Narrow Results

Nickel oxide films were coated onto FTO substrate at optimum conditions. The coated NiO films exhibited nanopore structure. The cyclic stability of the NiO films was studied using cyclic voltammetry. An electrochromic device has been built with the structure G/FTO/NiO/PMMA–PC–H⁺/WO₃/FTO/G. The device exhibits a change in optical transmission of 47.7% (colored 19.7% and bleached 67.4%) and optical density of 0.54 at 550 nm. The response time for coloration/bleaching of the device is 22.8 s/11.4 s. The device goes from transparent orange in the bleached state to gray color in the colored state.

Transparent and conducting aluminium doped ZnO (ZnO:Al) films having different Al:Zn ratio were deposited by simple sol–gel technique on glass substrates. The films were characterized by microstructural, optical and electrical studies. It was observed that the films were transparent but highly resistive. The films were annealed at 300°C in an (nitrogen (N₂) + hydrogen (H₂) - 95% + 5%) atmosphere to obtain low resistive films. While the films showed transparency of > 70% in the visible range, the resistivity of the films was of the order of 10^-3 Ω cm. The optical constants of the films were studied by a modified Kramers–Kronig model to study its variation with the change in aluminium (Al) concentration.

Pb(Zr_0.65Ti_0.35)O₃ (PZT) thin films were deposited on SrRuO₃ (SRO) buffer layer coated LaAlO₃ (LAO) substrates by RF sputtering method. X-ray diffraction analyses indicate that the PZT thin films show epitaxial orientation and the in-plane epitaxial relationship between film and substrate is deduced as (001)[010]_PZT‖(001)[010]_SRO‖(001)[010]_LAO. Despite the Zr-richcomposition, observations using transmission electron microscopy reveal that the PZT thin films exhibited tetragonal phase, which was due to the clamping effect of the substrates. The clamping effecton the electrical properties, especially on the dielectric properties, was evaluated. Ferroelectric measurements show that PZT films with LAO/SRO substrates were fatigue-free. However, the test of dielectric property dependences on temperature manifests a relatively low Curie temperature of the PZT films. The loss tangent decreasedwith increase intemperature. Owing to the release of clamping stress, the loss tangent decreased dramatically while the temperature was approaching the phase transition temperature of PZT thin films.

Titanium thin films were deposited by DC magnetron sputtering. The glancing angle deposition (GLAD) method was implemented to prepare two series of titanium films: perpendicular and oriented columnar structures. The first series was obtained with a conventional incident angle α of the sputtered particles (α = 0°), whereas the second one used a grazing incident angle α = 85°. Afterwards, the films were annealed in air using six cycles of temperature ranging from 293 K to 773 K. DC electrical conductivity was measured during the annealing treatment. Films deposited by conventional sputtering (α = 0°) kept a typical metallic-like behavior versus temperature (σ_{300 K} = 2.0 × 10⁶ S m^-1 and TCR_{293 K} = 1.52 × 10^-3 K^-1), whereas those sputtered with α = 85° showed a gradual transition from metal to dielectric. Such a transition was mainly attributed to the high porous structure, which favors the oxidation of titanium films to tend to the TiO₂ compound.

Ba(Sn_0.02Ti_0.98)O₃ thin films (BTS) were prepared by sol–gel route and deposited by spin-coating on commercial Pt/Ti/SiO₂/Si substrates. By modifying the annealing conditions from 750°C at 1 h to 950°C at 15 min, the relative tunability n_r at 100°C in the paraelectric state increased from 45 to 70% while the DC dielectric permittivity ε′(0) increased as well. The evolutions of ε′(E) and n_r(E) are explained from Devonshire thermodynamic formalism. The very high value of tunability of 70% is explained by the grain size increase of our BTS thin films and the decrease of the dead layer effect when the annealing conditions are optimized.

Well crystallized TiO₂ nanoparticles were prepared by hydrothermal and sol–gel routes, respectively. The morphologies, structures, crystallinity and optical properties of resulted TiO₂ nanoparticles-based thin films via the two methods were examined by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and reflectance spectra. In addition, comparison of photovoltaic performance of TiO₂ nanoparticles-based thin films by the two methods was performed. It is found that the maximum energy conversion efficiency of 4.06% was achieved based on the obtained electrode via hydrothermal, which is much better than that of the sol–gels route. The uniform film structure with improved dye absorption capability, increased diffused reflectance property and relatively low charge recombination rates for injected electrons are believed to be responsible to the superior photoelectrochemical properties of dye-sensitized solar cells (DSSC) via hydrothermal route.

This paper reports on the fabrication of CuO_x films to be used as hole transporting layer (HTL) in CH₃NH₃PbI₃ perovskite solar cells (PSCs). Ultra-thin CuO_x coatings were grown onto FTO substrates for the first time via aerosol-assisted chemical vapor deposition (AACVD) of copper acetylacetonate in methanol. After incorporating into the PSCs prepared at ambient air, a highest power conversion efficiency (PCE) of 8.26% with HTL and of 3.34% without HTL were achieved. Our work represents an important step in the development of low-cost CVD technique for fabricating ultra-thin metal oxide functional layers in thin film photovoltaics.

An obvious unipolar resistance switching is observed in BaTiO₃/ZnO/BaTiO₃/Carbon films. The resistance switching effect and the set voltage can be modulated by light irradiation. The RS ratio increases with light intensity. These phenomena are explained using trap/detrap mechanism.

