Thermochromic Thin Films and Devices

This chapter is devoted to the detailed discussion of transition metal oxide (TMO) thin film thermochromics. Vanadium dioxide (VO 2 ) being the most well-known and researched TMO showing highly efficient thermochromic switching in all aspects, most of the discussion here is focused on thin films of VO 2 . A wide range of topics, from the basics of the thermochromic mechanism to the historic development of VO 2 thermochromics to the characterization of the switching phenomenon (semiconductor-to-insulator transition, transition temperature, optical and electrical hysteresis, and switching), are covered in detail. The hysteresis exhibited by VO 2 thin films undergoing thermochromic switching is of utmost importance and is dealt with in detail along with the various parameters that affect the hysteresis. Some typical examples of the results for nanostructured and coarse grain VO 2 films are shown along with the effects of doping on the switching temperature. Among the wide-ranging possibilities that exist for these thin films, a few important applications are discussed.