Accelerated Life Test of Electrochromic Devices Using Charge Balance Control

Abstract

We fabricated 10mm x 10 mm WO3 electrochromic devices (ECDs) using nanoparticle deposition system (NPDS), a type of coating method using kinetic spray. NPDS has the advantage of mass production due to relatively its low pressure and low temperature, while it forms porous surface having bad effect on the durability. In order to verify durability of ECDs, we developed an optical transmittance measurement and voltage control system that enables dynamic control. We then characterized WO3 ECDs focusing on the relationship between transmittance and current under well-known static operating conditions. On the basis of above result, a new algorithm for accelerated life test was proposed considering charge balance and then we conducted the accelerated life test during 1,000,000 cycles. The result showed that optical performance maintained until the test ends. After the accelerated life test, the sample persevered its transmittance performance as 45.4% transmittance difference even after the sample underwent long time operation. It was verified that the durability of ECDs could be enhanced by adopting dynamic control, not using expensive fabricating method.