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- 摘要
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- 实验方案
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High Operation Stability and Different Sensing Mechanisms in Graphene Oxide Gel Photodetectors Utilizing a Thin Polymeric Layer
摘要： We report a significant improvement in the operational stability and photosensitivity of an interdigitated photodetector using a hybrid sensing material based on a reduced graphene oxide gel (femtogel) and poly methyl methacrylate (PMMA). By coating the reduced graphene oxide photodetector with a protective layer of PMMA, a noticeable current stability is achieved, either during a sweep or fixed voltage, compared to an unprotected photodetector. A bolometric-effect sensing mechanism was observed in the unprotected photodetector, whereas the hybrid PMMA/femtogel photodetector displayed a photovoltaic-effect sensing mechanism. This change in the sensing mechanism of the graphene-based device, as a result of encapsulating the sensing area using a polymeric thin layer, is reported for the first time. Moreover, a higher and reliable sensitivity to the low-power illumination source was observed in the hybrid PMMA/femtogel photodetector. This study provides an avenue for engineering the performance and reliability of graphene oxide photodetectors that operate in an ambient environment in order to solve the current bottleneck issue, resulting from lack of reliability, in commercializing these material.
关键词： Bolometric effect,Sensing mechanism,PMMA,Photodetector,Graphene oxide,Graphene gel
更新于2025-09-23 15:19:57
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Determination of the Chronological Order of a Laser Printing and Gel Pen Writing Without any Crossing Strokes
摘要： Laser printers and writing instruments are being exploited by the forgers to produce fabricated documents. They often produce such documents by appending genuine signature on a blank sheet and later printing on it. Often these fabricated documents do not contain intersection of strokes and may pose a difficulty to forensic document examiners in analyzing cases related to such documents. Keeping in mind the limited research work done on nonintersecting strokes, the present study has been conducted with an aim to determine the sequence of nonintersecting strokes of gel pens and laser printers. Three hundred samples of nonintersecting strokes of gel pen ink and laser printing were prepared. Of these 300, 150 had laser-printed text below the gel pen strokes and the remaining 150 were prepared with gel pen stokes below the laser-printed text. The samples have been analyzed using Nikon SMZ 800N stereomicroscope. Three micro-conformation features, that is, pattern of toner distribution, ink distribution, and fiber distribution have been observed in the samples. The results demonstrate the successful establishment of sequence of nonintersecting strokes in case of gel pen and laser-printed documents by the determination of micro-conformation features.
关键词： nonintersecting strokes,laser printer,questioned document examination,sequence of nonintersecting strokes,stereomicroscope,gel pen,micro-conformation features
更新于2025-09-23 15:19:57
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Thin silica-based microsheets with controlled geometry
摘要： A high demand for materials with defined geometry and size is required in a wide range of fields. Inorganic compounds, especially silica-based, arise as a cheap source and chemically flexible for the purpose. Silica display unique properties, like easy functionalization and good optical to manipulate. In this work, we developed a method to create thin silica microsheets with defined size and high-fidelity shape using superhydrophobic-hydrophilic microarrays. These microstructures were produced through sol-gel process using biomimetic superhydrophobic surfaces decorated with wettable spots. The results confirm the manufacture of porous silica microstructures with defined design (squares and circles) and thickness around 7 μm. The methodology applied in this work enables the high throughput fabrication of shaped silica materials in a single step, unlocking an extensive number of applications in areas that require miniaturization, like microelectronics or in fields like sensing and biomedicine.
关键词： Silica microsheets,High-fidelity shape,Inorganic materials,High throughput,Sol-gel process
更新于2025-09-23 15:19:57
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Plasmonic gel nanocomposites for detection of high energy electrons
摘要： Radiation therapy is a common treatment modality employed in the treatment of cancer. High energy photons are the primary source of radiation but when administered, they leave an exit dose resulting in radiation damage to the adjacent healthy tissues. To overcome this, high energy electrons are employed in cases of skin cancer to minimize radiation induced toxicity. Despite these advances, measurement of delivered radiation remains a challenge due to limitations with existing dosimeters including labor intensive fabrication, complex read-out techniques and post-irradiation instability. To overcome these limitations, we have developed a novel colorimetric plasmonic gel nanocomposite for the detection of therapeutic levels of radiation delivered in electron beam therapy. The plasmonic nanocomposite consists of an agarose gel matrix encapsulating precursor gold ions, which are reduced to gold nanoparticles as a result of exposure to high energy electrons. The formation of gold nanoparticles renders a change in color to the agarose matrix, resulting in the formation of plasmonic gel nanocomposites. The intensity of the color formed exhibits a linear relation with the delivered electron dose, which can be quantified using absorbance spectroscopy. The plasmonic gel nanocomposites were able to detect doses employed in fractionated electron therapy, including in an anthropomorphic phantom used for planning radiation treatments in the clinic. Furthermore, the use of glutathione as a quenching agent facilitated qualitative and quantitative spatial mapping of the delivered dose. Our results indicate that the ease of fabrication, simplicity of detection and quantification using absorbance spectroscopy, determination of spatial dose profiles, and relatively low cost make the plasmonic gel nanocomposite technology attractive for detecting electron doses in the clinic.
