Nanoparticle Thin Films Research Articles

Intensive study of coating multilayer TiO2 nanoparticles thin films used for optoelectronics devices

High-performance of TiO2 nanoparticles (NPs) thin films were synthesized using spin coating technique deposited on a glass substrate. The effect of the several layers of films which have formed is studied on the structure, morphology, surface, optical and electrical characteristics. From the analysis using X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), raman spectroscopy, ultraviolet–visible spectrophotometer and impedance spectroscopy the obtained results show that anatase crystalline is obtained after annealing at 400 °C from TiO2 (NPs) in powder form. The surface of samples is uniform and the rms roughness is dependent on the number of layers and varied within the range 25.40–43.81 nm. The optical bandgap energy is obtained in the 2.9–3.2 eV range of multilayer TiO2 (NPs) thin films. The electrical characteristic analyzed as a function of temperature and frequency demonstrated a semiconducting behavior, and showed a decreased of resistance with the increase of temperature. The obtained activation energy based on impedance analysis is about 0.7 eV. It is showed that TiO2 deposited on the SnO2 glass substrate has anatase crystalline structure and their optical bandgap energy is about 3.0 eV. Electrical analysis shows semiconductor behavior over the explored temperature range from 400 °C.

Energy storehouse and a remarkable photocatalyst: Al2S3/Cu2S/Ni17S18 thin film as supercapacitor electrode and pollutants degradation

ABSTRACT Fabrication of the tri metal sulphide Al2S3-Cu2S-Ni17S18 thin film was achieved by physical vapour deposition. The synthesised material was fully characterised by XRD, SEM, EDX, UV-visible spectrophotometer and FTIR. A nanoscale ranged 23.5 nm average crystallite size was obtained for the ternary metal sulphide. A motley of clustered morphological particles was observed by SEM with the confirmation of the desired metals through energy dispersive X-ray. Band gap energy possessed by the ternary metal sulphide was 2.5 eV. The remarkable energy storing capability of the electrode was investigated by cyclic voltammetry, which presented a supercapacitance of 595 F g−1 expressing the pertinence of the synthesised material. Cycling stability of the nanoparticle thin film was also observed through the voltammetric analysis. Furthermore, the environmental applicability of the thin film was investigated by the photocatalytic degradation of pollutants with an impressive degradation rate constant 3.61 × 10−2 min−1 achieved for pesticide.

Ag Reflectors: An Effective Approach to Improve Light Harvesting in Dye Sensitized Solar Cells

High-performing and commercially viable dye sensitized solar cells (DSSCs), operable under indirect sunlight illumination, exhibit great potential among current photovoltaic technologies, however, have smaller light absorption coefficients that hinder their usefulness. In this article, we have focussed on enhancing the light-harvesting of DSSCs by using silver nanoparticles thin films to improve the light absorption of N719 dye molecules loaded over the active layer of mesoporous TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (m-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). The Ag nanoparticles thin films acted as reflectors in the fabrication of DSSCs, which resulted in a power conversion efficiency of 6.65% compared to the 5.61% of the standard configuration cells. The effect is ascribed to the increased light absorption ability of DSSCs given the improved reflectivity of the counter electrode through Ag reflectors, resulting in the reabsorption of reflected light by the sensitized photoanodes. The results were further supported by the reduced resistances at different interfacial layers in the DSSCs, as measured by electrochemical impedance spectroscopy, thus indicating improved charge transfer kinetics. This article provides insight into the possibility of exploiting Ag nanoparticles in reflectors for improving light harvesting in the PV devices realm.

The Performance of V2O5:Ag Nanoparticles as Thin Film and Bulk Pellet Sensor for NO2 and NH3 Detection

A comparison of gas sensing performance of V2O5:Ag nanoparticles as thin film and as bulk pellet toward NO2 and NH3 is presented. V2O5:Ag nanoparticles thin films were deposited by vacuum thermal evaporation method on glass substrates while the pellets were prepared by powder technology. XRD patterns of thin film and pellet were polycrystalline with an orthorhombic structure. The value of average grain size is about 60 nm. The morphological properties of the samples have been distinguished by atomic force microscopy (AFM) and field effect scanning electron microscopy (FESEM) which indicated that the films showed homogeneous surfaces morphology and contained pores between the grains. Sensing results showed a various response to NO2 and NH3 gases. It was found that the sensitivity of thin films sensor is superior to that of the pellets sensor.

