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Heterogeneous Growth of Continuous ZIF-8 Films on Low-Temperature Amorphous Silicon
摘要： Thin amorphous silicon films, deposited at low temperature by Inductively Coupled Plasma Chemical Vapor Deposition, have, for the first time, been employed as substrate for ZIF-8 growth. In order to investigate the role of the surface chemistry on the nucleation process, films have also been grown on other silicon-based substrates such as H-terminated Si(100), SiO2 and quartz. Film preparation was carried out at room temperature using a mixed Zn nitrate and imidazole solution in methanol or ethanol. Using methanol, continuous ZIF-8 films were obtained on amorphous Si and H-terminated Si(100), while less homogeneous films were formed on the other surfaces. In ethanol, slower growth rates occurred and thinner films, compared to the ones in methanol, were obtained. These slower rates highlight the different effects of the four surfaces on the growth process. These differences have been related to the silanol density of the surfaces and to the Lewis basic strength which affect imidazole moiety deprotonation. H-terminated Si(100) and amorphous Si turned out to be the most reactive surfaces, whereas on quartz and, especially, on SiO2 reactivity was much lower. Experimental results have been validated by the DFT modelling of the proton exchange, which takes place between the imidazole group and the surface. Finally, the VOCs adsorption capability of ZIF-8 films grown on amorphous silicon has been evaluated through temperature desorption experiments.
关键词： a-Si layer,ZIF-8 coating,growth mechanisms,VOCs adsorption,surface chemistry
更新于2025-11-21 11:03:25
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One-step growth of reduced graphene oxide on arbitrary substrates
摘要： Reduced graphene oxide (rGO) has inherited the outstanding electronic, optical, thermal and mechanical properties of graphene to a large extent, while maintaining sufficient chemically active sites. Therefore, it has attracted a great deal of research attention in the fields of energy storage, electronics, photonics, catalysis, environmental engineering, etc. Currently, the most popular way to prepare rGO is to reduce graphene oxide, which is obtained by modified Hummer methods using tedious treatments in a harsh environment, to rGO flakes. Industrial applications demand advanced preparation methods that can mass produce highly uniform rGO sheets on arbitrary substrates. In this work, a one-step growth process is introduced that utilizes cellulose acetate as a precursor, without any catalysts, to produce uniform ultrathin rGO films on various substrates and free-standing rGO powders. Systematic spectroscopic and microscopic studies on the resulting rGO are performed. Prototypes of electronic and optoelectronic devices, such as field effect transistors (FETs), photodetectors, and humidity sensors, are fabricated and tested, demonstrating the intriguing applications of our rGO materials across a wide range of fields.
关键词： electronic devices,reduced graphene oxide,one-step growth,cellulose acetate,optoelectronic devices
更新于2025-11-21 11:03:25
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Hollow hierarchical structure Co0.85Se as efficient electrocatalyst for the triiodide reduction in dye-sensitized solar cells
摘要： The exploration of nonprecious metal-based electrocatalysts with high efficiency for the triiodide reduction is critical for the practical applications of the dye-sensitized solar cells. Herein, we develop a facile one-step hydrothermal method to synthesize hollow hierarchical structure Co0.85Se. Under the methanol-water reaction system, the product named as hollow hierarchical structure Co0.85Se-M has the largest specific surface area (215.36 m2 g?1) and the best crystallinity than other products obtained from other alcohol-water reaction systems. When this electrocatalyst is applied as a counter electrode for the dye-sensitized solar cells, it exhibits a small peak-to-peak separation (Epp, 97 mV) for the reduction of I3?/I? redox couple. It is found that the catalytic activity of Co0.85Se is closely dependent on the crystallinity. Moreover, the reactivity pathway is identified by density functional theory, which confirms that triiodide is reduced to iodide ion on Co0.85Se with a smaller energy barrier (～0.65 eV) than on Pt (～1.18 eV). Both experimental and theoretical results demonstrate Co0.85Se-M as an ideal counter electrode material for the dye-sensitized solar cells with a higher power conversion efficiency (8.76%) than Pt counter electrode (7.20%).
