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Structure and transport properties of titanium oxide (Ti2O, TiO1+, and Ti3O5) thin films
摘要： Titanium oxides have partially filled or empty d orbital and are stable at various oxidation states with different structures and unique properties. Here, three kinds of titanium oxide thin films of hexagonal Ti2O metal, cubic TiO1+d superconductor, and monoclinic g-Ti3O5 semiconductor, were successfully grown on a-Al2O3 substrates by a pulsed laser deposition technique, through ablating a pure titanium target under different oxygen pressures. The electrical resistivities of these films increase with increasing oxygen content. The metallic behaviors of Ti bulk and Ti2O film can be described by the Bloch-Grüneisen formula, and the semiconducting behaviors of TiO1+d films in normal state and g-Ti3O5 film obey the variable range hopping and the small polaron hopping conduction mechanisms, respectively. For titanium monoxide TiO1+d (1.05 ≤ 1+d ≤ 1.17) films, increasing oxygen content is accompanied by an increase of disorder, a decrease of electron density of states at the Fermi level, and an enhancement of carrier localization, leading to a suppression of superconductivity.
关键词： Electron energy-loss spectroscopy,Oxygen content,Superconductivity,Transport properties,Titanium oxide thin films,Pulsed laser deposition
更新于2025-09-19 17:15:36
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Synthesis and characterization of electro-spun TiO <sub/>2</sub> and TiO <sub/>2</sub> -SnO <sub/>2</sub> composite nano-fibers for application in advance generation solar cells
摘要： Due to rapid progressive research in the field of nano-technology, nanostructures are attaining tremendous deliberation. Precisely, among these, nano-fibers have accumulated unprecedented attention over the last few years owing to their superior properties such as large surface area to volume ratio. For advance generation solar cells, nano-fibers of metal oxides such as TiO2 have been widely employed as a working anode but due to the disadvantages of recombination of electrons, their coupling with other metal oxides is necessary to render them useful. This work reports the successful fabrication of TiO2, TiO2/SnO2 nano-fibers based film and study of the effect of polymer concentration upon it. The crystal structure of synthesized fibers was investigated using XRD, the morphology and chemical composition was analyzed using SEM and EDX, optical properties and chemical properties were studied using UV-VIS spectrophotometer and FT-IR while the electrical properties were studied using Hall Effect measurement system. It was revealed that the prepared TiO2-SnO2 nano-fibers exhibit enhanced conductivity, larger band-gap with enhanced photo voltaic properties than TiO2 nano-fibers. The prepared TiO2/SnO2 nano-fibers based solar cells provide an improved efficiency of 4.81% as compared to 1.8% efficiency of bare TiO2 nano-fibers.
关键词： nano-fibers,titanium oxide,tin oxide,solar cells,electro-spinning
更新于2025-09-16 10:30:52
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Nanoantenna Structure with Mid-Infrared Plasmonic Niobium-Doped Titanium Oxide
摘要： Among conductive oxide materials, niobium doped titanium dioxide has recently emerged as a stimulating and promising contestant for numerous applications. With carrier concentration tunability, high thermal stability, mechanical and environmental robustness, this is a material-of-choice for infrared plasmonics, which can substitute indium tin oxide (ITO). In this report, to illustrate great advantages of this material, we describe successful fabrication and characterization of niobium doped titanium oxide nanoantenna arrays aiming at surface-enhanced infrared absorption spectroscopy. The niobium doped titanium oxide film was deposited with co-sputtering method. Then the nanopatterned arrays were prepared by electron beam lithography combined with plasma etching and oxygen plasma ashing processes. The relative transmittance of the nanostrip and nanodisk antenna arrays was evaluated with Fourier transform infrared spectroscopy. Polarization dependence of surface plasmon resonances on incident light was examined confirming good agreements with calculations. Simulated spectra also present red-shift as length, width or diameter of the nanostructures increase, as predicted by classical antenna theory.