In this paper, novel chestnut-like TiO₂ was successfully synthesized by the hydrothermal method. The presence of chestnut-like structure not only increased the density of active sites with a high accessibility, but also facilitated the diffusion of solvent and products. Then, the chestnut-like TiO₂ based thin films on FTO were successfully prepared by the doctor-blade method. Moreover, the thickness of thin films can be adjusted via different repeated times. After that, in order to further improve its photoelectric properties, the adoption of CdS sensitization with different time interval via chemical bath route was studied. Photoelectrochemical (PEC) measurements showed that CdS/TiO₂ photoelectrode under the optimal condition exhibited minimal resistance and the fastest charge transfer rate. The highest photocurrent density can reach 35.1$\mu$A$\cdot$cm${}^{-2}$, which is almost 5-fold than that of pure chestnut-like TiO₂ (7.6$\mu$A$\cdot$cm${}^{-2}$) based thin films. The enhanced PEC properties could be ascribed to the improvement of light harvesting and the formation of heterostructure to accelerate the separation of photo-generated electron-hole pairs.

AgBiS₂ films were prepared by direct current magnetron sputtering method by depositing atom ratio 1:1 of silver bismuth metal precursor on a common sodium-calcium glass substrate by rapid annealing under sulfur and nitrogen atmosphere. The annealing process was obtained by changing the annealing temperature and time. The films were characterized by XRD, UV-Vis, SEM, AFM, XPS. AgBiS₂ thin films were grown on the substrate through sulfide annealing. After annealing at 475${}^{\circ }$C for 30 min, the surface of the film is smooth and the roughness is the smallest. The average grain size grows to the maximum of 1.2 $\mu$m. The film has a strong absorption coefficient in the range of ultraviolet and visible light. The absorption limit is as high as 1400 nm, and the bandgap is 0.853 eV. Through the study of sputtered atomic layer deposition and sulfurized annealing, AgBiS₂ film was prepared on the substrate by magnetron sputtering for the first time. It provides a feasible method for the preparation of AgBiS₂ thin films. It has great potential in photovoltaic, photoelectric and other applications.

Thin TiO₂-films were synthesized for the first time by solid-phase low-temperature pyrolysis technique onto quartz glasses or silicon substrates. The obtained films are nanoscale; crystallize in a mixed anatase-rutile modification, which was confirmed by X-ray diffraction, scanning electron and atomic force microscopy (AFM) methods. The three-layer films’ thickness was 140 nm. The TiO₂-films consist of crystallites 12–27 nm, depending on the temperature treatment and phase composition. In addition, all of the obtained TiO₂-films are optically transparent regardless of synthesis conditions; the calculated band gap was 3.55 eV, which makes it possible to recommend TiO₂-films for use in optical filters and gas sensors.

Implementing bottom-up approaches to control the columnar architecture of thin films at the nanoscale is a powerful tool for developing surface properties. While inclined columns, zigzags or helices made of a single material are now commonly produced by oblique angle deposition processes, the creation of more complex and original structures associating at least two different materials still remains a challenging task, even more on silicon substrate. Herein, we show how to prepare tungsten/molybdenum columns exhibiting a checkerboard-like structure with motifs of a few tens of nanometers. Although understanding the growth phenomena becomes more problematic when two components are simultaneously provided during the film fabrication, this original combination of controlled mosaics in columnar thin films enables new opportunities to produce some unusual nanostructures for functional materials.

Rapid technological advancements in recent years have necessitated the creation of energy-related devices. Due to their unique properties, including an exceptional cycling life, safe operation, low processing cost, and a higher power density than batteries, supercapacitors (SCs) have been identified as one of the most promising candidates to meet the demands of human sustainability. To increase the energy density of SCs, several advanced electrode materials and cell designs have been researched during the past few years. Utilizing the Faradaic charge storage process of transition metal cations, transition metal compounds have recently received attention as prospective electrode materials for SCs with high energy densities. In this work, the structure, morphology and electrochemical properties of molybdenum oxide (MoO₃) films deposited via thermal evaporation technique and annealed at various temperatures were systematically investigated in order to examine the potential use of MoO₃ for supercapacitors. Electrochemical analysis confirmed the pseudocapacitance characteristics of the synthesized films. The annealing temperature affects the oxidation and reduction observed in the cyclic voltammetry (CV) plots. Areal capacitance of thin films annealed at 150°C was found to be maximum and this could be attributed to the formation of hollow tube-like nanostructures which provided more active sites, than films annealed at higher temperatures. This also influences the charge storage ability of the synthesized films. It would be logical to assume that additional research in this area will result in more interesting discoveries and, eventually, the vi-ability of those promising Mo-based compounds in high-tech energy storage systems.

Antimony Selenide (Sb₂Se₃) exhibits potential as a solar energy material owing to its optimal bandgap, lack of toxicity, and abundance of earth abundant elements. Currently, cadmium sulfide (CdS) serves as the predominant buffer layer for Sb₂Se₃ solar cells. However, the use of CdS hinders environmentally friendly advancement due to the toxic properties of the element cadmium. Hence, the quest for non-toxic buffer layers poses a significant challenge to the further advancement of Sb₂Se₃ solar cells. In prior research, tin oxide (SnO₂) has been explored as a buffer layer. Nonetheless, the efficiency of SnO₂/Sb₂Se₃ solar cells was hampered by the rough surface of SnO₂ films and the poor crystallinity of Sb₂Se₃ films. In this investigation, we enhanced device efficiency by improving the uniformity of the SnO₂ surface and enhancing the crystallinity of Sb₂Se₃ through spin-coating sulfur (S) onto the SnO₂ film. Detailed examinations were conducted on the structure, optical, and electrical properties of the respective SnO₂ and Sb₂Se₃ thin films. Ultimately, an efficiency of 3.38% was achieved using the spin-coated S:SnO₂ film, marking an 85% enhancement compared to the baseline device.