IN-SITU SPECTROSCOPIC INVESTIGATIONS OF ELECTROCHROMISM AND ION-TRANSPORT IN A POLY(3,4-ETHYLENEDIOXYTHIOPHENE) ELECTRODE IN A SOLID-STATE ELECTROCHEMICAL-CELL

Results of optical absorption spectroscopy during doping/undoping of p oly(3,4-ethylene-dioxythiophene (PEDOT) acting as an electrode in a so lid state electrochromic cell are presented. We found that PEDOT is we ll suited for applications in electrochromic displays. The change in o ptical absorption in the visible region is appropriate for a smart win dow and the required applied voltage is small (+/- 1.5 V). The switchi ng time at room temperature, from fully coloured to fully bleached is about 4 s and the stability upon repeated switching is very good. We a ttempted to use in situ Raman spectroscopy for identification of the i ons moving into and out of a PEDOT polymer electrode during electroche mical cycling. Unfortunately, the Raman signal from the conjugated mat erial is strong enough to dominate the cell spectra, preventing the id entification of the moving ions. But this also means that the solid st ate electrochemical cell can be used for in situ Raman studies on conj ugated polymers during electrochemical doping.