Comparative studies of "all sol-gel" electrochromic devices with opticallypassive counter-electrode films, ormolyte Li+ ionconductor and WO3 or Nb2O5 electrochromic films

Laminated electrochromic (EC) devices are becoming increasingly important f or making "smart" windows and switchable displays. Mostly, polymeric Li+ io nic conductors in combination with vacuum deposited active electrochromic a nd counter-electrode films are used. In this paper we report on the develop ment of all sol-gel EC devices, that is, those where all three internal lay ers are prepared via the sol-gel route, including the ionically conductive inorganic-organic hybrid (ormolyte). The electrochemical and optical proper ties of EC devices are presented and the cycling stability and reversibilit y of their optical modulation assessed. The results show that WO3/ormolyte/ SnO2: Mo, WO3/ormolyte/SnO2: Sb, WO3/ormolyte/SnO2:Sb:Mo, Nb2O5/ormolyte/Sn O2 : Sb:Mo and WO3/ormolyte/LiCo-oxide exhibit a transmission modulation de pendent on the thickness of the active electrochromic and counter-electrode films and the thickness of the ormolyte layer. Electrochemical and optical properties of individual films are described and correlated with the stabi lity of the all sol-gel EC devices. (C) 1999 Elsevier Science B.V. All righ ts reserved.