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Enhanced Ultraviolet Emission from Hydrothermally Grown ZnO Nano-Grass on Si Substrate
摘要： Highly crystalline one-dimensional zinc oxide (ZnO) nano-grass was grown on silicon (Si) substrate by a modified hydrothermal method. A predominantly c-oriented ZnO nano-grass with an average diameter of 40–60 nm and length of 1.5–2.0 lm was obtained. From the photoluminescence (PL) measurement, we observed a defect-free, intense ultraviolet emission of as-grown ZnO nano-grass, confirming the absence of singly ionized oxygen vacancies. The absence of green deep-level emission in the PL spectrum further implies a high crystallinity of as-grown ZnO nano-grass. The high-quality ZnO nano-grass has potential applications in single nanowire-based light-emitting diodes, solar cells, themoresistive sensing, photocatalysis, ultraviolet photodetectors, optical switches, waveguides and nano-lasers.
关键词： photoluminescence,ZnO nanowires,annealing process,ultraviolet emission,hydrothermal method
更新于2025-09-23 15:22:29
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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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A Thermally Induced Perovskite Crystal Control Strategy for Efficient and Photostable Widea??Bandgap Perovskite Solar Cells
摘要： Wide-bandgap perovskite solar cells (WBG PSCs) have gained attention as promising tandem partners for silicon solar cells due to their complementary absorption, superb open-circuit voltage, and easy solution process. Recently, both their performance and stability have been improved by compositional-engineering or defect-passivation strategies, due to modulation of perovskite crystal size and reduction of crystal defects. In this work, we report a thermally induced phase control (TIPC) strategy, which enables efficient and photostable WBG PSCs without any compositional engineering by exploring a thermal annealing process window of WBG perovskite films for the annealing temperature and time range of 100-175°C and 3-60 minutes, respectively. Within this window, we found a key annealing regime that produces preferred crystal orientations of lead iodide and the WBG perovskite, suppressing phase segregation and reducing charge recombination in the perovskites. The WBG PSC (composition of FA0.75MA0.15Cs0.1PbI2Br and Eg of 1.73 eV) optimized by TIPC exhibited an excellent power conversion efficiency (PCE) of 18.60% and improved operational stability, maintaining >90% of the maximum PCE (during maximum power point tracking) without encapsulation after 12-hour operation under AM 1.5G irradiation in ambient air conditions and after 500-hour operation under white LED irradiation (100 mW cm-2) in inert N2 gas conditions.
关键词： wide-band gap perovskite,thermal annealing process,operational stability,perovskite solar cells,invariant bandgap
更新于2025-09-23 15:21:01
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Novel ethanol vapor annealing treatment of SnO2 quantum dots film for highly efficient planar heterojunction perovskite solar cells
摘要： As a promising electron transport layer (ETL) material, tin oxide (SnO2) has been widely used for high-quality perovskite solar cells (PSCs). To further raise power conversion efficiency (PCE) of the PSCs, it is critical to improve the performance of SnO2 film. Herein, a facile method is proposed to tailor the properties of SnO2 ETL by treating it with ethanol vapor during the annealing process. With such treatment, the conductivity and electron mobility of SnO2 film are improved. More impressively, the absorption peak in intensity of the perovskite film deposited on the ethanol vapor-treated SnO2 (E: SO) shows an increase, and the defect states are also effectively passivated. Thus, the VOC and FF of the devices based on the E: SO are greatly improved. Finally, the device achieves a champion PCE of 17.66%, which is superior to the control device of 16.62%. The results demonstrate that ethanol vapor annealing treatment is an effective method for improving the performance of photovoltaic devices based on SnO2 ETL.
