From irreversible transformation of VO2 to V2O5 electrochromic films

Issam Mjejri (1) , Mathieu Duttine (1) , Sonia Buffiere (1) , Christine Labrugère-Sarroste (2) , Aline Rougier (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 PLACAMAT - Plateforme Aquitaine de Caractérisation des Matériaux

Since its discovery, electrochromism, known as a modulation of the optical properties under an applied voltage, has attracted strong interest from the scientific community and has proved to be of significant utility in various applications. Although vanadium dioxide (VO2) has been a candidate of extensive research for its thermochromic properties, its intrinsic electrochromism has scarcely been reported so far. In this study, multi-electrochromism is described from VO2 thick films. Indeed, VO2 opaque film, doctor bladed from homemade monoclinic VO2 powder, shows a pronounced color modulation from orange to green and blue associated with an amorphization-recrystallization phenomenon upon cycling in lithium-based electrolyte. The strong memory effect allows to follow the coloration mechanism by combining various ex-situ and in-situ characterizations addressing both structural and electronic aspects. Upon cycling the multi-chromism of VO2 finds its origin in a transformation of VO2 into orange-V2O5 on oxidation while in reduction the blue color lithiated state illustrates a mixed vanadium oxidation state.

Mots clés: Electrochromism; VO2; memory effect; characterization

Domaines: Matériaux

Issam Mjejri, Mathieu Duttine, Sonia Buffiere, Christine Labrugère-Sarroste, Aline Rougier. From irreversible transformation of VO2 to V2O5 electrochromic films. Inorganic Chemistry, 2022, 61 (46), pp.18496-18503. ⟨10.1021/acs.inorgchem.2c02722⟩. ⟨hal-03862397⟩