Investigation for a Highly Efficient Self-Powered Electrochromic Smart Window for Fast Response and Greater Maximum Transmittance Modulation

By dynamically managing light and heat, electrochromic smart windows (EC-SWs) could improve energy efficiency, occupant comfort, and sustainability, resulting in more energy-efficient and environmentally friendly buildings. However, the external power-driven or solar cell-integrated EC-SW could not fulfill the modern zero energy building purpose. Although recently self-powered EC-SW windows have been invented, their low transmittance modulation and slow response time make them unsuitable for industrial use. In this study, we reported a highly efficient, simple design, and low-cost WO 3 self-powered EC window using a roll-to-roll (R2R) slot-die wet coating method where the transmittance modulation is approximately 80% at 600 nm wavelength and the spontaneous recovery time of about 60 s. The device provides around 1.2 V open circuit voltage, which is enough to power up the device itself, and thereby offers a self-powered and fast response EC-SW with high optical modulation.