Achieving room temperature phosphorescence in aqueous phase through rigidifying the triplet state and information encryption

Room temperature phosphorescence materials show promising prospect in various fields, howbeit, it is difficult to overcome their unstable triplet state originated from dissolved oxygen, resulting in the challengeable synthesis of water-resistance room temperature phosphorescence materials. Here, we raised a facile strategy to originally prepare one kind of carbon dots (CDs) with blue fluorescence, and their phosphorescence with a high quantum yield of 23% is further activated in aqueous environment by forming the hydrogen bonds mediated complex between carbon dots and cyanuric acid (CA-CDs). Importantly, the bridge-like hydrogen bonds not only ensure the rigidify of the triplet state of CDs but also isolate oxygen, thus facilitating a small energy gap of 0.44 eV between the singlet and triplet states of CA-CDs, which provided the evidence for understanding the RTP appearing by another innovative way. Relying on their dual-emission behavior, the current RTP CA-CDs were successfully applied for the fingerprint recognition and advanced information encryption.

Automated summary

The study presents a method to activate room temperature phosphorescence of carbon dots in aqueous environment by forming a hydrogen bond-mediated complex with cyanuric acid, which expands their application potential and provides new insights into the luminescence mechanism.