Multicolor Electrochromism via Plasmonic Tuning in Au NBPs@PANI Nanostructures with Ultrafast Switching and Enhanced Bistability

Abstract Gold nanobipyramids (Au NBPs) exhibit pronounced localized surface plasmon resonance (LSPR) properties, demonstrating the significant potential for diverse photonic applications. However, they are constrained to static plasmonic structural color displays, significantly limiting their practical utility. Herein, an innovative approach is presented for dynamically regulating the structural colors of gold nanoparticles through electrochemical manipulation. By precisely controlling the redox state of the polyaniline (PANI) nanoshell coating on Au NBPs@PANI core–shell structures, tunable shifts in the LSPR peak position of Au NBPs are achieved, consequently enabling precise color modulation. Through systematic optimization of PANI deposition cycles, an optimal PANI shell thickness of 25 nm is identified for enhanced performance. The engineered Au NBPs@PANI composite demonstrates remarkable electrochromic properties, exhibiting reversible transitions among three distinct colors (green, cyan, and blue) with an ultrafast switching speed of 100 ms and exceptional cycling stability (maintaining consistent absorbance characteristics through 200 switching cycles). Furthermore, the system exhibits excellent bistability, maintaining its chromatic state for over 30 min after voltage removal, thereby significantly reducing energy consumption. This research establishes a cost‐effective, scalable fabrication and performance optimization strategy for advanced electrochromic materials, offering promising technical support for energy‐efficient electronic paper displays and related photonic applications.