Electrochromic properties of chemically prepared polyaniline

Electrochemically controlled metasurfaces with high-contrast switching at visible frequencies

Recently in nanophotonics, a rigorous evolution from passive to active metasurfaces has been witnessed. This advancement not only brings forward interesting physical phenomena but also elicits opportunities for practical applications. However, active metasurfaces operating at visible frequencies often exhibit low performance due to design and fabrication restrictions at the nanoscale. In this work, we demonstrate electrochemically controlled metasurfaces with high intensity contrast, fast switching rate, and excellent reversibility at visible frequencies. We use a conducting polymer, polyaniline (PANI), that can be locally conjugated on preselected gold nanorods to actively control the phase profiles of the metasurfaces. The optical responses of the metasurfaces can be in situ monitored and optimized by controlling the PANI growth of subwavelength dimension during the electrochemical process. We showcase electrochemically controlled anomalous transmission and holography with good switching performance. Such electrochemically powered optical metasurfaces lay a solid basis to develop metasurface devices for real-world optical applications.

Synthesis and electronic properties of 3,7-dianilino substituted N-hexyl phenothiazines

3,7-Diaminophenothiazine derivatives are readily synthesized via two-fold Buchwald-Hartwig coupling of 10-hexyl 3,7-dibromo-10H-phenothiazine with a series of primary and secondary anilines and amines. All derivatives possess two reversible oxidations at low potentials with remarkable semiquinone formation constants. The electronic structure of this novel class of phenothiazinyl-oligoanilines is additionally studied and rationalized by DFT computations and correlation studies between selected experimental and computational electronic data.