Organic NIR afterglow with emission wavelengths beyond 800 nm

Organic near-infrared (NIR) afterglow has considerable potential for bioimaging applications owing to its deep penetration depth and high signal-to-background ratio (SBR). However, achieving organic afterglow with emission wavelengths above 800 nm is still a significant academic challenge because of the limitations of the energy gap law. Herein, bright NIR afterglow with a wavelength of 820 nm was realized via an intelligent molecular design strategy: alternating electronic donor-acceptor (D-A) structures and multiple S⋯O intramolecular interactions were utilized to enhance the intramolecular charge transfer (ICT) effect and strengthen intramolecular interactions. Additionally, terminal groups and side chains optimize the intermolecular interactions among luminogens to suppress nonradiative transitions. This work provides a promising strategy to achieve efficient NIR afterglow, further promoting its potential applications in bioimaging with deep tissue penetration and high SBR.