Optical response of plasmonic silver nanoparticles after treatment by a warm microwave plasma jet

This work investigates the effect of plasma treatment on the morphology and composition of 15 × 15 mm2 silver nanoparticle (70–80 nm) thin films. The silver nanoparticles are deposited onto thermal silica (SiO2/Si) substrates by spin-coating, then they are treated by an open-to-air microwave argon plasma jet characterized by a neutral gas temperature of 2200 ± 200 K. Scanning electron microscopy analysis reveals that the number of isolated nanoparticles in the film sample decreases after exposure to multiple jet passes, and that polygonal structures with sharp corners and edges are produced. Similar structures with much rounder edges are obtained after conventional thermal annealing at temperatures up to 1300 K. Based on localized surface plasmon resonance analysis in the range of 350–800 nm, the main extinction band of silver nanoparticles experiences a redshift after treatment with the plasma jet or with thermal annealing. Moreover, both treatments induce surface oxidation of the nanoparticles, as evidenced by x-ray photoelectron spectroscopy. However, only the plasma-exposed samples exhibit a significant rise in the surface-enhanced Raman scattering (SERS) signal of oxidized silver at 960 cm−1. 29 29 μm2 mappings of hyperspectral Raman IMAging (RIMA) and multivariate curve resolution analysis by log-likelihood maximization demonstrate that the SERS signal is controlled by large-scale micrometer domains that exhibit sharp corners and edges.

Third-order optical nonlinearity and multiferroicity of nanoparticles thin films of isovalent rare earth Y3+ ion substituted BiFeO3

Present work reveals the multiferroic and nonlinear optical properties of pristine and Yttrium (Y3+) substituted BiFeO3 nanoparticles synthesized by sol-gel technique, and fabricated thin films of the nanoparticles. The nanoparticles thin films were deposited on glass substrates with an average thickness of 85 nm by the thermal evaporation method in a high vacuum of 10−6 Torr. The structural and morphological studies were done by using XRD, Fullprof, XPS, AFM, FESEM and TEM with SAED. Further BET method was used to find out the surface area, pore size and pore volume of the nanoparticles. The multiferroic properties of Bi1-xYxFeO3 (x = 0.0, 0.5, 0.10, 0.15) have been investigated using VSM (magnetic) and P-E loop tracer (electrical). The doping of magnetic Y3+ions in host BiFeO3 nanoparticles modified and improved the optical, structural, multiferroic properties enormously. Linear optical properties were characterized by UV–Visible, Raman, and Photoluminescence. Third-order nonlinear absorption coefficient (β) and the imaginary part of third-order susceptibility (χi3) of Bi1-xYxFeO3 (x = 0.0, 0.5, 0.10, 0.15) have been investigated using a single beam Z-scan technique with a continuous wave (CW) diode laser of 520 nm wavelength. The films exhibit saturation absorption (SA) behavior and it increases on increasing the Yttrium (Y3+) substitution in BiFeO3. Thus, the NLO behavior of the films makes it an auspicious material for application in optoelectronic devices.

Flexible Organic Photodetectors with Mechanically Robust Zinc Oxide Nanoparticle Thin Films.

