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Three-dimensional Nanoscale Mapping of Porosity in Solution-Processed ITO Multilayer Thin Films for Patternable Transparent Electrodes
摘要： Indium tin oxide (ITO) films constitute components of many layered heterostructures used for emergent technologies beyond conventional optoelectronics. Compositional and morphological changes have a direct impact on the device’s performance. Hence control over the morphology with advanced multimodal characterization approaches are required to evaluate the devices. Herein multilayer ITO films deposited by spin coating were quantified in nanoscale detail in three dimensions by combining results from depth-sensitive neutron reflectometry (NR), non-contact topographic AFM images and cross-sectional SEM images. Films with different number of deposited layers were visually transparent even though the topmost layer was as high as 60% porous, with porosity gradually decreasing as the number of the underneath sublayers increased. Surface and interfacial roughness through the total film and individual layer thickness were obtained. NR data also furnished quantitative depth information on the films chemical composition and layer-by-layer bulk density, which has never been obtained before, providing a way to monitor and ultimately control the sheet resistivity via the pore network. When the same formulation is used for inkjet printing patterns, the larger pores disappear and the optical properties are improved to >90% transmittance at all visible wavelengths. All 5L films achieved sheet resistivities as low as 10-2 ?-cm and can therefore be used as patternable transparent electrodes for many devices including liquid crystal displays.
关键词： thin multilayer film,neutron reflectometry,depth density distribution,neutron absorption reflectometry,Indium tin oxide,porosity,structure chemical depth profile,off-specular neutron scattering,layer by layer deposition
更新于2025-11-19 16:56:35
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Lossy Mode Resonance Generation by Graphene Oxide Coatings onto Cladding-Removed Multimode Optical Fiber
摘要： In this work, we have studied the suitability of graphene oxide-based thin films to be not only excellent sensitive coatings but also lossy mode resonance (LMR)-generating materials. Thin films of graphene oxide (GO) and polyethylenimine (PEI) fabricated by means of layer-by-layer assembly were selected in this study. Two optical fiber devices with 8 and 20 bilayers of the LMR-generating coating were fabricated and characterized as refractometers. Both devices show no hysteresis and high sensitivity, improving previously reported values. This research opens very promising and exciting possibilities in the field of optical fiber sensors based on LMR, strategically including specific recognition groups to the device surface to exploit this high sensitivity for monitoring a range of target analytes. The carboxylate functional groups at the edges of the GO sheets should provide excellent attachment sites for the required coupling chemistry to realize such devices.
关键词： optical fiber sensor,thin films,Dip-assisted layer by layer,lossy mode resonance,refractometer,graphene oxide
更新于2025-11-14 15:19:41
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Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications
摘要： With reference of our previous report (Appl. Surf. Sci. 2018, ASAP), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (4000C – 4500C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using x-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.
关键词： XPS Spectroscopy,Layer-by-layer MoS2:GO composite thin films,I-V curve
更新于2025-10-22 19:40:53
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Inorganic Protection of Polymer Nanocapsules: A Strategy to Improve the Efficiency of Encapsulated Optically Active Molecules
摘要： We demonstrate that the efficiency under ambient conditions of optically active molecules encapsulated in polymer nanocapsules can be significantly improved by depositing an inorganic layer onto the polymeric shell. A triplet-triplet annihilation upconversion (TTA-UC) system consisting of a porphyrin derivative and perylene is used as a representative case. Different inorganic materials are deposited on the surface of functionalized polymer nanocapsules synthesized by free-radical polymerization in miniemulsion. First, a silicate clay with formula [Si8(Mg5.45Li0.4)O20(OH)4]Na0.7 is deposited on the surface of positively charged polystyrene nanocapsules via layer-by-layer deposition. Second, controlled in situ mineralization of hydroxyapatite and cerium(IV) oxide are carried out on the surface of negatively charged polystyrene nanocapsules. In both cases the inorganic materials on the nanocapsule surface act as a scavenger and avoid the entry of oxygen from the external environment. By avoiding the entry of oxygen, the photo-oxidation process of perylene molecules is avoided within the system, and an increase in the TTA-UC properties occurs.
关键词： upconversion,nanocapsule,crystallization,layer-by-layer,miniemulsion polymerization
更新于2025-09-23 15:23:52
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Photoactive Gel for Assisted Cleaning during Olive Mill Wastewater Membrane Microfiltration
摘要： A photoactive gel has been fabricated on the surface of polyethylene membranes for enhancing the fouling resistance during olive mill wastewater treatment. Light and pH responsive materials have been introduced in the membrane surface through the build up of a layer-by-layer pattern, which is formed by photocatalytic nanoparticles and ionic polyelectrolytes. The best working conditions to contrast foulants adsorption have been explored and identified. Repulsive interfacial forces and assisted transfer of foulants to catalytic sites have been envisaged as crucial factors for contrasting the decline of the flux during microfiltration. Tests in submerged configuration have been implemented for six continuous hours under irradiation at two different pH conditions. As a result, a worthy efficiency of the photoactive gel has been reached when suitable chemical microenvironments have been generated along the shell side of the membranes. No additional chemical reagents or expensive back-flushing procedures have been necessary to further clean the membranes; rather, fast and reversible pH switches have been enough to remove residues, thereby preserving the integrity of the layer-by-layer (LBL) complex onto the membrane surface.
