Optical and chemical properties of electrochromic oxide films for smart windows

摘要

The band structures of cubic WO_3 and LiWO_3 and the vibronic properties of W_xO_y clusters(x=1-12,y=2-52) were calculated.The band gaps of WO_3 and LiWO_3 are indirect and the incorporation of lithium ions results in te widening of the band gaps.Vibronic studies on clusters revealed that cewrtain molecules give optical transitions from oxygen orbitals to tungsten orbitals,similar to the results of band calculations.However,accumulation of (WO_60~(6-) up to 12 octahedra does not yield optical transition from O to W:but between oxygen atoms at different positions.An attempt to make a link between molecular and bulk characteristics of WO_3 is made to intewrpret its optical and chemical properties.