Electrically switchable metallic polymer metasurface device with gel polymer electrolyte

Abstract

We present an electrically switchable, compact metasurface device based on the metallic polymer PEDOT:PSS in combination with a gel polymer electrolyte. Applying square-wave voltages, we can reversibly switch the PEDOT:PSS from dielectric to metallic. Using this concept, we demonstrate a compact, standalone, and CMOS compatible metadevice. It allows for electrically controlled ON and OFF switching of plasmonic resonances in the 2–3 µm wavelength range, as well as electrically controlled beam switching at angles up to 10°. Furthermore, switching frequencies of up to 10 Hz, with oxidation times as fast as 42 ms and reduction times of 57 ms, are demonstrated. Our work provides the basis towards solid state switchable metasurfaces, ultimately leading to submicrometer-pixel spatial light modulators and hence switchable holographic devices.

Plasmonic polymer nanoantenna arrays for electrically tunable and electrode-free metasurfaces

“…This device structure enables much simpler fabrication processes because all layers can be formed in-plane without the need for complicated sandwich structures. More importantly, compared with the previously reported ion-gel-based devices, 17,18 light passing through the PEDOT:Sulf structures does not have to encounter additional electrodes (e.g. an ITO layer) or contacts which are typically opaque and hinder the mid-infrared operation.…”

“…Note that the overall qualities of the nanoantennas, such as size controllability or sharpness of the edges, obtained by SANE-RIE exceed those from colloidal lithography 14,18 and are almost comparable to those from electron-beam lithography. [15][16][17] This can be partly attributed to the fact that the patterned photoresist using SANE has well-dened sidewalls compared to the polystyrene nanospheres used as masks in colloidal lithography.…”

“…[9][10][11][12][13] Recently, highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) based polymer nanoantennas have shown unique potential as a building block of electrically tunable metasurfaces working in the infrared spectral range. [14][15][16][17][18][19] Therein, the redox states of the PEDOT nanoantennas were controlled by electrochemical doping and dedoping, resulting in changes in both charge carrier concentration and mobility, and consequently nanooptical responses. 18 Tunable metasurfaces using polymeric materials will be benecial for low-cost and low-power applications working in the infrared region, such as smart windows, at optical components, and surface-enhanced molecular sensors.…”

“…18,20,21 However, although the plasmon resonances of the PEDOT nanoantennas can reach the mid-infrared region (>3 mm), 14 the operating wavelength of electrically tunable PEDOT metasurface devices has so far been limited to the near-infrared region (<3 mm). [15][16][17][18] In order to apply voltages to the individual isolated nanoantennas, an additional supporting electrode underneath them, such as an indium tin oxide (ITO) layer, has been inevitable. However, such electrodes are usually not transparent close to the mid-infrared region, which hinders operation in the full spectral region available by the materials.…”

“…To our knowledge, only two types of nanofabrication methods, each with its own strengths and weaknesses, have been reported. On the one hand, electron beam lithography has shown great promise in the fabrication of complicated metasurfaces, [15][16][17] but the cost of this technique overshadows the potential commercial application of its products. On the other hand, colloidal lithography provides a cost-effective means to achieve large-area polymer metasurfaces, 14,18 but the positions and shapes of nanoantennas cannot be precisely controlled, making it unsuitable for the fabrication of phase-gradient metasurfaces or systems requiring long-range order.…”