Aromatic Amides: A Smart Backbone toward Isolated Ultralong Bright Blue‐Phosphorescence in Confined Polymeric Films

Abstract We describe an aromatic amide skeleton for manipulation of triplet excited states toward bright long‐lived blue phosphorescence. Spectroscopic studies and theoretical calculations demonstrated that the aromatic amides can promote strong spin‐orbit coupling between (π,π*) and the bridged (n,π*) states, and enable multiple channels to populate the emissive 3 (π,π*), as well as facilitate robust hydrogen bonding with polyvinyl alcohol to suppress non‐radiative relaxations. Isolated inherent deep‐blue (0.155, 0.056) to sky‐blue (0.175, 0.232) phosphorescence with high quantum yields (up to 34.7 %) in confined films are achieved. The blue afterglow of the films can last for several seconds and are showcased in information display, anti‐counterfeiting, and white light afterglow. Owing to the high population of 3 (π,π*) states, the smart aromatic amide skeleton provides an important molecular design prototype to manipulate triplet excited states for ultralong phosphorescence with various colors.