关键词： annealing process,ethanol vapor treatment,tin oxide quantum dot,Perovskite solar cell
更新于2025-09-23 15:19:57
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A novel quartz-crystal microbalance humidity sensor based on solution-processible indium oxide quantum dots
摘要： Having a large surface area, like the quantum con?nement e?ect also caused by the nano-level size of quantum dots (QDs), creates fantastic potential for humidity sensing. A high concentration of surface adsorption sites initiates an increased response. Porosity between QDs allows fast water vapor penetration and out?ow. Here, a quartz-crystal microbalance (QCM) humidity sensor was prepared using indium oxide (In2O3) QDs, synthesized via a solvothermal method. After the In2O3 QDs were directly spin-coated onto the QCM, an annealing process removed organic long chains and exposed more moisture adsorption sites on the surfaces of the QDs. The annealed QCM humidity sensor exhibited high sensitivity (56.3 Hz per %RH at 86.3% RH), with a fast response/recovery time (14 s/16 s). Long carbon chains were broken down, and hydrogen-bonded hydroxyl groups were chemisorbed to the QDs. The chemical reaction was reduced by these chemisorbed hydrogen-bonded hydroxyl groups. Mass change was mostly caused by fast multilayer physisorption. Thus, the transducer can e?ectively and precisely monitor the moisture from a person's breath. In2O3 QD-modi?ed QCM sensors demonstrate promising humidity-sensing applications in daily life.
关键词： indium oxide quantum dots,annealing process,solvothermal method,humidity sensor,quartz-crystal microbalance
更新于2025-09-16 10:30:52
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Fields of application for laser beam polishing of optical glasses
摘要： Conventional manufacturing of freeform optics is expensive and elaborate. The laser beam as a polishing tool offers the possibility to produce optical surfaces fast and effective. The aim of new research on laser beam polishing of optical glasses is to achieve a polished surface finish irrespective of the surface geometrics. The carbon dioxide laser is applied to process pre-machined specimen with different roughness’s. During the polishing process an infrared camera is necessary to monitor the temperature on the surface. An annealing process reduces the process-related tensions. In addition, the cleaning process is investigated to minimize the surface damages. To characterize the surface topographic a white-light interferometer and a stylus instrument are applied. Laser beam polishing of minerals glasses such as N-BK7?, BF33? and fused silica enables surface roughness of less than Ra < 5 nm by form maintenance. By means of self-design setup, the adaption of laser beam polishing on glass cylinders, lenses or freeform is possible. As a result a parallel laser beam with a diameter of 12.65 mm is applied to process tilted surfaces up to 45°. With a laser parameter modulation, the angle-dependent absorption depending on the intensity of the laser radiation is considered.
关键词： white-light interferometer,surface finish,optical glasses,annealing process,cleaning process,infrared camera,carbon dioxide laser,laser beam polishing,stylus instrument
更新于2025-09-11 14:15:04
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Micro-nano scale imaging and the effect of annealing on the perpendicular structure of electrical-induced VO2 phase transition
摘要： It was research hotspot that how to lower the threshold switching voltage (Vth), especially for the perpendicular structure of electrical-induced VO2 insulator-metal phase transition (MIT). This structure can reduce the Vth to the orders of 10-1 V. In micro-nano scale, combined with results of resistance change versus temperature, X-ray photoelectron spectroscopy measurements and conductive atomic force microscope, we had confirmed that V3+ was an important factor for electrical-induced VO2 thin MIT. On the one hand, joule heating produced by conductive V3+ region induced the surrounding VO2 region phase transition. On the other hand, with the annealing time increased from 0 min to 2 min at 470℃ in H2/N2 mixture gases, V3+ contents increased, thin film surface conductive areas increased, thin film resistance decreased, and finally resulted in threshold switching voltage decreased. Our experimental results were consistent with theory analysis. However, when the annealing time was too long (≥3 min), VO2 thin film threshold switching behavior disappeared, and current was linearly increased with voltage.
关键词： Perpendicular structure of electrical-induced VO2 MIT,Annealing process,Micro-nano scale current mapping,perpendicular VO2 thin film structure,threshold switching voltage
更新于2025-09-09 09:28:46