A self-powered electrochromic device driven by a nanogenerator

Electrochromic (EC) devices are capable of reversibly changing optical properties upon charge injection and extraction driven by an externally applied voltage. A nanogenerator (NG) is a device that converts mechanical energy into electricity. This paper demonstrates a self-powered EC device driven by an NG. An average visible optical modulation (Delta T-vis) as large as 15.3% was obtained, with electrochromic response time (ERT) and coloration efficiency (CE) of 10 seconds and 58.7 cm(2) C-1, respectively. Such a performance is comparable to an EC when powered by a hardwired DC power. This study indicates that the self-powered electrochromic system can be a candidate for monochrome displays or electronic billboards.