Phosphine‐Manipulated p‐π and π‐π Synergy Enables Efficient Ultralong Organic Room‐Temperature Phosphorescence

Organic room temperature phosphorescence (RTP) attracts extensive attentions, but still faces the challenge of achieving both high RTP efficiencies (ηRTP ) and long lifetimes (τRTP ), due to the intrinsic contradiction between triplet radiation and stabilization. In this work, we developed three carbazole-triphenylphosphine hybrids named xCzTPP, in which phosphine groups provide nonbonding electrons and steric hindrance to modulate intermolecular p-π and π-π interactions. With the rational orientations and spatial positions of functional groups, para-substituted pCzTPP achieves high ηRTP over 10 % and more than twofold increased τRTP (>600 ms), compared to ortho- and meta- isomers. Theoretical simulation and photophysical investigation indicate that the strongest intermolecular p-π and π-π electronic interplays of pCzTPP harmonize high transition probability of 3 pπ state and triplet stability of 3 ππ state, reflecting the p-π and π-π synergy in RTP process.