Search results for " ELECTROCHEMICAL"
showing 10 items of 141 documents
Efficient light-emitting electrochemical cells using small molecular weight, ionic, host-guest systems
2015
This work has been supported by the Spanish Ministry of Economy and Competitiveness (MAT2014-55200). Light-emitting electrochemical cells (LECs) based on fluorescent host-guest small molecules system are reported. The LECs show electroluminescence coming solely from the guest, with an external quantum efficiency (EQE) of 2.0%, which is very close to the theoretical maximum EQE (2.2%) for this particular system. This work demonstrates the possibility to obtain high efficiency devices employing low-cost materials, making host-guest systems a real alternative to more traditional semiconducting polymer or transition metal compounds. Postprint Peer reviewed
Flexible light-emitting electrochemical cells with single-walled carbon nanotube anodes
2016
Abstract In this work, we demonstrate flexible solution processed light emitting electrochemical cells (LECs) which use single-walled carbon nanotubes (SWCNTs) films as the substrate. The SWCNTs were synthesized by an integrated aerosol method and dry-transferred on the plastic substrates at room temperature. The addition of a screen printed poly (3,4-ethylene dioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS) film onto the nanostructured electrode further homogenizes the surface and enlarges the work function, enhancing the hole injection into the active layer. By using an efficient phosphorescent ionic transition metal complex (iTMC) as the active material, efficacies up to 9…
Electrochemical discrimination of manufacturing types of pottery from Magna Mater Temple and Fora of Nerva and Caesar (Rome, Italy)
2018
Abstract The voltammetry of immobilized microparticles (VIMP) methodology is applied to a series of pottery samples from the Roman sites of Nerva's Forum (second half of 9th-early 11th A.D), Caesar's Forum (second half of 9th-early 11th A.D) and Magna Mater Temple (III century). The VIMP sampling applied to voltammetric and electrochemical impedance spectroscopy (EIS) measurements was applied by the first time to acquire archaeometric information on archaeological pottery. VIMP measurements using pressed sample pellets on gold electrodes in contact with air-saturated 0.10 M H2SO4 have permitted to detect voltammetric signals for the reduction/oxidation of Fe and Mn minerals as well as catal…
Nanostructured anode material for Li-ion batteries
2010
The present paper focuses on a nanostructured SnCo alloy electrochemically prepared by template method in view of its use as anode material alternative to graphite in lithium-ion batteries. The fabrication of SnCo nanowire arrays was carried out by potentiostatic co-deposition of the two metals by using nanostructured anodic alumina membranes as template. Electrochemical tests on lithiation-delithiation of these SnCo electrodes in conventional organic electrolyte (EC:DMC LiPF6) at 30°C showed that their specific capacity was stable for about the first 12 cycles at a value near to the theoretical one for Li22Sn5 and, hence, progressively decayed.
Electrogeneration of Diiodoaurate in Dimethylsulfoxide on Gold Substrate and Localized Patterning
2016
International audience; A localized etching of gold surface by scanning electrochemical microscope technique is presented where a dimethylsulfoxide-based electrolyte charged with iodine is used. The electrogenerated triiodide ion at the platinum ultramicroelectrode tip (feedback mode) acts as an oxidant for gold surface. The effects of electrode diameter and the bias time have been investigated. The approach curve method was used to hold the electrode tip close to the gold surface. A scanning electron microscope is used to observe the etched gold surfaces where disk-shaped dots are generated. The diameter of these holes depends directly on the Pt electrode diameter and the bias time.
Template Electrochemical Growth and Properties of Mo Oxide Nanostructures
2014
This work is aimed at studying the growing process of nanostructures electrodeposited from molybdate aqueous solutions at different pH values into pores of polycarbonate membrane templates. The challenging issue was the opportunity to investigate a rather complex deposition process in a confined ambient, where electrochemical conditions are quite different from those usually established for deposition on a flat substrate. Nanostructures were grown from a bath containing Mo7O246– (NH4)6Mo7O24·4H2O) at different concentrations (50–100 g/L), at a constant cathodic current density of 2 mA/cm2 (electrodeposition area ∼8 cm2). Nanostructured deposit was characterized by XRD, EDS, Raman, XPS, and …
Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers
2015
Abstract Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb 2 O 5 ) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal…
Passive Behavior and Passivity Breakdown of AISI 304 in LiBr Solutions through Scanning Electrochemical Microscopy
2014
The passive behavior and passivity breakdown of AISI 304 stainless steel in LiBr solutions has been investigated by means of scanning electrochemical microscopy (SECM). The sample generation - tip collection (SG-TC) mode was used to operate the SECM and the tip potential was biased to detect the electroactive species. The evolution of the current at the ultramicroelectrode tip with the applied potential within the passive range was followed at different LiBr concentrations. Results show that the absolute value of the current at the tip increases with the applied potential. Additionally, SECM was also used to detect stable pits formed on the stainless steel surface in a 0.2 M LiBr solution. …
Highly phosphorescent perfect green emitting iridium(iii) complex for application in OLEDs.
2007
A novel iridium complex, [bis-(2-phenylpyridine)(2-carboxy-4-dimethylaminopyridine)iridium(III)] (N984), was synthesized and characterized using spectroscopic and electrochemical methods; a solution processable OLED device incorporating the N984 complex displays electroluminescence spectra with a narrow bandwidth of 70 nm at half of its intensity, with colour coordinates of x = 0.322; y = 0.529 that are very close to those suggested by the PAL standard for a green emitter. Bolink, Henk, Henk.Bolink@uv.es ; Coronado Miralles, Eugenio, Eugenio.Coronado@uv.es ; Garcia Santamaria, Sonsoles Amor, Sonsoles.Garcia@uv.es
CF3 Substitution of [Cu(P^P)(bpy)][PF6 ] Complexes: Effects on Photophysical Properties and Light-Emitting Electrochemical Cell Performance
2018
Herein, [Cu(P^P)(N^N)][PF6 ] complexes (P^P=bis[2-(diphenylphosphino)phenyl]ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos); N^N=CF3 -substituted 2,2'-bipyridines (6,6'-(CF3 )2 bpy, 6-CF3 bpy, 5,5'-(CF3 )2 bpy, 4,4'-(CF3 )2 bpy, 6,6'-Me2 -4,4'-(CF3 )2 bpy)) are reported. The effects of CF3 substitution on their structure as well as their electrochemical and photophysical properties are also presented. The HOMO-LUMO gap was tuned by the N^N ligand; the largest redshift in the metal-to-ligand charge transfer (MLCT) band was for [Cu(P^P){5,5'-(CF3 )2 bpy}][PF6 ]. In solution, the compounds are weak yellow to red emitters. The emission properties depend on the substitu…