Influence of chemical treatment and interaction with matrix on room temperature phosphorescence of carbon dots.

In this work, composite materials were formed based on various matrices (polymer and porous cellulose matrix) and carbon dots (CDs) with intense room temperature phosphorescence (RTP). The effect of postsynthesis chemical treatment with citric acid or urea on the optical properties of composites was studied: the increase in carboxy and carbonyl groups lead to an increase of RTP signal which can be seen with the naked eye over several seconds. Fabricated composites demonstrate good stability and reversibility of RTP signal by mild heating. Based on developed CDs, luminescent inks were used for simple demonstration of the data encryption on a paper.