Pyrene-based blue AIEgens: tunable intramolecular conjugation, good hole mobility and reversible mechanochromism

Six blue AIEgens, including TPE-2Py(p,1), TPE-2Py(m,1), TPE-2Py(p,2), TPE-2Py(m, 2), TPE-2Py(p,4) and TPE-2Py(m,4), were designed by combining a TPE core and pyrene side groups. Modifying the linkage modes of TPE (para to meta-position) and pyrene units (1- to 2- to 4-position), their EL emissions in standard OLEDs devices were tuned from sky blue (484 nm) to deep blue (452 nm). Because of the good interaction between the pyrene side groups, the target compounds showed enhanced hole-transporting ability. When fabricated as emitters in OLEDs with or without hole-transporting layers, all the emitters exhibited blue emissions and comparable EL performances. Also, all these AIEgens showed excellent reversible mechanochromism properties with different maximum emission peaks larger than 40 nm from the crystalline to the amorphous state, offering them additional applications in the opto-electronic field.