Zinc oxide nanoparticle (ZnO-NP) thin films have been intensively used as electron transport layers (ETLs) in organic optoelectronic devices, but their moderate mechanical flexibility hinders their application to flexible electronic devices. This study reveals that the multivalent interaction between ZnO-NPs and multicharged conjugated electrolytes, such as diphenylfluorene pyridinium bromide derivative (DFPBr-6), can significantly improve the mechanical flexibility of ZnO-NP thin films. Intermixing ZnO-NPs and DFPBr-6 facilitates the coordination between bromide anions (from the DFPBr-6) and zinc cations on ZnO-NP surfaces, forming Zn2+-Br- bonds. Different from a conventional electrolyte (e.g., KBr), DFPBr-6 with six pyridinium ionic side chains holds the Br--chelated ZnO-NPs adjacent to DFP+ through Zn2+-Br--N+ bonds. Consequently, ZnO-NP:DFPBr-6 thin films exhibit improved mechanical flexibility with a critical bending radius as low as 1.5 mm under tensile bending conditions. Flexible organic photodetectors with ZnO-NP:DFPBr-6 thin films as ETLs demonstrate reliable device performances with high R (0.34 A/W) and D* (3.03 × 1012 Jones) even after 1000 times repetitive bending at a bending radius of 4.0 mm, whereas devices with ZnO-NP and ZnO-NP:KBr ETLs yield >85% reduction in R and D* under the same bending condition.

Characterization of tin selenide nanoparticle films generating from plasma arc penetration of a temperature-varying field

Using the pulsed laser deposition (PLD) method, tin selenide (SnSe) nanoparticles thin films are created on quartz substrates, which are held at different penetration field temperatures Tp-f (Tp-f is the penetration field temperature to which the plasma arc is exposed) (300, 373, 473, and 573) K. X-ray powder diffraction (XRD) reveals a phase transformation from a hexagonal to an orthorhombic structure. The energy gap, which ranges from 1.748-3.15 eV with direct electronic transmission, is calculated using transmittance spectra. Particle size increases by Tp-f increases. Photoluminescence (PL) intensity and film thickness are inversely proportional to each other. Changing the ratio of the compositions provides an essential strategy for altering a material's melting point as well as its energy gap.

Printed Platinum Nanoparticle Thin-Film Structures for Use in Biology and Catalysis: Synthesis, Printing, and Application Demonstration.

This work describes the formulation of a stable platinum nanoparticle-based ink for drop-on-demand inkjet printing and fabrication of metallic platinum thin films. A highly conductive functional nanoink was formulated based on dodecanethiol platinum nanoparticles (3-5 nm) dispersed in a toluene-terpineol mixture with a loading of 15 wt %, compatible with inkjet printing. The reduced sintering temperatures (200 °C) make them interesting for integration in devices using flexible substrates and substrates that cannot tolerate high-temperature exposures. A resistive platinum heater was successfully printed as a demonstrator for integration of the platinum ink. The platinum nanoink developed herein will be, therefore, attractive for a range of applications in biology, chemistry, and printed electronics.

Slippery lubricant-infused silica nanoparticulate film processing for anti-biofouling applications.

Microbial biofilm build-up in water distribution systems can pose a risk to human health and pipe material integrity. The impact is more devastating in space stations and to astronauts due to the isolation from necessary replacement parts and medical resources. As a result, there is a need for coatings to be implemented onto the inner region of the pipe to minimize the adherence and growth of biofilms. Lubricant-infused surfaces has been one such interesting material for anti-biofouling applications in which their slippery property promotes repellence to many liquids and thus prevents bacterial adherence. Textured and porous films are suitable substrate candidates to infuse and contain the lubricant. However, there is little investigation in utilizing a nanoparticulate thin film as the substrate material for lubricant infusion. A nanoparticulate film has high porosity within the structure which can promote greater lubricant infusion and retention. The implementation as a thin film structure aids to reduce material consumption and cost. In our study, we utilized a well-studied nanoporous thin film fabricated via layer-by-layer assembly of polycations and colloid silica and then calcination for greater stability. The film was further functionalized to promote fluorinated groups and improve affinity with a fluorinated lubricant. The pristine nanoporous film was characterized to determine its morphology, thickness, wettability, and porosity. The lubricant-infused film was then tested for its lubricant layer stability upon various washing conditions and its performance against bacterial biofilm adherence as a result of its slippery property. Overall, the modified silica nanoparticulate thin film demonstrated potential as a base substrate for lubricant-infused surface fabrication that repelled against ambient aqueous solvents and as an anti-biofouling coating that demonstrated low biofilm coverage and colony forming unit values. Further optimization to improve lubricant retention or incorporation of a secondary function can aid in developing better coatings for biofilm mitigation.

