Carbon dots confined in Y(OH)3 matrix with room temperature phosphorescence for information security applications

Carbon dot (CD)-based room-temperature phosphorescent (RTP) materials have aroused wide attention owing to their excellent photophysical properties. However, the reports of RTP CDs in information encryption and erasure applications are limited. Herein, a new-type of CD-based RTP material is constructed by incorporating the fluorescent CDs into yttrium hydroxide matrix (CDs@Y(OH) 3 ). For the first time, the Y(OH) 3 as a rigid matrix is used to stabilize the triplet state of the CDs and protect the CDs from oxygen. Furthermore, the intramolecular motions of the CDs are limited, due to the space confinement of the Y(OH) 3 matrix and the formation of hydrogen bonds, thus effectively suppressing the non-radiative transition of triplet excitons and promoting phosphorescence emission. Based on superior optical performance, the CDs@Y(OH) 3 composites are successfully applied in information encryption, and decryption. In addition, by destroying the Y(OH) 3 matrix with acetic acid spray, the phosphorescence is invalidated and the information is erased after decryption. This finding not only provides a new strategy for the preparation of CD-based RTP materials but also reveals the great potential of CDs in information security and protection.