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Synthesis, characterization, optical and electrochemical band gaps of green poly(azomethine-ester)s containing oxalyl and succinyl units
摘要： A new series of poly(azomethine-ester)s (PAZ-E)s with different (turning ortho, meta and para) positions were synthesized by condensation polymerization. The chemical structure of polymers was veri?ed by 1H-NMR, 13C-NMR, FTIR and UV–Vis measurements. Electrochemical characteristics of the corresponding polymers were obtained with cyclic voltammetric (CV) analysis. Thermal characteristics of the obtained polymers were analysed by TG-DTA, DMA and DSC measurements. The ?rst degradation temperature values of PAZ-E compounds were found between 198 and 250?C from TGA measurements. Photophysical characteristics of the obtained polymers were explained with photoluminescence (PL) spectroscopy. Molecular weight distributions of (PAZ-E)s were obtained by gel permeation chromatographic (GPC) analysis. Two- and three-dimensional (2D and 3D) properties and images of the synthesized (PAZ-E)s were analysed by SEM and AFM surface analysis techniques, respectively. Electrochemical band gap (E g) values of (PAZ-E)s P-9, P-10, P-11, P-12, P-13 and P-14 were calculated as 2.58, 2.14, 1.90, 2.06, 1.89 and 1.69 eV, respectively. The E g values of the (PAZ-E)s were found to be quite low.
关键词： surface morphologies,Poly(azomethine-ester),electrochemical properties,photophysical behaviour,schiff base,thermal degradation
更新于2025-11-14 15:26:12
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A micro-structural corrosion mechanism on the thermal degradation of BaMgAl10O17: Eu2+ phosphor
摘要： The thermal degradation is a vital issue that restricting luminous efficiency and service life of BaMgAl10O17: Eu2+phosphor for chromogenic and illuminating fields. The effects of heat-treatment temperature on the luminescence properties and micro-structure of BAM were researched to accurately elucidate the thermal degradation mechanism. Some pieces of evidence for micro-structural corrosion were detected according to the results of PL, TL, XPS and IR. With the heat-treatment temperature increasing, a decrease of blue-emitting intensity and new red-emitting peaks revealed thermal degradation and activator oxidation. The XPS results showed the surface chemical composition changes and the micro-structure adjustment. The defects elimination detected by TL could be responsible for this micro-structural corrosion. IR results further confirmed the changes on bond forms. These were direct evidence and specific forms for the micro-structural corrosion due to the thermal degradation. Based on the relationship between micro-structural corrosion and luminescence properties, a micro-structural corrosion mechanism was given for the thermal degradation of BAM phosphor. The thermal degradation was caused in parallel by the micro-structure corrosion and the activated ion (Eu2+) oxidation.
关键词： Micro-structural corrosion,Thermal degradation mechanism,BaMgAl10O17:Eu2+,Heat-treatment
更新于2025-09-23 15:22:29
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Thermally Stable, Efficient, Vapor Deposited Inorganic Perovskite Solar Cells
摘要： We report on thermally stable inorganic mixed halide perovskite solar cells deposited using a vapor deposition technique with no loss in device performance at 200 °C for 72 hours. X-ray diffraction analysis confirms no compositional degradation of the perovskite layer up to 200 °C anneals. We use a layer-by-layer vapor deposition technique with thin layers (several nm) of PbI2 and CsBr precursors to fabricate inorganic mixed halide perovskite solar cells with a photoconversion efficiency of 11.8%. We study the effect of several key parameters of the perovskite fabrication process that control the intermixing of the perovskite layer and their effect on device efficiency and hysteresis. The thermal stability of the perovskite material and its energy band gap of 1.87eV makes it appropriate for use in tandem junction cells for use in real-life environments with high solar illuminance where the ambient temperatures exceed 55 °C in the summer, and silicon cell module temperatures approach 86 °C.
