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The two star-shaped viologens containing 1,3,5-substituted phenyl (1) and triphenylamine (2) central cores and n-hexyl chains were synthesized and characterized. Both compounds exhibited promising optoelectronic properties and underwent multiple oxidation/reduction processes resulting in various colors. Four possible redox states of tripyridium salt containing a phenyl or triphenylamine core can occur depending on the applied potentials. The wide color range, from colorless through blue, azure to green-gray, was observed during the electrochemical reduction of compound 1. In the case of compound 2, the color change observed during spectroelectrochemical measurements was from yellow to colorless during the cathodic process and from yellow to green during the anodic process. The observed color change for both viologens was reversible. The triphenylamine-cored viologen (2) also exhibited emission in visible range and solvatochromism. It also exhibited luminescence in the solid state when excited with a UV lamp. These studies provide insights into the design of advanced materials for applications in displays. [ABSTRACT FROM AUTHOR]

The two star-shaped viologens containing 1,3,5-substituted phenyl (1) and triphenylamine (2) central cores and n-hexyl chains were synthesized and characterized. Both compounds exhibited promising optoelectronic properties and underwent multiple oxidation/reduction processes resulting in various colors. Four possible redox states of tripyridium salt containing a phenyl or triphenylamine core can occur depending on the applied potentials. The wide color range, from colorless through blue, azure to green-gray, was observed during the electrochemical reduction of compound 1. In the case of compound 2, the color change observed during spectroelectrochemical measurements was from yellow to colorless during the cathodic process and from yellow to green during the anodic process. The observed color change for both viologens was reversible. The triphenylamine-cored viologen (2) also exhibited emission in visible range and solvatochromism. It also exhibited luminescence in the solid state when excited with a UV lamp. These studies provide insights into the design of advanced materials for applications in displays.

Polyaniline (PANI) is a commonly used electrochromic material due to its tunable optical properties under an applied potential. In order to fabricate large-area electrochromic devices, PANI has to be deposited uniformly in large scale. Unfortunately, the existing deposition techniques can hardly meet the requirement. In this work, sequential solution polymerization (SSP) technique is introduced for in-situ deposition of large-area PANI films. This process involves synthesis of hydrated vanadium pentoxide (HVO), formation of V2O5 precursor film and in-situ polymerization in an aniline monomer solution. PANI films with a size of 16 × 10 cm2 are realized using bar coating in ambient. This method is facile and efficient, compatible with roll-to-roll printing technology. Electrochromic devices based on SSP PANI films exhibit high optical contract in the vis-NIR region and good cyclability. This study demonstrates that SSP shows great potential in in-situ deposition of large-area PANI films for the development of optoelectronic modules.

Abstract: A new nanocomposite WO3 (NWO) film-based electrochromic layer was fabricated by a spray and electroplating technique in sequence. An indium–tin oxide (ITO) nanoparticle layer was employed as a permanent template to generate the particular nanostructure. The structure and morphology of the NWO film were characterized. The optical and electrochromic properties of the NWO films under lithium intercalation are described and compared to the regular WO3 film. The NWO films showed an improved cycling life and an improved contrast with compatible bleach-coloration transition time, owing to the larger reactive surface area. The nanocomposite WO3 film-based electrochromic device (NWO-ECD) was also successfully fabricated. Most importantly, the NWO film can be prepared on a large scale directly onto a transparent conductive substrate, which demonstrates its potential for many electrochromic applications, especially, smart windows, sunroof and displays. [Copyright &y& Elsevier]