Lifetime-tunable organic persistent room-temperature phosphorescent salts for large-area security printing

Organic persistent room-temperature phosphorescent (RTP) materials are promising for applications requiring the secure recording and anti-counterfeiting features owing to their appealing optical properties. Several critical challenges, such as difficulty obtain high-quality patterns over large areas low security levels, need be addressed meet requirements commercial purpose. Here, we prepared a series of quaternary phosphonium salts with different alkyl chains, which showed interesting organic RTP. The ionic characteristics chains these molecules impart abundant weak intermolecular interactions. This confers high crystallinity, helps preserve RTP properties cover areas. Moreover, lifetime varies wide range (1.27 884.71 ms) can tuned by simply changing chain length counterions, opens new possibilities in multi-level information encryption applications. It is believed that engineering tunable lifetimes large-area printing promote early-stage demonstrations into mature commercialization.