Electrochromics for energy efficient buildings: Towards long-term durability and materials rejuvenation

•The importance of “smart windows” for energy efficient windows is summarized.•The structure of electrochromic device is introduced.•The role of Ti in WO3 thin films is discussed.•Electrochromic performance can be re-gained by galvanostatic de-trapping.

Electrochromic devices such as “smart windows” for energy efficient windows must be durable enough for many years of practical use. Typical devices employ films based on W oxide and Ni oxide, and this paper surveys recent progress on durability-related issues for these materials. In the case of W oxide, we discuss the beneficial effects of Ti addition, and we describe recent and unexpected progress concerning galvanostatic rejuvenation of aged W oxide films. For Ni oxide, we report how charge exchange declination during extended voltammetric cycling can be modeled in terms of a power law.