Electrochromic Nickel Oxide Thin Films for Solar Light Modulation

Nickel oxide (NiO

Electrochromic Properties of Prussian Blue Thin Films Prepared by Chemical Deposition Method

The manifestation of electrochromic phenomena makes Prussian blue (PB) thin films very attractive, especially because they exhibit four-color polyelectrochromicity. In this work PB thin films were prepared by simple and low cost shemical deposition method. The films were deposited onto fluorine doped tin oxide (FTO) coated glass substrates. An electrochromic test device (ECTD) was constructed by using these films as working electrodes, and FTO coated glass as an opposite electrode in aqueous solution of 1 mol/dm3 KCl as supporting electrolyte. The electrochemical properties of the films were characterized by cyclic voltammetry. The obtained films exhibited electrochromism, changing color from deep blue in as deposited state into green, and back to blue and colorless. Visible transmittance spectra of PB films were studied in-situ in as deposited, colored and bleached states. From those spectra, contrast ratio (CR) and the optical band gaps Eg were evaluated. The dependence of the optical density (OD) on charge density was examined and the coloration efficiency (CE) was calculated to be 149.8 cm2C-1. The time response during the film switching between transparent and blue states was also examined

Electrochromism in tungsten oxide thin films prepared by chemical bath deposition

Tungsten oxide (WO3) thin films were prepared by a simple, economical, chemical bath deposition method onto fluorine doped tin oxide (FTO) coated glass substrates. The electrochemical properties of the films were characterized by cyclic voltammetry. The obtained films exhibited electrochromism, changing color from initially colorless to deep blue, and back to colorless. Visible transmittance spectra of (WO3) films were recorded in-situ in their both, bleached and colored states. From those spectra, absorption coefficient (a) and the optical energy gaps were evaluated. The dependence of the optical density on the charge density was examined and the coloration efficiency (h) was calculated to be 22.11 cm2 C-1. The response times of the coloring and bleaching to an abrupt potential change from -2.5 V to +2.5 V and reverse, were found to be 9.3 and 1.2 s respectively. The maximum light intensity modulation ability of the films, when the AM1.5 spectrum is taken as an input, was calculated to be about 50 %

Impedance and AC Conductivity of GdCr1−xCoxO3(x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Perovskite series GdCr 1 – x Co x (x = 0, 0.33, 0.5, 0.67 and 1) was obtained using a solution combustion method. The powder O 3 XRD was used for identification and structural characterization of the obtained perovskites. All compounds crystallize within the space group Pnma. The morphology of samples was studied using SEM. The impedance and AC conductivity of GdCr 1 – x Co x O were studied using impedance spectroscopy in a frequency range from 10 Hz to 10 MHz and in temperature interval 297–337 K. Changes in electric modulus and DC conductivity, with increasing of the value of x in the structures, were observed. The AC conductivity obeyed the universal power law, r(x)=r(0) + Ax 3 n and revealed semiconductor behavior. The calculated activation energies of existing processes varied with the cobalt content and applied frequency. The impedance spectra showed non-Debye behavior with a distribution of relaxation times for relaxation and conductive processes. The conduction mechanism for pure orthochromite and orthocobaltite was defined and two types of conduction were observed in the investigated temperature range for the complex perovskites. In order to explain the results, an equivalent circuit with fitted values of circuit components was proposed