Highly Efficient Deep‐Blue Room‐Temperature Phosphorescence With Tunable Long‐Lived Afterglow and Reversible Photoactivation Behavior

ABSTRACT Wide band gap organic molecule with ultralong room‐temperature phosphorescence (RTP) remains a big challenge in optoelectronic field due to the intrinsic large Stokes shift of phosphorescence relative to fluorescence, and complexity of filling and stabilizing high‐energy triplet excited states. In this work, three organic small molecules, MSPA , BSPA , and TSPA , based on succinimide and triphenylamine groups are designed and synthesized, and deep‐blue RTP with reversible photoactivation properties is successfully realized by physically doping them into polyvinyl alcohol (PVA) matrix. Notably, MSPA ‐doped film exhibits RTP at 440 nm with ultralong lifetime of 1403 ms and phosphorescence quantum yield as high as 14.32%. Theoretical calculations reveal that the efficient intersystem crossing and strong intermolecular hydrogen‐bonding interactions leads to the ultralong RTP in MSPA /PVA doping system. Taking advantages of the wide band gaps, tunable organic afterglow, and reversible photoactivation behaviors of MSPA , BSPA , and TSPA , the amorphous and flexible films are prepared and show potential applications in photoactivated information encryption, advanced anti‐counterfeiting, and multicolored displays through triplet‐to‐singlet Förster energy transfer. This work provides a reliable strategy to realize high‐performance wide band gap RTP materials and further broadening practical applications in organic optoelectronic information.