关键词： submerged microfiltration,layer-by-layer,titanium oxide nanoparticles,water treatment,self-cleaning
更新于2025-09-23 15:23:52
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Continuous Photocatalysis Based on Layer-by-layer Assembly of Separation-free TiO?/Reduced Graphene Oxide Film Catalysts with Increased Charge Transfer and Active-site
摘要： Although photodegradation is the most widely studied method for the purification of water, the challenges for the post-separation of catalysts from water prevent the technique from practical applications. In this study, separation-free TiO2/reduced graphene oxide (rGO) multilayer films were first prepared through layer-by-layer (LbL) assembly of TiO2 and graphene oxide (GO) on quartz slides, followed by a reduction of the assembled GO to rGO. For a proof-of-concept demonstration of novel continuous photocatalysis with potential for scale-up production, these quartz slides with TiO2/rGO film catalysts were further assembled into slide arrays in a home-made rectangular quartz reactor and a model pollutant Rhodamine B (RhB) solution was circularly pumped over the slide surface under UV irradiation. It was found that the as-prepared TiO2/rGO film catalysts show excellent enhanced continuous photocatalytic activity, with a photodegradation rate constant of 2.6 × 10-2 min?1 exceeding the corresponding TiO2/GO and TiO2 (TiO2/PSS) samples by a factor of 11.3 and 13, respectively. The enhanced performance is attributed to the formation of Ti-O-C bonds in film catalysts bridging TiO2 and rGO to enable efficient charge separation and transfer, the Ti-O-C bond bridged electron transfer leading to increase in ·O2- active sites on the rGO surface, and the porous-like multilayer structure. The recycling experiments showed the film catalysts are stable and could be reused with the same efficiency for at least 8 cycles.
关键词： layer-by-layer,continuous photocatalysis,separation free,graphene,film
更新于2025-09-23 15:23:52
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Simultaneous optimization of transmittance and resistivity for γ-CuI thin films via an iodination method at mild reaction condition
摘要： In p-type γ-CuI thin films synthesized by the iodination of Cu layers with iodine vapor, a frosted-glass-like appearance with a rough surface is usually obtained, which makes it difficult to apply the γ-CuI films to transparent electronics. This paper proposes an innovative method for the preparation of highly transparent p-type γ-CuI films. A chemical reaction between Cu thin films and iodine vapor, combined with the layer-by-layer process at a temperature between room temperature and 120°C are found to result in highly transparent polycrystalline γ-CuI films. The root-mean-square roughness values of the γ-CuI films prepared by this method are 8.5–21.2 nm, which are smaller than those for the γ- CuI films synthesized by the conventional method. The microstructure and optoelectronic properties of the γ-CuI thin films are sensitive to the temperature of iodine vapor. A high transmittance (80%) of the film obtained at an iodine vapor temperature of 80°C has a low resistivity of 5×10?2 Ω cm and high mobility of 8.7 cm2/Vs. Moreover, a boosted figure of merit is realized due to the simultaneously low resistivity and high transparency: its value jumps from ～488 to ～1630 MΩ-1.
关键词： figure of merit,low resistivity,high transmittance,layer by layer method
更新于2025-09-23 15:23:52
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Layer-by-layer self-assembly of polyaniline nanofibers/TiO2 nanotubes heterojunction thin film for ammonia detection at room temperature
摘要： In this paper, for the first time, polyaniline nanofibers/TiO2 nanotubes (PANI/TiO2) heterojunction thin film has been prepared on Pt interdigital electrodes by layer-by-layer self-assembly method and applied in room temperature NH3 detection. It is found that the optimal self-assembly layer number is three (PANI/TiO2-3) compared to one layer (PANI/TiO2-1) and five layers (PANI/TiO2-5). The PANI/TiO2-3 thin film sensor possesses superior response characteristics compared with our other PANI based sensors, including higher response value (336%@5 ppm NH3), acceptable response/recovery time (110 s/1086 s@5 ppm NH3), low detection limit (0.5 ppm), and remarkable selectivity. The enhanced gas sensing performances could be ascribed to the tremendous variation of the carrier concentration caused by the p-n junctions as well as the increased specific surface area and pore volume. This work not only offers a superb strategy to fabricate heterojunction thin film but also accelerates the development of room-temperature operable NH3 sensors.
关键词： Ammonia detection,Layer-by-layer self-assembly,Polyaniline/TiO2 heterojunction,Thin film,Room temperature operation
更新于2025-09-23 15:23:52
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Layer-by-layer Modification of Magnetic Graphene Oxide by Chitosan and Sodium Alginate with Enhanced Dispersibility for Targeted Drug Delivery and Photothermal Therapy
摘要： In this work, graphene oxide nanosheets loaded by magnetic iron oxide nanoparticles (mGO) was synthesized and the technique of layer-by-layer (LbL) self-assembly was utilized in the successful production of chitosan/ sodium alginate functionalized mGO naocomposites for use in targeted anti-cancer drug delivery and photothermal therapy. The mGO-CS/SA nanocomposites had a diameter of ~0.5 μm and a thickness of 40-60 nm with superparamagnetic behavior. The modified nanocomposites exhibited a decrease in agglomeration and an increase in stability in biological solution following stability tests. Meanwhile, the nonspecific protein adsorption was strongly suppressed after the modification. The mGO-CS/SA nanocomposites were loaded with doxorubicin hydrochloride (DOX) via π- π stacking and electrostatic attraction with a high drug loading amount (121%, w/w). The DOX-loaded nanocomposites (mGO-CS/SA-DOX) showed improvements in function including enhanced dispersion and noticeable pH-sensitive drug release behavior. Cellular studies denoted magnetically targeted cellular uptake characteristics and excellent photothermal effect of mGO-CS/SA, as well as concentration-dependent cytotoxicity of mGO-CS/SA-DOX. Therefore the functionalization of mGO using chitosan and sodium alginate would be beneficial in biomedical applications.
关键词： magnetic nanocomposite,Layer-by-layer,Graphene oxide,photothermal therapy,drug delivery
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