关键词： Dye-sensitized solar cells,Hollow hierarchical structure,Cobalt selenides,Electrocatalytic activity,Triiodide reduction
更新于2025-11-21 11:03:13
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Investigation of valence plasmon excitations in GMZO thin film and their suitability for plasmon-enhanced buffer-less solar cells
摘要： The approach of eliminating buffer layer in conjunction with plasmon-enhanced transparent conduction oxide (TCO) layer is an attractive methodology to realize low-cost ultrathin buffer-less solar cells (SCs) by introducing plasmon-enhanced absorption and reduced fabrication steps. Here, we report a novel method to generate wide-band sputter-stimulated plasmonic feature in Ga-doped-MgZnO (GMZO) thin-films, which are observed due to the different metallic and metal-oxide nanoclusters formation. Through an extensive analysis of photoelectron spectroscopy, spectroscopic ellipsometry, and field-emission scanning electron microscope measurements the evaluation of plasmonic features and correlation of them with various nanoclusters inside GMZO thin-film is performed. Additionally, the suitability and expected performance of plasmon-enhanced GMZO thin-film based buffer-less SCs are probed through; 1) band-offset analysis at the plasmon enhanced-GMZO/CIGSe heterojunction; 2) simulation studies to analyze the effect of conduction band-offset (CBO) on the performance of the buffer-less SCs; 3) predicting the performance of the buffer-less SC using the parameters of GMZO thin-films with varying CBO, and 4) envisaging the concept of ultrathin buffer-less SC with calculated CBO and absorber layer thickness (300 nm) for ultrathin SCs. Moreover, at the experimentally calculated band-offset with ultrathin absorber layer thickness (300 nm), theoretically calculated buffer-less SC performance parameters estimated to be open-circuit voltage (Voc): 0.75 V, short-circuit current density (Jsc): 17.29 mA/cm2, fill-factor (FF): 80.5%, and efficiency (Eff): 10.46%.
关键词： Ultrathin solar cells,UPS,CIGSe,Plasmons
更新于2025-11-21 11:03:13
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Investigation of valence electron excitation and plasmonic enhancement in sputter grown NMZO thin films: For energy harvesting applications
摘要： We report a novel approach of sputter-stimulated plasmonic generation in Na-doped MgZnO (NMZO) thin films. Sputtering of material during film growth by utilizing secondary direct-coupled ion-source present in dual-ion beam sputtering system leads to the generation of nanoclusters of its constituent elements due to different sputtering-out rates of various elements present in the films. The authentication of plasmonic generation in NMZO is conducted as follows a) identification of plasmonic signature in electron energy loss spectra obtained by ultraviolet photoelectron spectroscopy measurement, b) valence bulk, valence surface, and particle plasmon resonance energy calculations are performed, and each plasmon peak is indexed with corresponding plasmon energy peak of different nanoclusters, and c) spectroscopic ellipsometric measurement is deployed to verify plasmonic behavior by investigating different optical properties. Additionally, incorporation of the plasmonic feature along with alkali metals plays a crucial role in the improvement of the performance of solar cells. Therefore, plasmon enhanced NMZO as a backscattering layer in between CIGSe/back contact is probed to ascertain the additional benefits of 1) Na incorporation into the absorber layer as a result of the Na diffusion from the NMZO layer, and 2) improvement in the morphology of the CIGSe thin film with the incorporation of NMZO layer in between the back-contact and CIGSe. The diffusion of Na into the absorber layer is probed by deploying secondary ion mass spectroscopy measurements, and improvement in the morphology of CIGSe with the incorporation of NMZO layer between the back-contact/absorber is investigated using field-emission scanning electron microscope analysis.
关键词： UPS,NMZO,Ultrathin solar cells,Plasmons,Sputtered
更新于2025-11-21 11:03:13
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Photo-Modification of Melanin by a Mid-Infrared Free-Electron Laser
摘要： Melanin is rigidly constructed by several nitrogen-containing aromatic rings, and its excess accumulation in skin tissue is closely associated with melanosis. Although visible lasers (wavelength: 600–1000 nm) are conventionally used for the photo-thermolysis of melanocyte, several pigmented nevi are difficult to be treated. Here, we propose an alternate method for targeting the molecular structure of melanin using an infrared free electron laser (FEL) tuned to 5.8 μm that corresponds to the stretching vibrational mode of carboxylate group. A drastic morphological change on the black-colored surface of melanin powder were observed after the pulse irradiation with a power of 500 mJ/cm2, and the minimum irradiation time for damage to the morphology was 1.4 seconds. Analyses by mass spectroscopy, infrared spectroscopy, and 13C-nuclear magnetic resonance implied that a pyrrole group was removed by the FEL irradiation. In addition, the FEL irradiation dispersed almost all of the melanoma cells from a culture solution without any influence on other ingredients in the medium, and one-cell analysis by infrared microscopy showed that the structure of melanoma could be substantially damaged by the irradiation. This study proposes the potency of intense mid-infrared laser as novel alternative way to reduce melanin.