Low-temperature in situ preparation of Eu3+/Tb3+-doped CaMoO4/SrMoO4 nanoparticle thin films and their application in anti-counterfeiting.

Rare earth-doped metal oxide thin films exhibit remarkable potential for application in anti-counterfeiting, owing to their exceptional fluorescent properties. However, the existing fabrication techniques for these rare earth-doped luminescent thin films are predominantly complex and necessitate high-temperature conditions. In light of this issue, we present a low-temperature method for in situ fabrication of luminescent Ca1-xMoO4:Eux3+ and Sr1-xMoO4:Tbx3+ nanocrystal thin films by a solution deposition process. The developed method has the advantages of simple operation, rapid and low-temperature synthesis. The optimal chemical compositions of molybdate-based luminescent films are Ca0.90MoO4:Eu0.103+ and Sr0.90MoO4:Tb0.103+. Moreover, we evaluate the practical feasibility of luminescent nanoparticle films in the field of anti-counterfeiting by combining the unique fluorescent properties of rare earth ions and designing customized fluorescent patterns.

Effect of gold on photo luminescence properties of Cadmium Sulphide thin films deposited by pulsed laser deposition

Cadmium Sulphide (CdS) on gold (Au) nanoparticle thin films were deposited by pulsed laser deposition (PLD) on sapphire and Silicon (Si) substrates. The films were analyzed by X-ray photo electron spectroscopy (XPS) to determine the binding energy of the constituent elements, atomic force microscopy (AFM) for surface morphology, X-ray diffraction (XRD) for crystal structure, photo luminescence (PL) and UV–VIS measurements for optical properties. The results of XPS analysis and spectroscopic ellipsometric characterization revealed the formation of CdS films. The films surface shows uniform smooth topography and having Hexagongal phase crystalline structure. The optical absorption spectra of CdS films deposited at room temperature (RT) showed absorption edge at around 580 nm which blue-shifted at high deposition temperature of 300 °C. The band edge photoluminescence of CdS films observed at 590 nm was enhanced with Au nanoparticle films present as the bottom of the layer attributed to the plasmonic related optical coupling between two materials. However, when the nanoparticles were deposited on top layer the luminescence was found to be quenched due to the internal absorption of the Au films due to plasmon resonance. The results of the study reveal that the optimum controlled deposition of Au nanoparticles with CdS thin films will be useful for fabrication of efficient opto-electronic devices.

Effect of the effective refractive index on the radiative decay rate in nanoparticle thin films.

In this work, we theoretically and experimentally study the influence of the optical environment on the radiative decay rate of rare-earth transitions in luminescent nanoparticles forming a thin film. We use electric dipole sources in finite-difference time-domain simulations to analyze the effect of modifying the effective refractive index of transparent layers made of phosphor nanocrystals doped with rare earth cations, and propose a correction to previously reported analytical models for calculating the radiative decay rate. Our predictions are tested against an experimental realization of such luminescent films, in which we manage to vary the effective refractive index in a gradual and controllable manner. Our model accurately accounts for the measurements attained, allows us to discriminate the radiative and non-radiative contributions to the time-resolved photoluminescence, and provides a way to rationally tune the spontaneous decay rate and hence the photoluminescence quantum yield in an ensemble of luminescent nanoparticles.

Realizing high performance gas filters through nano-particle deposition.

