CdS modified TiO2 films showing multicolor switching and enhanced optical contrast

Abstract

In this work, we first studied the effects of CdS quantum dot modification on the electrochromic properties of TiO₂ films in a Li ion containing organic electrolyte. Driven by an external potential, the CdS modified TiO₂ (TiO₂/CdS) film achieves reversible coloration and discoloration. In particular, the TiO₂/CdS film exhibits multistage color switching from yellow (original state), to green (−1.5 V), to black (−2 V) in the coloration process, then to brown (−0.6 V) in the discoloration process. Besides, an improved optical contrast window of about 79.7% at 624 nm, an enhanced coloration efficiency of 70.8% and a half shortened coloration time of 12.7 s are achieved for the TiO₂/CdS film, when compared with those of a pure TiO₂ film. This work not only presents a novel electrochromic material with enhanced electrochromic properties, but also brings us a new insight into exploring the electrochromic functions of metal-chalcogenides.