Search Results (165)

Three zinc(II) complexes based on 1-phenyl-3-methyl-4-acyl-5-pyrazolone were synthesized and characterized by elemental analysis, by X-ray crystallography and spectroscopy (UV-vis, fluorescence and IR). Crystallographic studies reveal that the complexes have a mononuclear structure in the solid state; however, intermolecular interactions combine the complexes into a 1D polymer chain. The complexes exhibit weak luminescence in the polycrystalline state and moderate emission in solutions and thin amorphous films. Thin films of the studied compounds were deposited on a glass substrate using thermal vacuum spraying, spin coating, and Langmuir-Blodgett technology and were studied using atomic force microscopy (AFM), X-ray spectroscopy, and fluorescence spectroscopy. Full article

In the present work, thin TiO₂ films were obtained by the sol–gel spin-coating method on glass and ITO-covered glass substrates. The crystallization evolution of the thin films was studied by the X-ray Diffraction (XRD) technique. The results indicate that the films’ crystalline structure was greatly affected by substrate type. X-ray photoelectron spectroscopy (XPS) revealed the chemical states of the TiO₂ films and proved the formation of TiO₂ on ITO substrates. Field Emission Scanning Electron Microscopy (FESEM) showed that the TiO₂ films deposited on the ITO glass possessed a uniform and homogeneous surface morphology. The influence of optical properties (transmittance, reflectance, and optical band gap) on substrate type, the number of layers and annealing temperatures was determined. Spectroscopic data confirmed high transparency of the TiO₂ films obtained on ITO substrates as the transmittance in the visible spectral range was close to 85%. The obtained results reveal that thin TiO₂ films on ITO substrates can be an excellent candidate for photovoltaic and optoelectronic applications. Full article

The precise control of optical and dielectric properties of semiconductor quantum-dot-based thin films remains a critical challenge for advanced optoelectronic applications. In this respect, (3-mercaptopropyl)trimethoxysilane (MPS)-capped CdS quantum dot thin films were prepared with MPS:Cd molar ratios of 0.25, 0.50, 1.00, and 2.00 to investigate the role of MPS content in tuning their optical and dielectric properties. The colloidal quantum dot solutions were deposited onto glass substrates by spin coating and subsequently annealed in air at 350 °C. Optical analyses showed that increasing MPS content enhanced film transmittance, whereas the refractive index, extinction coefficient, dielectric loss tangent, and optical conductivity decreased. At 550 nm, the refractive index decreased from 2.12 to 1.61, while the optical conductivity decreased from 6861 to 644 S m⁻¹ as the MPS ratio increased from 0.25 to 2.00. The Urbach energy exhibited a non-monotonic variation, reaching a maximum value of 415 meV at MPS:Cd = 0.50 and a minimum value of 193 meV at MPS:Cd = 2.00. Wemple–DiDomenico analysis revealed that the single-oscillator energy increased systematically with increasing MPS ratio, and the $E_0/E_{1S-1S}$ ratios remained within a narrow range of 1.32–1.46 throughout the MPS:Cd series. The analysis further revealed that the dispersion energy, static refractive index, infinite-wavelength dielectric constant, and linear susceptibility decreased with increasing MPS molar ratio. The estimated third-order nonlinear optical susceptibility and nonlinear refractive index also decreased with MPS content. Full article

The properties of solution-derived nickel oxide (NiO) thin films are strongly influenced by precursor chemistry and post-deposition thermal treatment. In this work, NiO thin films were deposited on indium tin oxide (ITO)-coated glass substrates by chemical solution deposition using a spin-coating process. A 0.6 M nickel acetylacetonate-derived precursor solution prepared in a methanol–propionic acid solvent system was used as the starting solution. The films were thermally treated at 600 °C under continuous oxygen flow, with annealing holding times of 2, 4, and 6 h, to evaluate the effect of thermal-treatment duration on phase formation, surface morphology, and electrochemical redox behavior. Thermal and infrared analyses confirmed precursor decomposition and the formation of nickel–oxygen bonding after thermal conversion. X-ray diffraction confirmed the formation of single-phase cubic NiO at all holding times, while quantitative peak analysis indicated a modest increase in crystallite size from 12.4 to 13.9 nm with prolonged annealing. Atomic force microscopy revealed continuous and homogeneous film surfaces, with low root-mean-square roughness values in the range of 2.5–2.7 nm. Cyclic voltammetry in a LiClO₄/propylene carbonate electrolyte showed a reversible redox response associated with the Ni²⁺/Ni³⁺ transition, accompanied by visible switching between bleached and colored states. The results indicate that annealing holding time affects the structural and morphological characteristics of spin-coated NiO thin films, while the electrochemical measurements confirm reversible redox activity in the investigated sample. These findings provide a processing-oriented basis for evaluating thermal-treatment conditions in solution-derived NiO films intended for electrochemical and optical modulation applications. Full article

