Phosphorescent carbon dots: Intermolecular interactions, properties, and applications

Room-temperature phosphorescence (RTP) materials show promising potential across diverse domains. Carbon dots (CDs), as an emerging category of RTP materials, have garnered significant attention owing to their remarkable optical properties, cost-effectiveness, non-toxicity, and commendable biocompatibility. Recent studies have demonstrated that manipulation of intermolecular interactions, such as the hydrogen bonds, covalent bonds, aggregation-induced effect, ionic bonds, and halogen bonds, can effectively suppress non-radiative transitions and minimize the influence of oxygen on phosphor to achieve diverse types of efficient CD-based RTP materials. Additionally, intermolecular interactions involving halogen atoms and heteroatoms also facilitated the RTP emission of CDs by enhancing intersystem crossing (ISC) of the triplet excitons. Significant progress has been achieved in the advancement of CD-based RTP materials through the comprehensive implementation of the aforementioned strategies. Nevertheless, there remains a limited scope of related investigations and a dearth of systematic reviews exploring the connection between intermolecular interactions and RTP properties. In this review, we presented a comprehensive summary of recent studies conducted on CD-based RTP materials, encompassing the elucidation of RTP mechanisms, manipulation of intermolecular interactions, modulation of RTP properties. Moreover, the potential applications of phosphorescent CDs in information security, sensing, biomedicine, and light-emitting diode devices were further discussed. Finally, we proposed a myriad of meticulous perspectives regarding the design of materials, exploration of mechanisms, modulation of properties, and further development of applications in the fervent hope of offering a priceless direction for the future advancement of RTP materials based on CDs.