Regulation of various photo-active UOPs in a polymer matrix by tuning intermolecular charge transfer

Abstract

Polymer-based ultralong organic phosphorescence (UOP) materials have attracted considerable attention due to their characteristics of simple process, low cost, large-scale preparation and stable performance. However, organic phosphorescent emitters capable of exhibiting ultralong afterglow in different polymer matrices have been seldom reported. Two phosphorescent emitters of carbazole derivatives, CzPN and CzBN, have been synthesized and doped into poly(methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) matrices. It was found that all four of the prepared polymer films could exhibit ultralong afterglow. Unusually, CzBN and CzPN showed intense afterglow in the PVA matrix without UV pre-excitation, lasting up to 10 s and 6 s, respectively. In contrast, the CzBN@PMMA and CzPN@PMMA films needed to undergo a photo-active process. Interestingly, the photo-active time of CzBN@PMMA was significantly longer than that of CzPN@PMMA films. The molecular oxygen in the PMMA matrix and the wrapping effect of the PVA chains led to polymer-based afterglow materials with different photostimulation responsiveness. This work offered guidance on tuning the photo-active process of phosphorescent materials and paved the way for the future development of more functionally diverse polymer-based afterglow materials.