Exploration And Development Of Novel Self-powered Electrochromic Material And Device

Self-powered electrochromic device represents a special kind of smart window, which can change transmittance using electrical energy that itself converted from solar energy. In this area, most researches are based on inorganic materials and solar cell technology, which lead to a slow switching speed and low contrast in different states. During my graduate study, I focus on how to achieve a novel self-powered electrochromic material and device. The main research wroks are as follows:We first designed and fabricated a novel self-powered electrochromic window based on electrochromic polymer and ruthenium complex together with LiI/I2.The device can change its color by switching the state of the external circuit under illumination, without any external power. It shows fast switching speed and high contrast in the visible region.As the electrolyte based on LiI/I2shows its natural deep brown color, which makes self-powered electrochromic device performing a low transmittance in bleached state. We synthesized several colorless organic redox couple electrolytes, and these electrolyte can improve the transmittance of self-powered electrochromic device in bleached state.To achieve a kind of material which can realize dual functions of electrochromic and solar-energy conversion, we designed and synthesized a new molecule based on triphenylamine. The material performs the two functions as we expected while absorbed on titanium dioxide nano-particle. This material is a good candidate for designing and developing new self-powered electrochromic devices.To improve the stability and life time of electrochromic device,2-thienyl phosphonic acid and2-thiophene carboxylic acid were used to modify ITO substrate. Optical and electrical properties of the modified substrates had little change compared with bare one. Furthermore, the modification greatly improves the stability and electrochromic response of the electrochromic films deposited on these modified substrates. Electrochromic device based on modified ITO performed fast color-changing speed and a good stability even after cycling for350,000times.