Long-life Inorganic Electrochromic Device Based on WO₃ and PB Films with Fast Switching Respond

Abstract

Complementary electrochromic devices were fabricated by using tungsten trioxide (WO3) film as working electrode, Prussian blue (PB) film as counter electrode and 0.1 M lithium perchlorate in propylene carbonate as electrolyte. The XRD result presents that WO3 and PB films are amorphous, which is favourable for a fast ion intercalation-deintercalation process. The device was tested under potentiostatic control using ±1.3 V steps, and changed its color between blue and colorless. It has a fast-switching respond (about 1.5 s for colouring and 2 s for bleaching) and could withstand 100,000 cycles with little change in its optical contrast.

Capturing ion trapping and detrapping dynamics in electrochromic thin films

“…We start from the most used potential window for WO 3 , i.e., 2.0–4.0 V vs Li 25 – 27 . Figure 1a shows cyclic voltammetry (CV) curves of WO 3 , indicating a typical amorphous structure.…”

“…Despite the fact that the phenomenon of electrochromism has been discovered for over 50 years 22 – 24 , and associated research as well as commercialization also keep growing with enhanced durability of WO 3 25 – 27 , performance degradation upon cycling is inevitable and its origin is still far from clear 24 , 28 – 32 , which largely limits the development of superior devices. The ion trapping/detrapping phenomenon reported a few years ago provides a new vista to reframe the electrochromism field and also pave the way to extend the lifetime of WO 3 thin films 28 , 33 – 35 .…”