Reversible Photochemical Switching via Plasmonically Enhanced Upconversion Photoluminescence

Photochromic molecule‐incorporated optical devices offer desirable properties for photocontrollable optical systems, including advanced optical data storage and super‐resolution imaging. However, these molecules require multiple illumination sources, such as UV and visible light, for reversible photochemical reactions, which restricts their potential for advanced application. This study reports an effective strategy for modulating photoisomerization via a single near‐infrared light source assisted by plasmonically enhanced photoswitchable upconversion photoluminescence (UCPL). The proposed quasi‐periodic metal nanostructures to facilitate the resonance modes in the broadband region enable the substitution of the detrimental high‐energy light source (i.e., UV light) with near‐infrared stimuli, which is associated with UCPL enhancement of over two orders with spectrum orthogonality. To validate this concept, the accelerated reversible‐photoisomerization kinetics is experimentally confirmed by three‐ and tenfold amplification of the PL intensities of the photochromic disulfonyldiarylethene derivatives. Further validation of the proposed strategy is performed using photodynamic imaging, which reveals accelerated photoisomerization, high photocyclization stability, and high spatial resolution. This study provides a novel strategy for effective photochemical reaction via plasmonically enhanced broadband upconversion photoluminescence (UCPL), driving simultaneous improvement of photochromic photoluminescence and accelerated switching kinetics. With highly improved broadband UCPL from UV to visible region and photoswitching performance, the assembly of photochromism and the quasi‐periodic plasmonic platform offer new opportunities in broad practical applications.