In this study, the effect of Ti content on the electrochemical behavior and passive film growth mechanism of Ni₅₀Nb_50−xTi_x (x = 10, 15, and 20 at.%) metallic glasses produced via melt spinning was investigated. Structural characterization via X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the fully glassy nature and chemical homogeneity of all alloys. Electrochemical performance was evaluated in a 3.5 wt.% NaCl solution using potentiodynamic and potentiostatic polarization, as well as electrochemical impedance spectroscopy (EIS). The results showed that increasing Ti content improves corrosion resistance by reducing corrosion and passive current densities and increasing charge-transfer resistance. The Ni₅₀Nb₃₀Ti₂₀ alloy exhibited the best electrochemical performance, associated with the formation of a more stable and protective passive film. The passive film growth mechanism was analyzed using the High-Field Model (HFM). A linear relationship between inverse capacitance and anodic potential confirmed that ionic transport through the oxide layer governs passive film growth. The calculated electric field strength decreased systematically with increasing Ti content, suggesting the formation of passive films with lower defect density and enhanced barrier properties. These results demonstrate that adding Ti significantly enhances the passivation behavior of Ni-Nb metallic glasses and promotes the formation of stable oxide films with improved corrosion resistance in chloride-containing environments. Full article

Bilayer scattering films offer a practical route to independently controlling transmission and reflection in transparent optical systems, yet the separate roles of nanoparticle loading and stacking order remain underexplored. In this work, Al₂O₃/poly(methyl methacrylate) bilayer films with four concentration pairs (5/15, 15/5, 5/30, and 9/30 wt%) were fabricated by sequential spin-coating and characterized by wavelength-dependent transmittance, reflectance, integrating-sphere haze decomposition, and optical surface interferometry under both glass-side (G-incident) and scattering-layer-side (SL-incident) illumination. Two independent design parameters govern the optical response: (i) the maximum nanoparticle concentration sets the overall scattering regime, and (ii) the layer stacking order controls the partitioning between parallel transmittance (PT) and diffuse transmittance (DT). Bilayers with a maximum loading of 15 wt% maintained total transmittance (TT) ≈ 99% and moderate haze (25%–40%), while reciprocal 5/15 and 15/5 wt% pairs exhibited a ~15 percentage-point shift in PT despite identical total loading. Incorporation of a 30 wt% layer shifted films into a diffusion-dominant regime (DT > 68%, haze > 70%), and positioning this layer at the incident side under SL illumination suppressed visible reflectance below 1%. These results provide a practical composition–sequence design map for transparent optical coatings in display, privacy, and anti-glare applications. Full article

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article

The photocatalytic efficacy of metallic silver nanoparticle/zinc oxide (Ag-NPs/ZnO) composite thin films, COMP-Ag_x, with varying silver concentrations (0 mol% ≤ x ≤ 100 mol%), is investigated for the degradation of methyl orange (MO). The films were spin-coated on a silica glass surface at 600 °C utilizing the molecular precursor method (MPM). The XRD spectra of these composite thin films revealed three significant peaks corresponding to the diffraction planes of (0 0 2), (1 0 0), and (1 0 1), indicative of the formation of ZnO crystallites in diverse orientations, in conjunction with an additional signal for cubic Ag crystals. The magnitude of the ZnO peaks diminishes as the mol% of silver increases. The images from the SEM confirm the integration of Ag-NPs into the ZnO matrix. The UV/Vis absorption spectra exhibit a 410 nm surface plasmon resonance (SPR) peak for composite Ag-NP/ZnO thin films. The absorption spectra of ZnO and Ag-NP/ZnO composite thin films demonstrate the band gap of ZnO to be 3.4 eV, while the band gaps of the composite thin films nearly approximate that of ZnO. The decomposition rates of the MO solution indicate that composite thin films function effectively under visible irradiation compared to pure ZnO. The optical properties indicated that the SPR of Ag-NPs contributed to the visible responsiveness of the composite thin films. The SPR demonstrate significant visible light responsiveness and essential characteristics during photoexcited electron transfer from the Ag-NPs to the ZnO conduction band. Full article

