Multi‐Hydrogen Bonds Enhanced Anchoring Effect Enabling High‐Efficiency Blue Phosphorescence, Single‐Molecule White Light, and Tunable Colorful Emission with Quantitative Energy Transfer

Abstract Ultralong organic room‐temperature phosphorescence (RTP) materials, especially high‐energy blue emission materials, have attracted tremendous attention but remain difficult to achieve. Here, a strategy based on the multi‐hydrogen bonds enhanced anchoring effect is developed to activate single‐molecule blue phosphorescence emission with the highest efficiency of 29.79%. Specifically, the aromatic electrophilic directing (AED) effect provides a rational explanation for the structural spectral change. The construction of artificial light‐harvesting systems via physical blending achieves on‐demand modulation for afterglow color, including white afterglow. Furthermore, cold‐white emission is also achieved via a structural π‐extension optimization strategy. Moreover, the high transmittance and reversible water‐sensitivity render these polymer films with applicability as smart organic optoelectronic materials.