Amorphous Room-Temperature Phosphorescence Enabled by Supramolecular Assembly and its Anti-Forgery Applications

Abstract

Room temperature phosphorescence (RTP) material has drawn extensive attention in recent years, but amorphous state RTP from purely organic molecules is rarely achieved. The strategy of supramolecular co-assembling of organic chromophore with laponite (LAP) has been utilized to achieve efficient amorphous room-temperature phosphorescence. Both experimental and theoretical investigations have demonstrated that this co-assembly not only significantly narrows the single triplet energy gap, thereby effectively facilitating the single triplet intersystem crossing (ISC) processes, but also protects the triplet state and suppresses non-radiative transitions by restricting molecular rotation and vibration through the hydrogen-bond interaction. Compared with the pristine powder, the BPBA@LAP exhibits enhanced room-temperature phosphorescence, an ultralong lifetime (1.783s) and a high phosphorescence quantum efficiency (10.3%) simultaneously. Additionally, the flexible and transparent films, produced by co-assembling BPBA@LAP with polyvinyl alcohol (PVA), demonstrate excellent phosphorescence performance. These distinctive RTP performances make them suitable for high-level information encryption applications. It is anticipated that the assembly process can be extended to fabricate other inorganic-organic room-temperature phosphorescent hybrid with smart luminescent sensitivity and anti-forgery applications.

Keywords: Room-temperature phosphorescence, Supramolecular assembly, hydrogen-bond interaction, Laponite, Temperature sensor