Dual-response and Li+-insertion induced phase transition of VO2-based smart windows for selective visible and near-infrared light transmittance modulation

Chromogenic materials are widely used in the field of smart window with controllable throughput of solar energy and visible light. However, single modulation mode is often difficult to meet practical applications. Herein, we construct a novel multilayer device by effectively integrating thermochromic (TC) and electrochromic (EC) materials to selectively modulate visible and near-infrared (NIR) transmittance. The all-solid-state VO2-based multilayer device consists of VO2/LiTaO3/WO3 sandwich structure, with transparent conductor FTO and ITO as bottom electrode and top electrode, respectively. Therefore, this five-layer structure realized four reversible optical states, that is, TC layer passively responds to environmental temperature, while EC layer actively responds to external voltage simultaneously. Moreover, reversible migration of Li3+ within the lattice of VO2 is achieved with a low voltage (just 3 V bias), which has an obvious effect (over 10 degrees C) on its phase change temperature (PCT). Finally, this novel dual-response VO2-based multilayer device provide a new strategy for VO2-based smart window applications.