Electrochromic properties of lithium doped WO3 films prepared by the sol-gel process

The electrochemical responses of amorphous thin films of lithium doped tung sten trioxide (LixWO3) prepared by the sol-gel method were studied. The ele ctrode mass change in the oxide films during cyclic voltammetry and chronoa mperometry measurements was evaluated with electrochemical quartz crystal m icrobalance (EQCM). The electrode mass change and electrochemical performan ces depend on the lithium doping level. Higher lithium doping levels lead t o better electrochemical performances and to higher electrode mass changes in the insertion- deinsertion process. The electrochromic properties of the films investigated in situ using a spectroelectrochemical method are in ag reement with EQCM measurements. The bleaching process in the lithium doped film was complete whereas in pure WO3 films a residual coloration was obser ved. (C) 2001 Elsevier Science Ltd. All rights reserved.