Electrochromic Properties of NiO Thin Coatings

In this work, we report the role of structure on electrochromic behavior of nickel oxide thin coatings deposited via chemical vapor deposition on ITO-coated glass in (EtCp)2Ni–O2–Ar and (EtCp)2Ni–O3–O2–Ar reaction systems. The structure and chemical composition were analyzed and then correlated with electrochemical response and transmittance modulation when immersed in 1 M KOH electrolyte. The NiO exhibits an anodic coloration, reaching an optical density modulation of 0.66 between colored and bleached state at 550 nm, with a color efficiency of 30.7 cm2C-1. Very fast switching between states was obtained, the coloration and bleaching time did not exceed 0.05 sec.

A Photobleaching/Photoblinking analytical model for LSFCM imaging

Laser scanning fluorescence confocal microscope (LSFCM) imaging is an extensively used modality in biological research. However, these images present low signal to noise ratio and a time intensity decay effect due to the so called photoblinking/photobleaching (PBPB) phenomenon that corresponds to an intensity fading of a fluorescent probe along the time, as shown in Figure 1. This effect is caused by quantum phenomena associated with the electronic excitation and photochemical reactions among the fluorescent and the surrounding molecules induced by the incident radiation that temporarily or irreversibly destroy their ability to fluoresce. Since illumination is needed to excite and observe the tagging fluorescent proteins in the specimen and all the fluorophores will eventually photobleach upon extended excitation, the acquisition of this type of images becomes a hard task for long exposures.There are in the literature several proposals to model this fading effects and among them the single and double exponential are the most used. However, simple and tractable theoretical models based on the physics of the observation process to support these empirical laws are not available. In this work, that theoretical model, supported on the underlying physics of the process, is derived to describe the PBPB effect (see Figure 2).From a fluorescence point of view, tagging molecules can be in three main states (see Figure 3), i) ON-state, where they are able to fluoresce and be observed, ii) OFF-state, where they are temporarily not able to fluoresce and therefore are not visible and finally at the iii) BLEACHED-state where they become permanently OFF. Here, a continuous time differential equation dynamic model is proposed to describe the number of molecules at the ON-state, nON, along the time. The model is based on the underlying quantum mechanic physics theory of the observation process associated with this type of images and the common empirical weighted sum of two decaying exponentials (DExp), usually used in the literature, is derived from the model. The parameters βON and βOff are the transitions rate from and to the ON-state respectively and ξis the decay rate associated with the transitions for the permanent BLEACHED state.Experiments with synthetic and real data are presented to validate the PBPB model and estimate the physical variables associated with the process. Intensity decay from real data and the corresponding theoretical curve are compared and displayed in Figure 4.This work was supported by the FCT project [PEst-OE/EEI/LA0009/2011]. The authors thank Dr. José Rino and Profa Carmo Fonseca, from the Molecular Medicine Institute (IMM) of Lisbon, for providing biological technical support and the real data used in this paper.

Smart Windows with Different Thicknesses of V2O5 as Ion Storage Layers

Smart windows were fabricated with different thicknesses of amorphous V2O5, which acts as an ion storage layer. In these devices, V2O5 was deposited by thermal evaporation at a substrate temperature of 200 oC, and an electrochromic layer (WO3) was deposited by electron beam evaporation at a substrate temperature of 250 oC. Both layers were amorphous. V2O5 was found to exhibit direct-forbidden electron transitions, whereas the WO3 layer exhibited indirect-allowed electron transitions. An increase in the thickness of V2O5 from 78 nm to 313 nm reduced the colouration efficiency from 64 to 48 cm2/C, and the time of the transmission variation curve from the coloured state to the bleached state was increased from 82.41 s to 558 s.

NANOPOROUS NiO BASED ELECTROCHROMIC WINDOW

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.

High Reflectivity Modulation Electrochromic Windows

ABSTRACTIn this paper we report the fabrication of high reflectivity modulation electrochromic Windows (ECW's) which have exhibited a colored state reflectivity of more than 50% for the wavelength range of 1 to 2.5 µm with an average bleached state reflectivity of 20%. The transmissivity of these ECW's in the colored state was less than 5% and in the bleached state it averaged 60%. The materials employed were tungsten oxide (nominally WO3) for the first electrochromic electrode, lithium cobalt oxide (nominally LiCoO2) for the second, complementary, electrochromic electrode, lithium phosphorus oxynitride (Lipon) for the ionic conductor (electrolyte), and indium tin oxide (ITO) and indium oxide (In2O3) for the two transparent electronic conductors. The predicted and measured reflectivity of the ECW's were influenced by the first transparent conductor (TM) in relation to its thickness and optical properties. Devices without a TC1 exhibited the highest reflectivity modulation, It was also concluded that two of the main limitations to the degree of reflectivity modulation attainable with the ECW's were lithium insertion into TC1 and electronic transport through the electrolyte.