Endowing deep-red BODIPY luminophors with enhanced aggregation-induced emission by installing miniature rotor of trifluoromethyl for solution-processed OLEDs

Highly efficient deep-red (DR) organic materials in aggregated state are fundamentally restricted by the serious nonradiative decay rates (k nr ) due to the energy gap law, and the aggregation induced quenching in view of significant intermolecular interaction. Here, two new BODIPY chromophores owning donor−acceptor−donor (D−A−D) structure, namely CF 3 -2TPA and 2CF 3 -2TPA, were designed and synthesized. Trifluoromethyl (CF 3 )-substituted phenyl group was introduced to the meso-position of the BODIPY core, tuning red to DR emission and suppressing intermolecular interaction with the utilization of the steric hindrance of CF 3 . Besides, CF 3 -2TPA and 2CF 3 -2TPA show enhanced aggregation-induced emission (AIE) characteristic, which was ascribed to the CF 3 rotor dissipating the excited-state energy. The OLEDs are fabricated by combining a thermally assisted delayed fluorescence host with a deep-red dye, showing a DR cut-on wavelength of 668 nm and external quantum efficiency of 2.3%. This work provided a rotor strategy to convert BODIPY molecule with obvious AIE property, providing their promising applications in DR-OLEDs. The miniature rotor of trifluoromethyl (CF 3 ) introduced to the meso-position of BODIPY, induced redshifted to deep-red emission, prevented obvious intermolecular interaction and achieved remarkably enhanced aggregation induced emission feature. Deep-red OLED showed an emission wavelength of 668 nm and an EQE max of 2.3%. • The CF 3 units, modifying the meso position of BODIPY, assisted in the deep-red emission. • Depending on the steric hindrance of CF 3 groups, the intermolecular interaction and packing were suppressed. • The enhanced AIE feature of BODIPYs was realized due to the miniature rotor of CF 3 substitutes. • Deep-red OLED showed an emission wavelength of 668 nm and an external quantum efficiency of 2.3%.