This work investigates the use of two photoactive polymers, functionalized with quantum dots (QDs) (ZnS and CdTe/ZnS), to develop optical sensing hydrogel films through their interactions. It examines their responses to light stimulation for potential biological applications. The optical and morphological properties of the films were studied, revealing photoactive surfaces. The photoactive copolymers were synthesized based on poly(maleic anhydride-alt-2-methyl-2-butene), P(MAn-alt-2MB), and poly(maleic anhydride-alt-1-octadecene), P(MAn-alt-OD), by attaching the photochromic agent, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6-nitrobenzo pyran (SP). Subsequently, QD nanoparticles (ZnS or CdTe/ZnS NPs) were incorporated into the polymer solutions in the presence of a crosslinker agent, and were then spin-coated onto glass substrates under suitable conditions to produce porous-patterned films. These films were created using a one-step bio-inspired process called the breath figure (BF) method. SEM images of QD-containing samples show a photoactive porous surface resulting from a synergistic interaction between the components. The reversibility of these macroscopic properties results from photoinduced transformations at the molecular level. The light-emitting properties of the films were characterized by blue and violet fluorescence under UV light. Advances in film-forming techniques enable the creation of functional structures with important applications, such as microstructured hydrogel films for biological uses. Full article

Transparent conductive SnO₂ films, promising for application in electronic engineering, were obtained by sol–gel synthesis via mixing SnCl₂∙2H₂O and NH₄F solutions, followed by deposition onto glass substrates by centrifugation and heat treatment at 450 °C. The physicochemical processes of SnO₂ crystallization in water–alcohol solutions of SnCl₂ were analyzed depending on the concentration of the crystallization initiator NH₄F and the alcohols used. The sol–gel processing of the thin films was investigated using a Latin square approach. Three factors affecting the film formation conditions were varied at three levels to determine the best combination of film properties involving the maximum transparency and lowest specific electrical resistance. The effect of solvent type (ethanol, 1-butanol and isopropanol), the amount of introduced fluorine (5, 10, and 15 at. %) and the number of deposited layers (10, 15, and 20) on the composition, morphology, crystallization features, transparency and specific surface resistance of the synthesized thin films was studied. The obtained films of ~200–340 nm thickness exhibited ~78%–95% transparency in the visible spectrum range and specific surface resistance (ρ_s) from ~10⁹ to >10¹² Ω/sq. The optimal combination of thin (~250 μm) SnO₂<Sn> film target performances including transparency 84% and specific surface resistance ~10⁹ Ω/sq. was achieved in the case of their preparation in isopropanol with an average concentration of NH₄F (10 at. % F) and spin-on deposition of 20 layers. Full article

The present paper reports the preparation of a nanocomposite thin film consisting of calcium itaconate and graphene oxide (GO). The composite is a black powder consisting of individual shiny prismatic crystals at varying degrees of maturity. The crystal size distribution is quite narrow: from 3.6 to 6.2 μm in length and from 0.7 to 1.1 μm in width. Thin-film-based acetone sensor made of a nanocomposite was fabricated by spin coating of calcium itaconate–GO nanoparticles on glass plates. The thin-film acetone sensor was characterized using FTIR, XRD, SEM, TEM, and the low-temperature nitrogen sorption–desorption method. The sensor response time is 7.66 ± 0.07 s (s_r = 0.92%), and the relaxation time when blowing the surface with clean air or inert gas (nitrogen, argon) is 9.26 ± 0.12 s (s_r = 1.28%). The sensing mechanism of the sensor for detecting acetone at room temperature was also is proposed based on phenomenological understanding due to the absence of direct electronic/charge-transport evidence. Full article

Organic light-emitting diodes (OLEDs) have emerged as a leading high-resolution display and lighting technology, as well as for photo-therapeutic applications, due to their light weight, flexibility, and excellent color rendering. However, achieving long-term thermal stability and high energy efficiency remains a principal issue for their widespread adoption. Strong thermal robustness in OLED emitter materials is a critical parameter for achieving long device lifetimes, stable film morphology, reliable high-temperature processing, and sustained interface integrity in high-performance hosts. Bipolar emitters RB14 (N-(9-ethylcarbazole-3-yl)-4-(diphenylamino)phenyl-9H-carbazole-9-yl-1,8-naphthalimide), RB18 (N-phenyl-4-(diphenylamino)phenyl-9H-carbazole-9-yl-1,8-naphthalimide), and RB22 (N-phenyl-3-(2-methoxypyridin-3-yl)-9H-carbazole-9-yl-1,8-naphthalimide) were newly synthesized. RB18 is a yellow bipolar OLED emitter that has a glass transition temperature (T_g) of 162 °C and thermal durability (T_d) of 431 °C, which is the highest reported value for naphthalimide-based bipolar emitter derivatives for yellow OLEDs. Meanwhile, RB14 and RB22 are green OLED emitters that have glass transition temperatures (T_g) of 133 °C and 167 °C, and thermal durabilities (T_d) of 336 °C and 400 °C, respectively. We have fabricated OLED devices using these bipolar emitters dispersed in CBP host matrix, and we have found that the maximum EQEs (%) for RB14, RB18, and RB22 emitter-based devices are 7.93%, 3.40%, and 4.02%, respectively. For confirmation of thermal stability, we also used UV-visible spectroscopy measurements at variable temperatures on annealed spin-coated glass films of these emitter materials and found that RB22 is the most thermally stable emitter among these materials. Full article