关键词： niobium-doped titanium oxide,mid-infrared plasmonics,nanoantenna
更新于2025-09-16 10:30:52
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Origin of the tunable carrier selectivity of atomic-layer-deposited TiOx nanolayers in crystalline silicon solar cells
摘要： Titanium oxide (TiOx) nanolayers grown by atomic layer deposition are investigated with respect to their application as carrier selective contacts for crystalline silicon (c-Si) solar cells. Although TiOx is known to act as an electron contact, in this work the selectivity of TiOx layers is found to be widely tunable from electron to hole selective depending on deposition conditions, post-deposition treatments, and work function of the metal electrode used. Using TiOx and an intrinsic hydrogenated amorphous silicon buffer layer, solar cell test structure exhibiting open-circuit voltages (Voc) as high as 720 and 650 mV are shown for electron and hole selective contacts, respectively. Surface photovoltage and capacitance-voltage measurements reveal that carrier selectivity is correlated with the amount of c-Si band bending induced by TiOx, which are governed not only by the effective work function difference at the Si/TiOx interface, but also by the negative fixed charge present in the TiOx layer. This new finding is in contrast to the previous model for carrier transport where selectivity is determined only by the asymmetric band offsets at the Si/contact interface. It highlights the influence of induced band bending to produce carrier depletion/inversion conditions, and the importance of its selectivity effect in a c-Si absorber.
关键词： Titanium oxide,Solar cells,Carrier selective contacts,Atomic layer deposition
更新于2025-09-16 10:30:52
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Titanium oxide hollow structure layer for dye sensitized solar cell by liquid phase deposition
摘要： In this study, polystyrene (PS) microspheres templates having different coating densities were prepared by drop casting PS microspheres with the diameter of 800 nm on indium tin oxide (ITO) glass substrate. TiO2 film was deposited on the PS microsphere template via liquid phase deposition (LPD) using a solution of ammonium hexafluoro-titanate [(NH4)2TiF6] and boric acid (H3BO3). A LPD-TiO2 hollow layer was prepared by removing PS microspheres via high-temperature sintering; this hollow layer acts as a barrier between the ITO and electrolyte interface in the working electrode structure of a dye-sensitized solar cell (DSSC). Because hollow layer has a large specific surface area, it increases dye adsorption and acts as a barrier layer to inhibit direct contact between ITO and electrolyte interface. Thus, the charge recombination rate between ITO and electrolyte interface is reduced and the electron transmission efficiency between the ITO and the working electrode is improved. Hollow layer (0.1 wt% PS, 50 nm) in the DSSC exhibited the optimum short-circuit current density (Jsc) of 12.75 mA/cm2, open-circuit voltage (Voc) of 0.71 V, fill factor of 62.19%, and photoelectric conversion efficiency (η) of 5.67%.
关键词： Hollow structure,Dye-sensitized solar cells,Titanium oxide,Barrier layer
更新于2025-09-16 10:30:52
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Sputter deposited titanium oxide layers as efficient electron selective contacts in organic photovoltaic devices
摘要： Organic photovoltaics (OPV) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPV typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO2) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO2 interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition method used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of around 100°C for the TiOx thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance, and the removal of any s-shape characteristics. Optical, structural, compositional and electronic energy-level characterizations of the TiOx layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape free PTB7:PC70BM devices are demonstrated for TiOx growth temperatures of 155°C.
关键词： Sputter Deposition,Metal Oxide Interlayers,S-Shape Free,Titanium Oxide,Organic photovoltaics
更新于2025-09-12 10:27:22
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High-performance and -stability graphene quantum dots-mixed conducting polymer/porous Si hybrid solar cells with titanium oxide passivation layer
摘要： Recently, conducting polymer/Si hybrid solar cells (HSCs) based on simple fabrication processes are highly attractive due to their low cost, but low conductivity of the polymer, high reflection index of Si, and large recombination loss on the Si back contact are major drawbacks that should be solved for the practical applications. Here, we first report HSCs composed of graphene quantum dots (GQDs)-mixed poly (3,4-ethylenedioxythiophene) (PEDOT:GQDs)/porous Si (PSi)/n-Si/titanium oxide (TiOx, back passivation layer). Maximum power conversion efficiency (PCE) of 10.49 % is obtained from the HSCs at an active area of 5 mm2, resulting from the enhanced conductivity of the PEDOT:GQDs, the reduced reflectivity of Si (the increased absorption) by the formation of PSi, and the prevented recombination loss at the Si backside due to the passivation. In addition, the HSCs of 16 mm2 active area maintain ~78 % (absolutely from 8.03 to 6.28 %) of the initial PCE even while kept under ambient conditions for 15 days.
