Photo-electrochemical synergistically induced ion detrapping for electrochromic device rejuvenation

Ion trapping in electrodes upon long-term cycling is found to be one of the main reasons for performance degradation in electrochromic devices. Galvanostatic and potentiostatic post-treatments can rejuvenate degraded electrochromic layers. However, these procedures require high oxidation potentials, which are neither safe for the electrode-electrolyte system nor compatible with the operation of a full device. In the present paper, we report that degraded electrochromic oxides can be rejuvenated by a photo-electrochemical synergistically induced ion detrapping procedure. The UV light-induced photocurrent assists ion detrapping and limits the applied potential to the safe range used for electrochromic switching. This approach has been demonstrated to be effective for several cathodic electrochromic oxides and can be directly implemented in a full device. Our findings provide new vistas for efforts to expand the lifespan of electrochromic devices and other ion intercalation-based devices.