关键词： gold nanoparticles,Plasmonic gel nanocomposites,radiation therapy,high energy electrons,absorbance spectroscopy
更新于2025-09-23 15:19:57
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Poly(ethylene glycol)a??poly(propylene glycol)a??poly(ethylene glycol) and polyvinylidene fluoride blend doped with oxydianiline-based thiourea derivatives as a novel and modest gel electrolyte system for dye-sensitized solar cell applications
摘要： Unique symmetrical thiourea derivatives with an oxydianiline core were synthesized using cost-effective and simple methods. A new gel electrolyte system was prepared using these thiourea additives along with a highly conductive PEG–PPG–PEG block copolymer, PVDF, and an iodide/triiodide redox couple. The PEG units present in the electrolyte are well-known for their intense segmental motion of ions, which can degrade the recombination rate and favour the charge transfer. The thiourea additives interacted well with the redox couple to limit iodine sublimation and their adsorption induced a negative potential shift for TiO2. The highest efficiency attained by utilizing such gel polymer electrolytes was 5.75%, especially with 1,10-(oxybis(4,1-phenylene))bis(3-(6-methylpyridin-2-yl) thiourea) (OPPT), under an irradiation of 100 mW cm?2. The electrochemical impedance spectroscopy, UV-vis absorption spectroscopy, differential scanning calorimetry, and FTIR spectroscopy data of such gel polymer electrolytes favoured the PCE order of the additives used in DSSCs. The improvement in the DSSC performance with symmetrical thioureas having electron-rich atoms was practically attributed to the reduction of back electron transfer, dye regeneration, and hole transport.
关键词： Poly(ethylene glycol),poly(ethylene glycol),dye-sensitized solar cell,polyvinylidene fluoride,poly(propylene glycol),oxydianiline-based thiourea derivatives,gel electrolyte system
更新于2025-09-23 15:19:57
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Enhancement of power conversion efficiency of Al/ZnO/p-Si/Al heterojunction solar cell by modifying morphology of ZnO nanostructure
摘要： This paper proposes a cost-effective sol–gel method for synthesis of ZnO nanostructure to make Al/ZnO/p-Si/Al heterojunction solar cell. Here, crystalline ZnO nanostructure was grown on p-silicon and annealed at 300 °C, 400 °C and 500 °C for application in heterojunction solar cell. The optimum temperature for obtaining uniform crystalline nanostructure was 500 °C, as confirmed from XRD and SEM imaging. As investigated by UV–Vis spectroscopy, the ZnO nanostructure layer exhibited high transmittance in the visible spectrum and has a direct band gap of 3.26–3.28 eV. The power conversion efficiency of Al/ZnO/p-Si/Al solar cell is enhanced from 1.06 to 2.22% due to increase in surface area of ZnO by formation of crystalline nanostructure due to increase of annealing temperature. The optimum value of short-circuit current (Isc) and open-circuit voltage (Voc) was measured using current–voltage (I–V) under AM 1.5 illuminations and found to be 9.97 mA and 460 mV, respectively.
关键词： Power conversion efficiency,Sol–gel method,Annealing temperature,Heterojunction solar cell,ZnO nanostructure
更新于2025-09-23 15:19:57
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A sola??gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (IIa??VI) metal oxides
摘要： A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make manganese oxide (Mn3O4), copper oxide (CuO), and magnesium hydroxide (Mg(OH)2) nanostructures with size- and shape-controlled morphologies. Nanostructures of Mn3O4 with either hexagonal, irregular particle, or ribbon shape morphologies with an average diameter ranged from 100 to 200 nm have been prepared in four di?erent solvent types. In all morphologies of Mn3O4, the experimental XRD patterns have indexed the nanocrystal unit cell structure to triclinic. The hexagonal nanoparticles of Mn3O4 exhibit high mesoporocity with a BET surface area of 91.68 m2 g?1 and BJH desorption average pore diameter of ～28 nm. In the preparation of CuO nanostructures, highly nanoporous thin sheets have been produced in water and water/toluene solvent systems. The simulated XRD pattern matches the experimental XRD patterns of CuO nanostructures and indexes the nanocrystal unit cell structure to monoclinic. With the smallest desorption total pore volume of 0.09 cm3 g?1, CuO nanosheets have yielded the lowest BET surface area of 18.31 m2 g?1 and a BHJ desorption average pore diameter of ～16 nm. The sol of magnesium hydroxide nanocrystals produces highly nanoporous hexagonal nanoplates in water and water/toluene solvent systems. The wide angle powder XRD patterns show well-de?ned Bragg's peaks, indexing to a hexagonal unit cell structure. The hexagonal plates show a signi?cantly high BET surface area (72.31 m2 g?1), which is slightly lower than the surface area of Mn3O4 hexagonal nanoparticles. The non-template driven sol–gel synthesis process demonstrated herein provides a facile method to prepare highly mesoporous and nanoporous nanostructures of binary (II–VI) metal oxides and their hydroxide derivatives, enabling potential nanostructure platforms with high activities and selectivities for catalysis applications.
