A review of the growth of V2O5 films from 1885 to 2010

This year is the 125th anniversary of the first synthesis of V2O5 gels. The fascinating properties and wide application range of V2O5 thin films have attracted significant attention over the past decades. Its wide optical band gap, layered structure, good chemical and thermal stability and excellent thermoelectric and electrochromic properties have made V2O5 a promising material for industrial applications such as gas sensors, electrochromic devices, optical switching devices, and reversible cathode materials for Li batteries. Gels were the first form in which V2O5 was synthesized at the end of the 19th century. Interest started to grow in the 1980s due to the discovery of their semiconducting properties and their use in antistatic coatings in the photographic industry. The rapid development of the sol-gel process brought new interest in V2O5 gels. Following a short discussion of vanadium oxides and V2O5, I summarize all thin film preparation techniques known up to now and use reported optical band gaps to characterize different growth methods. An estimation of the Bohr radius for V2O5 is also presented. This article provides an up-to-date review of more than a century (1885-2010) of research on the growth of vanadium oxide thin films. Nonetheless, due to the huge number of publications in the field, only those are selected and described which, according to the author, contribute the most to the field's further development. (C) 2010 Elsevier B.V. All rights reserved.