Li-doped LiBO2 and LiNbO3 thin films have been studied and their optical and electrical properties determined. With doping the ionic conductivity of the films was found to increase substantially. The highest conductivity obtained with the doped films was about 4.5×10−6 S cm−1. All the films exhibited a high degree of transmission in the spectral region from 350 to 2500 nm. The remarkable increase in the ionic conductivity coupled to the preservation of a high optical transmission makes this doping technique highly attractive for devising ion conductors that can be used in transmissive solid-state electrochromic systems or the so-called ‘‘smart windows.’’

Optical and electrical properties of the LiBO,-LiF composite thin films prepared by thermal evaporation have been studied for their use as ion conductors in solid-state electrochrornic (EC) systems. All the LiBOz-LiF films exhibited a high degree of optical transmission (over 90%) and the best lithium ion conductivity attainable was about 8X 10e7 S cm-', a value considerably higher than that for the ionic conductivity of LiBOz. A typical activation energy of 0.545 eV was found for the composite film. The films obtained thus have a good potential for use as ion conductors in EC devices. 0 1995 American Institute of Physics.

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