Dynamically Tunable Localized Surface Plasmon Resonance in Self‐Assembled SrCoOx‐Au Vertically Aligned Nanocomposite Thin Films

While the physical principles for regulating localized surface plasmon resonance (LSPR) are well established, dynamically tuning the LSPR in a given material post synthesis remains challenging. Herein, this study demonstrates a strategy for dynamically tuning the LSPR of Au nanostructures by selectively altering the dielectric environment. Au is integrated with an electrochemically gatable oxide, i.e., SrCoOx (SCO), into vertically aligned nanocomposite thin films via a self‐assembly growth mechanism, where Au develops into nanopillars embedded in the SCO matrix. By selectively controlling the tri‐state phase transitions of SCO matrix via varying the bias voltage polarity in ionic liquid gating (ILG), the LSPR behavior of Au nanopillars can be dynamically tuned. Specifically, gating with a negative bias fully suppresses the LSPR, while a positive bias leads to a continuous blueshift of the LSPR wavelength upon increasing the ILG duration. This work not only opens new directions for the dynamic control of LSPR of noble metal nanostructures, but also offers insight to the voltage control of multifunctionalities via structural and physical intercoupling between different phases in self‐assembled nanocomposites. Au is integrated with electrochemically gatable oxide SrCoOx (SCO) into vertically aligned nanocomposite thin films. Through ionic liquid gating induced phase transitions in SCO, the LSPR of Au can be dynamically tuned: negative gatings completely suppress the LSPR, while positive results in a continuous blueshift of the LSPR wavelength with the gating duration increasing.