关键词： Thermal Stability,inorganic perovskite solar cells,vacuum deposition,mixed halide perovskites,layer-by-layer deposition,thermal degradation
更新于2025-09-23 15:21:01
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Thermal Degradation Related to the PEDOT:PSS Hole Transport Layer and Back Electrode of the Flexible Inverted Organic Photovoltaic Module
摘要： The hole transport layer (HTL) and back electrode play a significant role in the stability of the flexible organic photovoltaic (OPV) module. In particular, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), a widely used hole transport material, is known to be associated with many degrading factors in the OPV field. This study highlights the impact of the PEDOT:PSS layer on thermal stability using a thermal accelerating test of flexible OPV modules with inverted structures of indium tin oxide/ZnO/photoactive layer/PEDOT:PSS/Ag. The results confirm that thermal degradation of the OPV devices depends on heat temperature, in which the OPV performance degrades by a notable decrease in the open-circuit voltage (Voc) as the temperature increases from 65 °C to 85 °C. Moreover, the stability of the Voc is enhanced when the PEDOT:PSS is thicker and contains polar solvent DMSO as an additive, suggesting that the thermal degradation can correlate with the properties of the PEDOT:PSS layer. In addition, microscope images of the active layers show that the surface damage is attributed to a residual solvent of printed Ag electrode, thereby resulting in a thermally-induced drop in the short circuit current density (Jsc). More detailed descriptions are presented in this paper, and the results are expected to offer comprehensive understanding of the thermal degradation mechanism of OPV module.
关键词： flexible OPV modules,PEDOT:PSS,hole transport layer,organic photovoltaics,thermal degradation
更新于2025-09-19 17:13:59
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Determination of sensitivity and thermal efficiency in laser assisted metal-plastic joining by numerical simulation
摘要： Laser-assisted joining of plastics and metals requires the formation of a melting layer in the thermoplastic material, which enables the wetting and the penetration of the metal surface. In this paper, a generally valid description of the melting layer is given based on material-specific temperatures and numerical simulation. Furthermore, the sensitivity of the melting layer to process parameters, material properties and geometrical parameters is provided. Based on these results, the thermal efficiency of the process was examined depending the major factors metal thickness and absorbed laser beam power.
关键词： thermal degradation,laser welding,LAMP,metal-plastic hybrid,thermal joining,hybrid joints,numerical simulation
更新于2025-09-12 10:27:22
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - An impact of thermal electron energy on the field-electron emission from nanosized silicon tips
摘要： Thermal effects associated with the thermal energy of electrons play an important role in the process of field emission. To estimate the contribution of these effects, a self-consistent numerical calculation of the temperature of the semiconductor emitter, heated by the field-emission current, was carried out. It was experimentally obtained that the melting of the silicon field emitter occurs at currents less than 1 μA, for which the calculated temperature of the silicon tip varies only up to 420 K and does not exceed the melting point of Si. For this reason, we suppose that this effect can be caused by the sputtering of the anode material by hot field-emitted electrons that collect a high power density (~300 W/cm2 at 1 μA) on the anode surface. It also can lead to the possible generation of self-sustained plasma in the space gap between anode and cathode. The considered thermal phenomena should be taken into account during the development and predictive modelling of vacuum nanoelectronic devices.
关键词： vacuum nanoelectronics,field-electron emission,emission current,nanoscale emitter,thermal degradation,thermal effects
更新于2025-09-10 09:29:36
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Generating highly specific spectra and identifying thermal decomposition products via Gas Chromatography / Vacuum Ultraviolet Spectroscopy (GC/VUV): Application to nitrate ester explosives
摘要： Gas chromatography/mass spectrometry (GC/MS) is a "workhorse" instrument for chemical analysis, but it can be limited in its ability to differentiate structurally similar compounds. The coupling of GC to vacuum ultraviolet (VUV) spectroscopy is a recently developed technique with the potential for increased detection specificity. To date, GC/VUV has been demonstrated in the analysis of volatile organic compounds, petroleum products, aroma compounds, pharmaceuticals, illegal drugs, and lipids. This paper is the first to report on the utility of GC/VUV for explosives analysis in general, and the first to report on thermal degradation within the VUV cell and its analytical utility. The general figures of merit and performance of GC/VUV were evaluated with authentic standards of nitrate ester explosives (e.g., nitroglycerine (NG), ethylene glycol dinitrate (EGDN), pentaerythritol tetranitrate (PETN), and erythritol tetranitrate (ETN)). In addition, the explosive analytes were thermally degraded in the VUV cell, yielding reproducible, complex and characteristic mixtures of gas phase products (e.g., nitric oxide, carbon monoxide, and formaldehyde). The relative amounts of the degradation products were estimated via spectral subtraction of library spectra. Lastly, GC/VUV was used to analyze milligram quantities of intact and burned samples of double-base smokeless powders containing nitroglycerine, diphenylamine, ethyl centralite, and dibutylphthalate.
关键词： Thermal degradation,Nitrate ester explosives,Vacuum ultraviolet spectroscopy,Gas chromatography
更新于2025-09-04 15:30:14