Thickness-Dependent Coloration Properties of Glass-Substrate Viologen-Based Electrochromic Devices

Abstract

Blue viologen-based electrochromic devices on glass substrates were constructed with different internal active layer thickness by means of a thermoplastic spacer (DuPontTM surlyn1702). Optical measurements, chronoamperometry, and cyclic voltammetry (CV) were the techniques used for characterization. Coloration properties such as switching times for coloring and bleaching processes, coloration efficiency, and effective charge density, previously studied for a single device, are now obtained for several devices with different thicknesses. Dependence on thickness in the response times and in voltagedependent parameters of device equivalent electric circuit model was studied in previous works. In this paper, some of those parameters, such as Warburg diffusion, double-layer capacitance, and charge transfer resistance, obtained with electrochemical impedance spectroscopy, are related with the coloration properties and their dependence on the thickness obtained by the aforementioned chronoamperometric and CV characterization.

Efficient access to conjugated 4,4′-bipyridinium oligomers using the Zincke reaction: synthesis, spectroscopic and electrochemical properties

“…4,[17][18][19] The colour of cationic bipyridinium residues is highly dependent on the electronic ground state energy of the molecule, which can be finely tuned by varying the substituents. [20][21][22][23][24] There have been a number of studies concerning the synthesis of oligomers and polymeric materials containing 4,4′bipyridine units in the backbone. Typically, the electroactive 4,4′-bipyridinium groups are separated by at least one methylene residue.…”

Asymmetric molecular modification of viologens for highly stable electrochromic devices

“…The device colored at À1.2 V required a longer bleaching time due to the higher concentration of BHV + c, similar to the viologenbased Type I ECDs. 33,40,41 Coloration efficiency (h) values were compared at various voltages. The h is dened by h ¼ DOD/DQ ¼ log(T b /T c )/DQ, where DOD is the optical density contrast calculated by the logarithm of the transmittance ratio of bleached (T b ) and colored (T c ) states, and DQ is the amount of injected charge.…”

Inversión de los modelos de transferencia radiativa de dos flujos y de cuatro flujos para determinar los coeficientes de dispersión y de absorción para cristales líquidos dispersos en polímero

“…However, the three-extinction matching requirement is not observed when the sandwich structure of the characterized samples is approximated in a single layer method and a rule of three is applied to intrinsic and extrinsic coefficients [33,34,35]. Nevertheless, new optical constants of ITO thin film layer [36] recently obtained (that satisfied the threeextinction matching requirement) could be applied in previous works in multilayer method with the suspended particle device [39,40]. As future works, it would be of interest to apply this new procedure with polymer dispersed liquid crystals, with commercial [5] and with the eight samples characterized in the current work, in both single layer and multilayer methods.…”