How to utilize molecular vibration to tune triplet-involved emissions in multiple states is highly challenging. Here, star-shaped triphenylamine derivatives have been employed as model systems to understand how molecular vibration affects thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) emissions in multiple states. Nonplanar, star-shaped conformations allow molecules to generate appropriate vibrations in the solution state, facilitating vibronic coupling between their T1 and T2 states to generate effective TADF. More importantly, a relatively dispersed state can allow the molecules to efficiently vibrate in the solid state, and a crystalline environment further promotes a more efficient TADF. Lastly, by suppressing molecular vibration to inhibit the TADF, ultra-long RTP was observed upon doping these molecules into polymers. These molecules can be used in information encryption and storage as well as bioimaging.
Keywords: Anti-Counterfeiting; Bioimaging; Room Temperature Phosphorescence; Thermal Activation Delayed Fluorescence; Vibronic Coupling.
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