NiO films were successfully deposited by sol–gel spin coating on Si, glass, and ITO-covered glass substrates. The impact of the film thickness (the different number of layers), annealing temperatures (from 300 to 500 °C), and the substrate type on the crystal structure, film morphology, optical, and vibrational properties was investigated. X-ray diffraction (XRD) revealed a polycrystalline structure and the appearance of the cubic NiO phase. Field Emission Scanning Electron Microscopy (FESEM) was applied to explore the surface morphology of NiO films, deposited on glass and ITO substrates. The oxidation states of Ni were determined by X-ray photoelectron spectroscopy (XPS). The presence of Ni²⁺ and Ni³⁺ states was supposed. UV–VIS–NIR spectroscopy revealed that NiO films possessed a high average transparency of up to 74.6% in the visible spectral range when they were deposited on glass substrates, and up to 76.9% for NiO films on ITO substrates. The thermal treatments and the film thickness slightly affected the film transparency in the spectral range of 450–700 nm. The work function (WF) of the samples was determined. This research showed that good properties of sol–gel NiO films can be compared to the properties of those films produced using complicated and expensive techniques. Full article

Bioactive coatings are of great interest for orthopedic applications, as they combine mechanical stability with biological functionality. In this study, stainless steel discs were coated with 45S5 bioactive glass doped with 1.0 wt% samarium by spin coating, followed by surface functionalization with benfotiamine through spraying. This strategy integrates three components: a metallic substrate as a stable and inexpensive support, a bioactive glass layer with well-known osteogenic potential, and a superficial organic layer of benfotiamine, a lipid-soluble analog of vitamin B1 with higher bioavailability. Samarium doping was selected based on previously reported antimicrobial potential against clinically relevant staphylococci, while the rationale for benfotiamine functionalization derives from literature describing vitamin B1 derivatives with anti-resorptive and osteogenic activity. The coatings were characterized by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) microscopy. Bioactivity was assessed by immersion in simulated body fluid (SBF), where phosphate bands indicated the formation of calcium phosphate phases (CaPs). Wettability tests showed a reduced contact angle after benfotiamine functionalization. Cytocompatibility was evaluated by LDH and MTT assays with MC3T3-E1 cells, suggesting overall biocompatibility and enhanced cell viability after 7 days for the benfotiamine-functionalized coatings. The present findings support a simple and cost-effective route to multifunctional coatings with potential relevance for future orthopedic applications. Full article

In this work, a sol–gel spin coating method was applied to obtain ZnO and ZnO:Ga thin films on a glass and ITO-coated glass substrate. Their structural, optical, and electrical properties were investigated with respect to their dependence on the different substrates, the number of layers (two and four), and the annealing temperature (300 and 400 °C). X-ray diffraction (XRD) patterns showed a hexagonal structure corresponding to the wurtzite phase for ZnO and ZnO:Ga films. ZnO films, deposited on a glass substrate, reveal greater crystallite sizes compared with ZnO films obtained from an ITO substrate. A Ga dopant worsened film crystallization. X-Ray photoelectron spectroscopy (XPS) proves the presence of Ga in a ZnO structure. ZnO films show lower transparency and haze values up to 44.12 (glass substrate) and 33.73 (ITO substrate) at a wavelength of 550 nm. The significant enhancement of ZnO film transparency is observed with Ga doping (with average transmittance in the visible spectral range above 85%, independent of the substrate used). Sheet resistance values are lower for ZnO:Ga films, and the figure of merit values are better compared with those of undoped ZnO films. Work function is studied for ZnO and ZnO:Ga films, deposited on Si, ITO, and glass substrates. Full article