Microwave-assisted establishment of efficient amorphous polymeric phosphorescent materials with ultralong blue afterglow

Abstract

Owing to distinguished characteristics such as the diverse molecular design, favorable processibility and good flexibility of non-conjugated amorphous polymeric phosphorescent materials with persistent lifetime and intensive luminescence, they have emerged as alternative candidates in various fields, thus attracting significant attention. Nevertheless, regarding the results of the investigation of non-conjugated amorphous room temperature phosphorescent materials, we found that their triplet lifespan mostly last for less than 1 s and harsh conditions and organic solvents are required for their synthesis. Herein, a concise and effective method was employed for the successful synthesis of amorphous non-conjugated polymer polyacrylamide (PAM) with efficient room temperature phosphorescence phenomenon via microwave power (MWP). The use of MWP with appropriate MWP parameters facilitated the synthesis of PAM with a persistent triplet lifetime of three phosphorescent emissions (at 414 nm, 442 nm and 462 nm) exceeding 2 s and high photoluminescence quantum yield (PLQY) of 53.8%. Different precipitation speeds resulted in various aggregated states of PAMs, and consequently different luminescence intensities and color-tunable phosphorescence properties of PAM (from blue to green) were realized through different post-processing heating temperatures. Based on this, embedding the luminophore vinyl carbazole through copolymerization with acrylamide caused copolymers to exhibit similar phosphorescent emissions as PAM and persistent triplet lifetimes reached 4.06 s, 3.89 s and 3.96 s. Benefitting from MWP, the systematic construction of amorphous polymeric RTP materials with a long triplet lifetime based on PAM provides an explicit strategy for efficient polymerization to achieve room temperature phosphorescence materials and a significant development of the applications of information protection and anti-counterfeiting.