Controllable Phase Transition Properties in VO<sub>2</sub> Films via Metal-Ion Intercalation.

He, Zihao; Qi, Zhimin; Yang, Bo; Lu, Ping; Shen, Jianan; Dilley, Neil R; Zhang, Xinghang; Wang, Haiyan · Nano Lett · 2023

basic_science · Level V

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Abstract

VO<sub>2</sub> has shown great promise for sensors, smart windows, and energy storage devices, because of its drastic semiconductor-to-metal transition (SMT) near 340 K coupled with a structural transition. To push its application toward room-temperature, effective transition temperature (<i>T</i><sub>c</sub>) tuning in VO<sub>2</sub> is desired. In this study, tailorable SMT characteristics in VO<sub>2</sub> films have been achieved by the electrochemical intercalation of foreign ions (e.g., Li ions). By controlling the relative potential with respect to Li/Li<sup>+</sup> during the intercalation process, <i>T</i><sub>c</sub> of VO<sub>2</sub> can be effectively and systematically tuned in the window from 326.7 to 340.8 K. The effective <i>T</i><sub>c</sub> tuning could be attributed to the observed strain and lattice distortion and the change of the charge carrier density in VO<sub>2</sub> introduced by the intercalation process. This demonstration opens up a new approach in tuning the VO<sub>2</sub> phase transition toward room-temperature device applications and enables future real-time phase change property tuning.