Room‐Temperature Phosphorescent Film Materials: N−C═O Resonance‐Driven Heavy‐Atom‐Free Design and Triplet Harvesting

Abstract Room‐temperature phosphorescent (RTP) materials can produce long‐lived luminescence at room temperature, which breaks through the dependence of traditional phosphorescent materials on low‐temperature conditions and shows great potential in the fields of information encryption, bio‐imaging, and optical sensing. However, the realization of long‐lived and high‐efficiency phosphorescence in organic materials at room temperature still faces severe chal8lenges, which are mainly attributed to the enhancement of molecular nonradiative transitions, the inefficiency of intersystem crossing (ISC), and the bursting effect of oxygen on triplet excitons at room temperature. In this study, RTP material with N─C═O resonance structure was synthesized by reacting 2,3‐diaminonaphthalene and 4‐methoxybenzoyl chloride as raw materials. A polymer matrix doping strategy was adopted to dope the prepared materials with PMMA in different weight ratios in order to achieve high efficiency and long lifetime room temperature phosphorescence emission. Experimental results demonstrate that upon incorporation of PMMA, the previously inactive material exhibits intense photoactivated persistent luminescence. The nonradiative relaxation was suppressed by the domain‐limiting effect.