关键词： Infrared free electron laser,Melanoma,Vibrational mode,Melanin,Photo-modification
更新于2025-11-21 11:03:13
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A Light-Driven Micromotor with Complex Motion Behaviors for Controlled Release
摘要： Micromotor that exhibits various movement behaviors has attracted more attention in recent years. However, most researchers focus on its motion behavior and few have studied the fluid flow surrounding it. In this work, a novel micromotor with both controlled motion behavior and surrounding fluid flow, which is driven by near-infrared (NIR) light based on the unique Marangoni effect caused by the light irradiation of its constituent, i.e., polypyrrole (PPy), is reported. Interestingly, these motion behaviors and the surrounding fluid flow can be easily switched by adjusting the incident angle of the NIR laser. This unique property may have potentials in different fields. Among others, its application in remotely controlled targeted delivery and release is demonstrated.
关键词： micromotors,cargo release,light-driven,polypyrrole
更新于2025-11-21 11:03:13
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Highly flexible self-powered photodetectors based on core–shell Sb/CdS nanowires
摘要： Flexible photodetectors have great applications in flexible image sensors, wearable electronics and smart robots. In this work, we reported the fabrication of highly flexible self-powered photodetectors with core-shell Sb/CdS nanowires as the sensing materials. The fabricated device exhibited high Ion/Ioff ratio of 3.54×103 under zero bias, fast speed of photoresponse and great stability. An open-circuit voltage of 0.35 V was generated due to the presence of CdS and CdSb interfaces within the core-shell nanowires. Besides, the photocurrent of the flexible device is nearly invariable at various bending angles and even after thousands of bending cycles, demonstrating the excellent flexibility and bending stability. The results indicated that the self-powered photodetectors are promising candidates for future passive optoelectronic devices.
关键词： core-shell Sb/CdS nanowires,optoelectronic devices,self-powered,flexible photodetectors
更新于2025-11-21 11:03:13
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Non‐Stoichiometry Induced Switching Behavior of Ferroelectric Photovoltaic Effect in BaTiO <sub/>3</sub> Ceramics
摘要： Ferroelectric photovoltaic (FPV) effect has been studied among a series of non-stoichiometric BaTiO3 (Ba/Ti ? 0.92–1.05) ceramic chips prepared by tape casting method. The FPV performance increases abruptly when the Ba/Ti molar ratio deviates from the stoichiometry within 1%. Meanwhile, a photocurrent direction switching behavior is observed between Ti-excess and Ba-excess samples. The TEM analysis shows their significant difference in grain-boundary (GB), where abnormal GB with a width of 10–15 nm is observed in Ba-excess sample. The photocurrent switching phenomenon is described to the competition between the asymmetrical Schottky barriers induced PV effect and intrinsic FPV effect. Widen GB in Ba-excess BaTiO3 ceramics restrains the intrinsic FPV effect and results in the switching behavior. This study offers direct evidence of the vital role of GB in FPV effect and may promote the development of photovoltaic devices.
关键词： ferroelectric photovoltaic,barium titanate,non-stoichiometry,switching behavior
更新于2025-11-21 11:03:13
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Crystallographically oriented porous ZnO nanostructures with visible-blind photoresponse: controlling the growth and optical properties
摘要： We have grown catalyst-free crystallographically oriented porous ZnO nanostructures by pulsed laser deposition (PLD) method. The deposition was performed in two stages for each sample. In the first stage, self-seeding of ZnO was performed on the quartz substrate, and the angle of deposition (seeding-angle) was varied. Thus, the growth of seeds is different here. In the second stage, the deposition was performed at a glancing angle (at 85?) for the fixed duration of time to grow the nanostructures. These PLD-grown nanostructures acquire highly oriented wurtzite structure. We find that the seeding-angle during the first stage is the determining deposition parameter which influences the growth and other properties of these nanostructures in a controllable manner. The variation in seeding-angle systematically tunes the crystallographic orientation and porosity, which in turn influences the visible-blindness and ultraviolet (UV) photoresponse of these nanonetworks. Here we report the growth of completely defect-free crystallographically oriented nanostructures with necessary porosity for application in visible-blind UV photodetection.
关键词： Crystalline ZnO,catalyst-free ZnO,glancing angle deposition (GLAD),seeding,pulsed laser deposition (PLD),nanostructures
更新于2025-11-21 11:03:13