Search results for "Dip-coating"
showing 10 items of 18 documents
Efficient blue emitting organic light emitting diodes based on fluorescent solution processable cyclic phosphazenes
2008
Solution processable blue fluorescent dendrimers based on cyclic phosphazene (CP) cores incorporating amino-pyrene moieties have been prepared and used as emissive layers in organic light emitting diodes (OLEDs). These dendrimers have high glass transition temperatures, are monodisperse, have high purity via common chromatographic techniques, and form defect-free amorphous films via spin/dip coating. The solution processable blue light emitting OLEDs reach current efficiencies of 3.9 cd/A at brightness levels near 1000 cd/m2. Depending on the molecular bridge used to attach the fluorescent dendron to the inorganic core, the emission wavelength changes from 470 to 545 nm, corresponding to bl…
3D Colloidal photonic crystal fabrication improved by AC fields for frequency conversion enhancement in photovoltaics
2011
We report on the fabrication of high-quality 3D colloidal photonic crystals, whose finality is to modify the emission properties of frequency converters for photovoltaic applications. The band structure of the photonic crystals can be used to enhance the emission of down- and up-converters materials embedded in the 3D structures. However, in order to achieve an efficient conversion the first step is to obtain highly ordered templates with appropriated dimensions. We analyze here the photonic crystals obtained by the dip-coating or vertical deposition method. Moreover, by using perpendicular AC fields during the assembly of the nanospheres, the quality of the packed structures has been impro…
Synthesis, characterization, and hierarchical organization of tungsten oxide nanorods: spreading driven by Marangoni flow.
2009
Tungsten oxide nanorods were synthesized by a soft chemistry approach using tungsten alkoxide and trioctyl amine and oleic acid as the surfactants. The optical properties of the nanorods were studied. The nanorods were found to be soluble in a wide range of solvents like chloroform, cyclohexane, and so on. Upon solvent evaporation, the nanorods formed hierarchically organized solid state structures. Depending on the solvent used, the nanorods organized in different mesostructures. Moreover, the organization of the nanorods from mixtures of polar and nonpolar solvents was studied. Here, the Marangoni effect resulting from differences in the surface tensions of the two solvents was found to p…
Whispering gallery mode resonators coated with Au nanoparticles
2019
Whispering gallery mode resonators (WGMRs) are very interesting for sensing because a resonance shift could be caused by any perturbation of the surrounding environment. Additionally such a resonator is coated with nanomaterials to tailor and enhance the sensitivity for a specific purpose. WGMR were fabricated using standard telecommunication fiber and a hydrogen flame, characterized using the scan method to obtain the quality factors and then coated with gold nanoparticles (Au NPs) using dip coating method and characterized again for comparison. Au NPs were chosen because their positive impact on microresonator sensitivity has been mentioned before and the surface can later be functionaliz…
Investigations of TiO2 films deposited by different techniques
1991
High refractive TiO2 films deposited by reactive electron beam evaporation, reactive ion plating and dip coating have been characterized by optical spectroscopy, electron spectroscopy for chemical analysis, Rutherford backscattering spectroscopy, nuclear reaction analysis and Raman spectroscopy. The spectral refractive index n exhibits a strong dependence on the deposition conditions. These findings will be connected to variations in density, stoichiometry, hydrogen content (H2O) and binding structure of the layers. A strong correlation is found between optical quantities and microscopic properties of TiO2 films.
Optical planar Bragg grating sensor for real-time detection of benzene, toluene and xylene in solvent vapour
2012
Abstract We report on an optical planar Bragg grating sensor functionalized by a comparatively simple method to detect substances such as benzene, toluene and xylene (BTX). The functionalization is performed by allyl substituted γ -cyclodextrin derivatives which are immobilized on the sensor surface by dip coating. Our results prove the capability of this functionalized sensor system to detect lowest concentrations of BTX in solvent vapour in real-time with a sensitivity of 3±0.4 pm/100 ppm for benzene, 8±1 pm/100 ppm for toluene and 32±1 pm/100 ppm for m-xylene. Taking into account the spectral resolution and repeatability of the interrogation system this corresponds to a minimum concentra…
PEMBUATAN SISTEM VAKUM OTOMATIS GAS H2S BERBAHAN TiO2-Ni/Al2O3 TERKONEKSI ARDUINO UNO PADA LABORATORIUM KIMIA
2021
Research has been carried out on the H2S gas sensor made of TiO2-Ni/Al2O3 which is connected to an automatic vacuum. The results showed that the optimum conditions for the variation of Ni doping metal levels were 20 mg / gram TiO2. The semiconductor material synthesis method used the sol gel method with TTiP precursor which was made at pH 7. Coating of the sol gel solution on the Al2O3 substrate used a dip coater with a decrease speed of 1 cm / minute and was carried out 7 times of immersion. The characterization of synthetic results used UVVis, XRD, FTIR and SEM-EDX. The band gap value resulting from Ni doping is 2.75 eV from 3.2 eV, XRD identification shows that TiO2 is anataseic and dete…
Direct Writing on Copper Ion Doped Silica Films by Electrogeneration of Metallic Microstructures
2017
International audience; A facile and rapid localized electrochemical reduction of colloid copper particles is proposed using the scanning electrochemical,microscope (SECM), technique. In this purpose, thin films of composite silica :glass containing copper salts were prepared by the sol-gel method via the dip coating technique. Acid-catalyzed tetraethylorthosilane (TEOS) solutions charged with copper nitrate were used as precursors. This one-pot experiment can be performed in mild conditions. The localized generation of copper metallic nanostructures on silica film has been performed by electroreduction of methyl viologen on an ultramicroelectrode (UME). The UME generates reducing species, …
Preparation of Photocatalytic Nanostructured TiO<sub>2</sub> Thin Films
2008
Photoactive films consisting of pure anatase, brookite or rutile were deposited on glass slides by a dip coating process from water dispersions or solutions obtained by using TiCl4 as the precursor. The films were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The photocatalytic activity of the various samples was evaluated by using the photooxidation of 2-propanol in gas solid regime as probe reaction. Brookite and anatase films showed a good photoactivity degrading the substrate and the propanone produced during the reaction.
Photocatalytic thin films of TiO2 formed by a sol-gel process using titanium tetraisopropoxide as the precursor
2008
Abstract Thin TiO 2 films were prepared with the dip-coating technique by using sols deriving from titanium tetraisopropoxide. TiO 2 films were formed on glass substrates previously covered by a SiO 2 layer obtained from a tetraethylortosilicate sol. The films, after a thermal treatment at 673 K, mainly consisted of TiO 2 anatase. The samples were characterised by X-ray diffraction, UV–Vis spectroscopy, scanning electron microscopy and atomic force microscopy. The photoactivity of the various films was tested by using as probe reaction the photo-oxidation of 2-propanol in gas-solid regime. The photoreactivity results indicated that the TiO 2 films were efficient for degrading 2-propanol und…