Organic luminophores exhibiting both fluorescence and phosphorescence at room temperature are attractive but rare, due to the limited design strategies of room temperature phosphorescence (RTP) molecules. Here, the construction of electron donor‐acceptor‐donor (D−A−D) structure, which can afford multiple and powerful intermolecular interactions and electronic communications, is proposed as an effective method to achieve RTP. Two compounds NBCM and PBCM were designed with different electron withdrawing groups. Both exhibit efficient RTP with long lifetimes of 558 and 482 ms, as well as switchable luminescence from cyan or white to yellow, respectively. The stronger charge transfer effect and better crystallization capacity of NBCM are account for its superior RTP performance in relative to PBCM. Besides, the incorporation of pyridine endows NBCM with a special response to trifluoroacetate acid and a reversible on/off conversion of emissions. These features of NBCM pave the way to its promising applications in antifake security, encryption, fingerprint imaging and sensors.

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The development of organic luminescent materials with bimodal emissions of both fluorescence and room-temperature phosphorescent (RTP) remains a challenge. The investigation of the relationship between fluorescence and RTP performance is especially rare. In this work, we obtained an organic luminescent molecule, 1,4-phenylenebis((9H-carbazol-9-yl)methanone) (PBCM), which exhibits bimodal emissions of cyan fluorescence and yellow RTP in its crystalline state through adopting an electron donor–acceptor–donor (D–A–D) structure. The charge–transfer (CT) effects in the bimodal luminescent properties of PBCM, as well as the single-crystal structures and thermal properties, were investigated. It was found that the CT effect in the singlet states effectively reduces the ∆Est and promotes the ISC processes, resulting in an efficient phosphorescence of PBCM at room temperature. In addition, many strong intermolecular interactions are formed between the donor and acceptor parts of adjacent molecules, leading to the rigid configurations and compact packing of molecules in crystals, which was also confirmed to facilitate the efficient bimodal emissions of PBCM.