Enhanced Room-Temperature Phosphorescence in Carbon Dots through Microwave-Assisted Aluminum-Based Surface...

Carbon dot (CD)-based room temperature phosphorescent (RTP) materials exhibit significant potential for advanced optical applications, including information encryption and anticounterfeiting. However, the rational surface engineering of CDs through the incorporation of light-metal ions to achieve an RTP emission remains a formidable challenge. Herein, we present a microwave-assisted aluminum coordination strategy that facilitates the surface polymerization of phosphorus-doped CDs, thereby achieving enhanced green RTP emission in Al³⁺-cross-linked CDs (Al-CDs) with a lifetime from 172 to 782 ms. The photophysical and structural characterizations reveal that aluminum ions coordinate with CDs, forming a cross-linked polymerized structure that effectively enhances the intersystem crossing (ISC) process, avoids aggregation-induced quenching, and suppresses nonradiative transitions. The other light-metal ions (Ca²⁺ and Na⁺) could also be coordinated with CDs through this microwave-assisted strategy, while Al-CDs exhibit better RTP properties due to the smaller energy gap between the singlet and triplet states (ΔE_ST). The mechanism of the enhanced RTP emission in the light-metal surface polymerization of CDs was further validated through systematic calculations. Due to its long-lived RTP emission and simple synthesis process, Al-CDs exhibit significant potential in the fields of information encryption and anticounterfeiting.