Light on multi-mode optical properties of carbon dots through rational surface engineering tuning strategies

Carbon dots (CDs) materials are currently gaining significant attention for applications in bioimaging, fluorescent sensing, anti-counterfeiting, therapeutics, catalysis and other areas. However, efficient and attractive CDs with multi-mode luminescence and tunable spectra through simple modification strategy are still urgently needed for multifunctional optical applications and mechanism exploration. Herein, we demonstrate two rationally designed and completely different CDs surface tuning strategies, which can generate multi-mode optical properties including multi-color fluorescence (FL), room-temperature phosphorescence (RTP) and aggregation-induced emission (AIE). The optical properties after weak interactions modification are characterized by freedom and switchability, while the optical properties after strong interaction modification are characterized by compulsion and non-switchability. Moreover, it is further demonstrated that the cell imaging, light-emitting devices (LEDs), "and" logic gate and anti-counterfeiting applications based on multi-mode optical effects. This study not only provides a new model system for understanding the surface states of CDs, but also opens up opportunities for new applications of multi-mode optical materials for various purposes.