Abstract
Devices: Printing vanadium dioxide switches Vanadium dioxide switches are screen printed in a high-throughput process. Vanadium dioxide is an attractive material for electrical devices as it displays a metal-insulator transition that can be controlled by thermal, optical, and electrical stimuli. However, producing vanadium dioxide devices over large areas and in high quantities is challenging. Here, a team from King Abdullah University of Science and Technology led by Prof. Atif Shamim reports a microparticles-based vanadium dioxide ink suitable for screen-printing. They print switches onto rigid and flexible substrates, achieving a high ON/OFF ratio of 300 and a low ON resistance of 1.8 ohm. After integrating the switches into band-stop filters and band-pass filters, the operation frequency of the filters can be reconfigured. This work demonstrates the possibility of printing vanadium dioxide for large-scale electronic devices.
Smart materials that can change their properties based on an applied stimulus are in high demand due to their suitability for reconfigurable electronics, such as tunable filters or antennas. In particular, materials that undergo a metal-insulator transition (MIT), for example, vanadium dioxide (VO2) (M), are highly attractive due to their tunable electrical and optical properties at a low transition temperature of 68 degrees C. Although deposition of this material on a limited scale has been demonstrated through vacuum-based fabrication methods, its scalable application for large-area and high-volume processes is still challenging. Screen printing can be a viable option because of its high-throughput fabrication process on flexible substrates. In this work, we synthesize high-purity VO2(M) microparticles and develop a screen-printable VO(2)ink, enabling the large-area and high-resolution printing of VO(2)switches on various substrates. The electrical properties of screen-printed VO(2)switches at the microscale are thoroughly investigated under both thermal and electrical stimuli, and the switches exhibit a low ON resistance of 1.8 ohms and an ON/OFF ratio of more than 300. The electrical performance of the printed switches does not degrade even after multiple bending cycles and for bending radii as small as 1 mm. As a proof of concept, a fully printed and mechanically flexible band-pass filter is demonstrated that utilizes these printed switches as reconfigurable elements. Based on the ON and OFF conditions of the VO(2)switches, the filter can reconfigure its operating frequency from 3.95 to 3.77 GHz without any degradation in performance during bending.