No abstract

Long-term stability is a great challenge for commercializing VO 2 film, but corresponding research is lacking. This work demonstrated that the cross-section of VO 2 films is important to the corresponding deterioration process. An encapsulation structure is designed to protect VO 2 films from deterioration by utilizing stable and naturally hydrophobic HfO 2 layers. The proposed structure shows greatly extended service life, which could be equal to 16 years in the real environment. It provides a new strategy for stable VO 2 films in commercialization of applications.

Vanadium dioxide, an archetypal correlated-electron material, undergoes an insulator-metal transition near room temperature that exhibits electron-correlation-driven and structurally-driven physics. Using ultrafast optical spectroscopy and x-ray scattering we show that these processes can be disentangled in the time domain. Specifically, following intense sub-picosecond electric-field excitation, a partial collapse of the insulating gap occurs within the first ps. Subsequently, this electronic reconfiguration initiates a change in lattice symmetry taking place on a slower timescale. We identify the kinetic energy increase of electrons tunneling in the strong electric field as the driving force, illustrating a novel method to control electronic interactions in correlated materials on an ultrafast timescale.

The preparation technology and limited performance of ion conducting (IC) layers are the two main obstacles for electrochromic devices (ECDs) toward commercial application. In this work, the Li x AlO z films were fabricated by direct current (DC) magnetron sputtering with a Li–Al alloy target and show promising potential as an IC layer in ECDs owing to their high transparency, ultrahigh stability, and good ionic conductivity. The integrated all-solid-state ECDs, with the structure of ITO/NiO x /Li x AlO z /WO3/ITO, manifest less leakage current density (<10 mA/cm2), high optical regulation (ΔT = 74.4%), excellent cyclic stability (changing less than 10% after 104 cycles), and short response time (5.7 s for coloring time, 2.2 s for bleaching time). A large-scale ECD with the area of 10 × 10 cm2 was fabricated and displayed remarkable potential as a commercial application for dynamic windows.