Synergistic tungsten oxide/organic framework hybrid nanofibers for electrochromic device application.

Electrochromism is described as the reversible color change of a material between the redox states induced by application of an electrical potential. Electrochromic devices (ECDs) are able to control the throughput of visible light and solar radiation entering the buildings and provide energy efficiency by modulating optical transmittance. ECDs have many application areas such as smart windows of green buildings, full-angle information displays, controlled reflectance mirrors and thermal control of satellites. Various chemical compounds have been investigated and developed for the ECDs, such as inorganic complexes, organic molecules, metallo-supramolecules, electroactive polymers and metal oxides.

Hybrid films based on tungsten oxide and conducting polymers have gained considerable attention, since desirable electrochromic characteristics such as high optical modulation, rapid response time and excellent stability can be readily achieved. Nanostructured hybrid thin films of the system tungsten oxidepoly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (WO3- PEDOT:PSS) were synthesized by first forming a tungsten-oxide layer by surfactant-assisted electrochemical method, followed by deposition of a PEDOT:PSS layer.
In this contribution, we report on the synthesis of tungsten oxide/conducting polymer hybrids and characterization of electrochromic devices made with nanofibers of these structures. Our fabrication method involves chemical oxidative polymerization of EDOT(Pyrrole) with WO3 nanoparticles in different ionic liquids media for subsequent electrospinning of these hybrid materials. Moreover, our study goes one step beyond electrospinning as well, since nanofiber production from chemically synthesized tungsten oxide hybrids and their application in electrochromic devices have not been indicated heretofore to the best of our knowledge.