Proton transfer induced persistent triplet charge transfer phosphorescence in molecule-doped polymer systems

Abstract

The intermolecular interactions between small molecules and the matrix in a highly polar environment could easily lead to non-radiative transitions, which significantly hampers the development of high-performance persistent room-temperature phosphorescence (pRTP) materials in such condition. Herein, we introduce a novel strategy that integrates consecutive proton transfer and photo-induced charge transfer to facilitate triplet charge transfer emission in highly polar polymer matrix. In particular, doping aza-arene guests including 1,10-phenanthroline (1,10-Phen), 2,9-dimethyl-1,10-phenanthroline (DM-Phen), and 7,8-benzoquinoline (7,8-BQ) into polyacrylic acid (PAA) resulted in superior pRTP properties compared to other polymer hosts. Spectroscopic investigations and theoretical calculations elucidate that this is attributed to the proton transfer and triplet charge transfer characteristics between the host and guest. Moreover, due to the rigid environment and space confinement provided by PAA, pRTP with the lifetime up to 841 ms is achieved. Capitalizing on the excellent water solubility of the doped PAA films, the inkjet printings have been executed, and showcasing the promising the potential applications of these pRTP materials in the field of information encryption.