are promising candidates for deep ultraviolet light emitting diodes.
关键词： epitaxy,ultra-violet emitters,evaporation,quantum dots,wetting-layer
更新于2025-09-23 15:21:01
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Commitment Between Roughness and Crystallite Size in the Vanadium Oxide Thin Film opto-electrochemical Properties
摘要： The V2O5 thin films has been widely studied because it has application as ionic host in electrochromic and lithium-ion batteries, two technologies that have an intimate connection with sustainability as substitutes for fossil energies and as agents for improving energy efficiency. In electrochromic technology, V2O5 is applied as a passive electrode due to its high transmittance and small contrast, and its reversibility on electrochemical reactions. To contribute to increase the optical and charge efficiency of V2O5 thin film passive electrodes, were investigated in this work the influence of the morphological properties, crystallite size and roughness, on the reversible specific charge capacity and the respective optical responses. The films morphological properties were modified by varying their thickness to the nanoscale. The films were deposited by thermal evaporation from powdered V2O5. The crystallite size and surface roughness were measured respectively by XRD and AFM. The results showed that the charge capacity is directly proportional to the surface roughness and inversely proportional to the crystallite size. The film optical contrast and the nominal transmittance shows to be improved according to their morphological properties. In conclusion, the V2O5 opto-electrochemical properties can be improved, increasing the efficiency on the light control processes.
关键词： Thermal evaporation,electrochromism,vanadium oxide,lithium intercalation
更新于2025-09-23 15:21:01
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Novel report on structural, optical and electrical investigation into brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate single crystal: a promising material for high-power laser, ultrahigh cooling, sensor and detector applications
摘要： A new brucinium 4-methyl-3-nitrobenzoate 0.5 hydrate (B4M3NB0.5H) NLO single crystal was harvested from saturated solution by solvent evaporation method. Crystal system and symmetric type of B4M3NB0.5H compound were analyzed by structure analysis. Linear optical parameters of title compound were discussed in detail by UV–visible analysis. Lifetime values of the molecule were quanti?ed by ?uorescence study, and it con?rms the good crystalline perfection of the grown crystal. The SHG ef?ciency is 5.11 times superior to the KDP material. By utilizing Nd:YAG laser as an input, SLDT measurement of the crystal was done. The grown crystal has good crystalline nature which is analyzed by HRXRD study. Dielectric behavior of B4M3NB0.5H crystal was discussed in detail. With the help of theoretical approach, few of the solid-state parameters were calculated and listed. Piezoelectric charge coef?cient and piezovoltage were calculated to be 4.5 p C/N and 0.0417 p V m/N, respectively. The TGA and DTA spectrum con?rms that the title compound is thermally stable up to 101 °C.
关键词： piezoelectric charge coefficient,brucinium 4-methyl-3-nitrobenzoate,fluorescence study,solvent evaporation method,SHG efficiency,HRXRD study,NLO single crystal,Nd:YAG laser,dielectric behavior,UV–visible analysis,TGA and DTA spectrum
更新于2025-09-23 15:21:01