We have studied the separation of a mixture of hydrogen and methane in equal proportions, using a thin film comprised of 10 layers of nanoparticles deposited layer-wise using our "two-point sticking algorithm" which simulates controlled agglomeration of such nanoparticles. We simulate the process of gas separation using LAMMPS. We have studied the scenario where nanoparticles act like hard spheres, maintaining their shape and size, similar to what has been demonstrated by experiments involving self-assembled nanoparticle thin films. We consider the pressure dependence of the results by working at 3 different initial pressures, 0.1 × P0, 0.5 × P0 and P0, where P0 is the atmospheric pressure. Three different diameters of the nanoparticles, namely 3 nm, 6 nm and 9 nm, are considered, and therefore the overall thickness of the membranes considered ranges from 30 nm to 90 nm. We obtained perm-selectivity values that are significantly higher than the Robeson line for hydrogen-methane gas separation, indicating the novelty and therefore the significant applications of this work. We find that while the permeance of hydrogen remains more or less steady with a ten-fold increase of pressure, the corresponding fall in methane's permeance is very sharp. The fall in methane's permeance with increasing pressure is more pronounced the smaller the nanoparticles of the membrane being used. This results in an even higher selectivity at higher pressure for smaller nanoparticle based membranes.

Nanoparticle thin film solar cells: illuminating the path to sustainable energy

Nanoparticle thin film solar cells: illuminating the path to sustainable energy

Enhancement of upconversion photoluminescence in phosphor nanoparticle thin films using metallic nanoantennas fabricated by colloidal lithography.

Lanthanide-doped upconversion nanoparticles (UCNPs), as multifunctional light sources, are finding utility in diverse applications ranging from biotechnology to light harvesting. However, the main challenge in realizing their full potential lies in achieving bright and efficient photon upconversion (UC). In this study, we present a novel approach to fabricate an array of gold nanoantennas arranged in a hexagonal lattice using a simple and inexpensive colloidal lithography technique, and demonstrate a significant enhancement of UC photoluminescence (UCPL) by up to 35-fold through plasmon-enhanced photoexcitation and emission. To elucidate the underlying physical mechanisms responsible for the observed UCPL enhancement, we provide a comprehensive theoretical and experimental characterization, including a detailed photophysical description and numerical simulations of the spatial electric field distribution. Our results shed light on the fundamental principles governing the enhanced UCNPs and pave the way for their potential applications in photonic devices.

Light-enhanced electrical behavior of a Au/Al-doped ZnO/p-Si/Al heterostructure: insights from impedance and current-voltage analysis.

In this study, we meticulously deposited an Al-doped ZnO nanoparticle thin film on a p-type silicon substrate using the precise sputtering method. We conducted a comprehensive exploration of the film's structure, morphology, and optical properties. X-ray diffraction (XRD) confirmed its polycrystalline wurtzite configuration with a dominant (002) orientation. High-resolution scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed a uniformly textured surface adorned with densely packed nanoparticles. Regarding optical properties, the Al-doped ZnO thin film exhibited exceptional transmittance exceeding 80% across visible and near-infrared spectra. Moving on to electrical characteristics, we assessed the Au/Al-doped ZnO/p-Si/Al heterostructure under dark and illuminated conditions. Through current-voltage (I-V) and impedance measurements, we observed significant improvements in conductivity and performance under illumination. Notably, there was an increase in current conduction and a reduction in impedance, highlighting the advantages of illumination. Collectively, these findings emphasize the promising potential of the Au/Al-doped ZnO/p-Si/Al heterostructure, particularly in the realms of optoelectronic devices and photovoltaics. With its ability to efficiently mobilize charges and adeptly assimilate light, this heterostructure stands as a frontrunner for transformative applications in these technologically vital domains.

Electrophoretic deposited gold nanoparticle thin film on silver substrate

AbstractEffects of the deposition time and voltage on the characteristics of gold nanoparticles (NPs) thin films, prepared by the electrophoretic deposition (EPD) method on the silver substrate, were investigated experimentally. Au NPs were synthesised using the pulsed laser ablation method in distilled water. The suspended solution of the gold NPs was used as the electrolyte of EPD. An irradiation was carried out by the fundamental wavelength of a Q‐switched NdYAG laser at 1064 nm and 7 ns pulse width. The electrophoretic deposition apparatus consisted of two 2 × 2 cm pieces of silver plates as the electrodes. They were immersed in parallel with a 7 mm gap in the gold NP suspension. Five samples of gold NP thin films were prepared at different deposition times and applied voltages. Results show that the roughness, thickness and surface quality of EPD prepared thin films can be strongly controlled by the deposition time and applied voltage. The thickness of deposited films was dependent on the voltage of deposition in which their roughness was increased with increasing the deposition time. Furthermore, the reflection of deposited films was affected by the surface roughness.