关键词： catalysis applications,size and shape-controlled morphologies,mesoporous nanostructures,binary (II–VI) metal oxides,sol–gel synthesis
更新于2025-09-23 15:19:57
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Structural and luminescence studies of Sm3+:CaLa4Si3O13 phosphors: An orange-emitting component for WLEDs application
摘要： With the help of the conventional sol-gel process, six different concentrations of CaLa4-xSi3O13:xSm3+ (0.005≤x≤0.09) phosphors were fabricated. For all samples, by XRD crystal structure and luminescence features have been examined. Based on the diffuse reflectance spectrum, for CaLa3.91Si3O13:0.09Sm3+ phosphor, both direct and indirect optical band gaps have been computed. Following measured PLE and PL spectra, we found that samples can be pumped efficiently by n-UV or blue LED chips for obtaining an intense orange emission at 598 nm (4G5/2→6H7/2) upon 403 nm (6H5/2→4F7/2) excitation. CIE color chromaticity coordinates (x, y) for both CaLa4Si3O13:0.005 and 0.09 Sm3+ phosphors are computed following their corresponding emission spectra. Under 365 nm UV lamp, CaLa4Si3O13:0.09 Sm3+ sample exhibits a bright orange color emission. In this work, it was found that the CaLa4Si3O13:0.09 Sm3+ phosphor possesses potentiality for YAG:Ce3+ phosphor color rendering index (CRI) improvement in WLEDs, excited by the blue LED chips.
关键词： CaLa4Si3O13,XRD,Sm3+ ion,CIE,Photoluminescence,Sol-gel
更新于2025-09-23 15:19:57
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Enhanced efficiency of quantum dot light-emitting diode by sol-gel derived Zn1-xMgxO electron transport layer
摘要： In this study, sol-gel derived Zn1-xMgxO (ZMO) is proposed as an electron transport layer (ETL) for solution-processed quantum-dot light-emitting diodes (QLEDs). It is demonstrated that the increase of Mg content in Zn1-xMgxO films from 0% to 20% causes a dramatic suppression of electron current, which is attributed to the lifting of conduction band minimum and reduction of electron mobility. As a result of Mg-doping, the charge carrier balance might be achieved in the QLED with the Zn0.85Mg0.15O layer resulting in maximum external quantum efficiency of 5.74% and current efficiency of 18 cd·A-1, which are over 3-fold higher than in the case of the device with ZnO layer. Improved device performance is further explained by reduced exciton quenching at QDs/ZMO interface, which is confirmed by time-resolved PL experiments. Obtained results indicate that sol-gel derived ZMO is a promising candidate for ETL in quantum-dot based optoelectronic devices.
关键词： quantum dot,doped zinc oxide,sol-gel process,light-emitting diode,electron transport layer
更新于2025-09-23 15:19:57
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Influence of the modification of annealing parameters on solution-processed metal oxide ETL buffer layers, and a comparative study of spin-coated and thermally evaporated MoOx HTL for use in an inverted polymer solar cell
摘要： Transparent metal oxide thin films were synthesized on indium tin oxide (ITO) substrates via the sol-gel spin coating method using various precursor solutions. The types of metal oxides investigated were zinc oxide (ZnO), titanium dioxide (TiO2) and molybdenum oxide (MoOx) whose purpose was to serve as buffer layers in organic solar cells. ZnO and TiO2 layers were to serve as electron transport layers (ETL), and the MoOx layer served as a hole transport layer (HTL). Compared to conventional ordering, in this set-up, the sequence of the buffer layers is inverted to improve the stability of the polymer solar cells. The annealing temperature during the preparation of the ETL metal oxide layers was varied in order to investigate the effect on the morphological properties of the thin films. The HTL layer was both spin-coated and thermally evaporated and the results were compared. The surface morphology and elemental analysis of the prepared samples were studied using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) capability. The optical properties were investigated by UV–Vis spectroscopy and it was found that the metal oxide layers have high optical transparency in the visible range, as required. The crystal structures of the prepared metal oxides were investigated by X-ray diffraction (XRD). A comparative study on the effect of the ETLs individually in solar cells was done by incorporating them individually with active layers of blends of poly (3-hexylthiophene) (P3HT), as electron donor and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron acceptor respectively. The device performance was subsequently measured and compared.
关键词： Metal oxide,Sol-gel,Buffer layers,Spin coating,Solar cell,Organic
更新于2025-09-23 15:19:57