Near‐Infrared Organic Ultralong Room‐Temperature Phosphorescence Materials Constructed via Multiple Phosphorescence Resonance Energy Transfer
Longyue Yu, Ning Feng, Wenwen Fu, Xionghui Huang, Xin Li, Xia Xin, Jingcheng Hao, Hongguang Li
Abstract
Abstract Organic ultralong room‐temperature phosphorescence (OURTP) materials with white and near‐infrared (NIR) emission have unparalleled advantages in information encryption, bio‐imaging, and materials science. However, limited by the energy gap law, the NIR OURTP materials (exceeding 700 nm) are very rare, furthermore, these materials typically exhibit very brief phosphorescence lifetimes. Therefore, there is an urgent need to find methods to achieve NIR afterglow emission with ultralong lifetimes from organic chromophores. Here, a universal strategy has been proposed to endow polymeric afterglow materials with wide color, ultralong lifetimes, and persistent NIR emission based on multiple sequential phosphorescence resonance energy transfer (P‐FRET). The poly(acrylamide‐co‐N‐vinylcarbazole) (PAMCz) with blue‐emission OURTP act as the energy donor while traditional highly fluorescent dyes (BODIPY derivatives, rhodamine b (RhB) and sulfo‐cyanine5 (Cy5)) with green/red/NIR fluorescence act as the energy acceptor. Significantly, the multi‐pathway sequential P‐FRET shows distinct advantages over single‐path sequential PRET, including higher antennae effect (AE), a broader spectrum of color‐tunability facilitated by the intermediary acceptor, and improved phosphorescence intensity and lifetimes of the terminal acceptor. By simply regulating the doping composition and concentration of these acceptors, a perfect white‐emission with CIE coordinate (0.336, 0.330) and persistent NIR‐emission with 2.7 s phosphorescence lifetimes are successfully realized.