Novel nanocomposite thin films for efficient degradation of Rhodamine B and Rhodamine 6G under visible light irradiation: Reaction Mechanism and Pathway studies

The present investigation aims to synthesize the novel nanocomposite thin film and utilize the material to remove emerging dyes efficiently (i.e., Rhodamine B (R-B) and Rhodamine 6G (R-6G)), in an aqueous solution using LED visible light and UV-A light. A facile synthetic route was adopted to obtain the TiO&lt;sub&gt;2&lt;/sub&gt;-supported bentonite and &lt;i&gt;in situ&lt;/i&gt; decorated with Au nanoparticles (NPs) thin film. The advanced analytical techniques characterizes the materials. The laboratory scale reactor was utilized for efficient degradation of R-B and R-6G using thin film catalysts. The percentage removal of R-B was 54.13% (visible light) and 76.26% (UV-A light) and the R-6G, was removed 60.37% (visible light) and 84.68% (UV-A light) at the initial pollutant concentration of 0.5 mg/L and at pH 6.0 using the thin film photocatalyst. The parametric studies demonstrated the insights of degradation mechanisms in photocatalytic operations. A significant mineralization of these dyes is achieved, and the repeated use in reactor operations indicated the catalysts

Design of a Novel Nanosensors Based on Green Synthesized CoFe2O4/Ca-Alginate Nanocomposite-Coated QCM for Rapid Detection of Pb(II) Ions.

Pb(II) is a significant contaminant that is known to have negative effects on both humans and animals. Recent industrial operations have exacerbated these consequences, and their release of several contaminants, including lead ions, has drawn attention to the potential effects on human health. Therefore, there is a lot of interest in the rapid, accurate, and selective detection of lead ions in various environmental samples. Sensors-based nanomaterials are a significant class among the many tools and methods developed and applied for such purposes. Therefore, a novel green synthesized cobalt ferrite (CoFe2O4) nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite was designed and successfully synthesized for the fabrication of nanoparticles and nanocomposite-coated quartz crystal microbalance (QCM) nanosensors to detect the low concentrations of Pb(II) ions in the aqueous solutions at different temperatures. The structural and morphological properties of synthesized nanoparticles and nanocomposite were characterized using different tools such as X-ray diffraction (XRD), N2 adsorption–desorption isotherm, dynamic light scattering (DLS), zeta potential analyzer (ζ-potential), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The QCM results revealed that the green synthesized CoFe2O4 nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite-coated QCM nanosensors exhibited high sensitivity, stability, and rapid detection of Pb(II) ions in the aqueous solutions at different temperature. The lowest detection limit for Pb(II) ions in the aqueous solutions could reach 125 ng, which resulted in a frequency shift of 27.49 ± 0.81, 23.63 ± 0.90, and 19.57 ± 0.86 Hz (Δf) for the QCM detector coated with green synthesized CoFe2O4 nanoparticles thin films, and 25.85 ± 0.85, 33.87 ± 0.73, and 6.87 ± 0.08 Hz (Δf) for the QCM detector coated with CoFe2O4/Ca-Alg nanocomposite thin films in a real-time of about 11, 13, and 13 min at 25 °C, 35 °C, and 45 °C, respectively. In addition, the resonance frequency change results showed the superiority of functionalized CoFe2O4/Ca-alginate nanocomposite coated QCM nanosensor over CoFe2O4 nanoparticles towards Pb(II) ions detecting, which attributed to the beneficial properties of alginate biopolymer.