关键词： conducting polymer,passivation,hybrid solar cell,titanium oxide,porous Si,reflectivity,graphene quantum dot
更新于2025-09-11 14:15:04
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Titanium-oxide based nanoscale and embeddable subzero temperature sensor using MIT deformation characteristics
摘要： In this research, we propose a nanoscale and embeddable subzero temperature sensor that is made with a temperature-dependent titanium-oxide based metal-insulator-transition (MIT) device. For a nanoscale two-terminal structured MIT device, the MIT device’s characteristics are noticeably changed from abrupt to gradual MIT under zero temperature, which is called MIT deformation. On the basis of the MIT deformation characteristics, subzero temperatures can be detected by reading current levels as temperature changes. Furthermore, this sensor has desirable sensing properties such as high-linearity and proper sensitivity. The obtained results strongly show that titanium-oxides with CMOS process compatibility, cost-effectiveness, nontoxicity, etc, can be applied at the nanoscale and embeddable on subzero temperature sensors on a chip.
关键词： nanoscale,embeddable,subzero,temperature sensor,titanium-oxide,differential temperature sensor
更新于2025-09-10 09:29:36
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Modification of kaolinite from Pará/Brazil region applied in the anionic dye photocatalytic discoloration
摘要： The incorporation of titanium oxide and other transition metals on the surface of different materials has been shown to be a promising strategy to improve the efficiency of photocatalytic processes aiming at the decontamination of aqueous systems caused by persistent organic contaminants such as dyes. The objective of this work was to evaluate the catalytic properties of nanocomposites based on the kaolinite (Kaol) with TiO2 incorporated, obtained from the sol-gel method, used in discoloration of the coomasie brilliant blue dye (CBB) in aqueous solution. The nanocomposites were prepared from the reaction of titanium tetraisopropoxide with purified natural kaolinite and calcined at different temperatures. The samples were characterized by the XRD, FTIR, SEM-XED, BET-BJH and diffuse reflectance spectroscopy techniques, which demonstrated the structure, crystalline pattern, as well as the incorporation of titanium in the clay structure, changes caused by modification in morphology, texture and energy gap. The photocatalytic tests were performed using 5 × 10?5 mol L?1, 1.0 and 1.5 g L?1 concentration, respectively, to the CBB dye solution and to the synthesized materials. Among the nanocomposites, the sample calcined at 300 °C, KaolBT-300, presented the best photocatalytic performance. The addition of the H2O2 oxidant to the solution containing KaolBT-300 at the concentration of 1.5 g L?1 increased the discoloration percentage to 97.31% of the CBB solution dye after 120 min of irradiation. The discoloration kinetics of the CBB dye obeys the pseudo-first-order velocity law. Finally, the reuse of the KaolBT-300 sample in three consecutive cycles of photocatalysis demonstrated a significant adhesion stability of the TiO2 particles on the clay surface, indicating that it can be used in advanced oxidative processes for the degradation of organic pollutants.
关键词： Natural clay,Sol-gel synthesis,Heterogeneous catalysis,Titanium oxide,Water treatment,Dye
更新于2025-09-10 09:29:36
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Effect of the preparation method and metal content on the synthesis of metal modified titanium oxide used for the removal of salicylic acid under UV light
摘要： Titanium dioxide modified with Ag and Fe was synthesized using two preparation methods, characterized and applied to the photocatalytic degradation of salicylic acid in aqueous solution. The modified TiO2 samples were prepared by the sol-gel and wet impregnation methods starting from titanium(IV) isopropoxide and using AgNO3 and Fe(NO3)3·9H2O as precursors of the modifiers, with their content varying between 0 and 5 wt.%. Catalysts characterization was based on powder X-ray diffraction (PXRD), nitrogen physisorption at 77 K, temperature programmed reduction (H2-TPR), chemisorption of NH3 at 343 K and X-ray photoelectron spectroscopy (XPS). The photocatalytic degradation of salicylic acid by modified TiO2 was investigated under ultraviolet irradiation at 298 K considering various concentrations of the catalyst, between 100 and 1000 mgcatalyst/dm3, and of the organic molecule, between 0 and 15 mg/dm3. The catalysts most active in the degradation of salicylic acid were those having the highest Fe content.
关键词： salicylic acid removal,photocatalysis,sol-gel method,Doped titanium oxide,wet impregnation method
更新于2025-09-09 09:28:46