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.