| 초록 |
Colloidal plasmonic nanocrystals have proven to be of enormous potential in a wide range of applications. Recently, active plasmon control has received intensive attention. Successful attempts to achieve plasmonic switching have been demonstrated by integrating metal nanostructures with active media whose dielectric functions can be varied by external stimuli. Electroactive materials are particularly appealing, because they allow for a fast switching of plasmon under electrochemical stimuli, opening the door to technological applications in electrochromic smart windows, three-dimensional and flat-panel displays. We have been able to coat polyaniline onto Au nanocrystals in controllable shell thicknesses. The plasmon resonance of the Au core can be modulated reversibly by varying the dielectric function of the polyaniline shell through proton doping and dedoping. A scattering intensity modulation depth of ~10 dB is obtained for the plasmonic switching on the single core@shell nanostructures. The plasmonic switching is accompanied with more than 100 nm in the reversible plasmon peak shift. We have further realized electrochemical switching. In the single-particle electrochemical switching measurements, reversible plasmonic shifts of ~20 and ~100 nm are obtained on the coated Au nanospheres and nanorods, with a remarkable stability over 200 cycles. The plasmon energy can be precisely controlled within the shift range, with the plasmonic switching time being less than 10 ms. The ensemble coated Au nanocrystals also exhibit good electrochemical plasmonic switching performances. |
