Time filter

Source Type

Cartaxo, Portugal

New University of Lisbon and Ynvisible | Date: 2012-07-13

Tungsten trioxide (WO3) nanoparticles are synthesized via a sol-gel route using metallic tungsten as precursor and printed on a flexible electrode using inkjet printing in order to build solid-state electrochromic cells. A method for separate control of different spectral regions of the electrochromic device (near infrared and visible) is disclosed.

The composition and method for depositing and processing a solid transparent electrolyte polymerized by ultraviolet (UV) radiation are described. The electrolyte composition includes, at least, an ionic compound, a polymerizable material, a photoinitiator and a polar solvent. The electrolyte is deposited by printing techniques, such as inkjet printing.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: NMP.2012.1.4-2 | Award Amount: 4.59M | Year: 2012

Supramolecular chemistry studies chemistry beyond individual molecules, where molecules or macromolecules form larger entities by spontaneous self-assembly or by self-organisation. The resulting supramolecular architectures are held together by covalent bonds and a variety of non-covalent intermolecular interactions (hydrogen bonding, metal coordination, hydrophobic interactions etc). Spatially, the supramolecular systems can extend from a few nm to micron size or beyond, in 1, 2 or 3 dimensions, with hierarchical structures containing organisation at distinct characteristic length scales. Consequently, one can control and guide not only the chemical properties of supramolecular systems, such as adsorption affinity, reactivity or catalytic activity, but also the physical properties (mechanical, electrical, optical etc.) with spatial resolution, at different length scales and in different directions. Therefore, supramolecular systems have a potential functionality which tremendously surpasses the scope of classical molecular systems in the liquid state, or of classical porous solids. This potential functionality encompasses the type and number of functions which can simultaneously be fulfilled, as well as the range of viable operating conditions. While the variety of functions for supramolecular systems is only limited by the imagination of the supramolecular chemist, SACS focuses on the formation, via self assembly, of functional structures in restricted or controlled space to gain new properties resulting from the confinement and to enable the formation of assemblies with controlled geometries as well as size and shape and outstanding properties.

Jordao N.,New University of Lisbon | Cruz H.,New University of Lisbon | Branco A.,Ynvisible | Pinheiro C.,Ynvisible | And 2 more authors.
RSC Advances | Year: 2015

Gel switchable electrochromic devices based on disubstituted bipyridinium derivatives have been developed. The type of substituent from the 4,4′-bipyridinium cation and counter-ions can influence the reversibility and switching of colours of these electrochromic systems. Three switching colours (yellow, blue and red or violet) can be obtained for iodide salts due to dimer formation. In the case of bistrifluoromethanesulfonylimide [NTf2] salts only two reversible colour switches (transparent and blue) were observed. Complementary electrochromic performance including chromatic contrast (ΔT%); transition times between the bleached and coloured states; colouration efficiencies (CE), colour coordinates (CIE L∗a∗b∗) and preliminary cycling stability studies of the devices have been performed. The higher coloration efficiency is observed in the case of [(C10)2bpy][NTf2]2 (186.9 cm2 C-1), which is similar to other bipyridinium systems already reported in the literature. This journal is © The Royal Society of Chemistry 2015.

Costa C.,YDreams | Costa C.,New University of Lisbon | Pinheiro C.,Ynvisible | Henriques I.,Ynvisible | Laia C.A.T.,New University of Lisbon
ACS Applied Materials and Interfaces | Year: 2012

Tungsten oxide nanoparticles were synthesized via a sol-gel route using metallic tungsten as precursor, and were printed on a flexible electrode using inkjet printing in order to build solid-state electrochromic cells. Several spectroscopic techniques were used to characterize and compare tungsten oxide particles obtained from different origins. FTIR, Raman and X-ray diffraction spectroscopic measurements showed that the sol-gel synthesis described here produces nanoparticles mainly in an amorphous state with hexagonal crystalline domains and allowed the analysis of the hydration extent of those nanoparticles. The size was measured combining dynamic light scattering, sedimentation, and microscopic techniques (AFM), showing a consistent size of about 200 nm. The tungsten oxide nanoparticles were used to produce an ink formulation for application in inkjet printing. Solid-state electrochromic devices were assembled at room temperature, without sintering the tungsten oxide printed films, showing excellent contrast between on/off states. Electrochemical characterization of those films is described using cyclic voltammetry. The devices were then tested through spectroelectrochemistry by Visible/NIR absorption spectroscopy (400-2200 nm range), showing a dual spectroscopic response depending on the applied voltage. This phenomenon is attributed to the presence of two different crystalline states in accordance with results obtained from the spectroscopic characterization of the nanoparticles. The electrochromic cells had a good cycling stability showing high reversibility and a cyclability up to more than 50 000 cycles with a degradation of 25%. © 2012 American Chemical Society.

Discover hidden collaborations