Synergistic Enhancement of Luminescent and Ferroelectric Properties through Multi-Clipping of Tetraphenylethenes

Synergistically enhancing luminescent and ferroelectric (SELF) properties are observed from a tetraphenylethene (TP) substituted with clipping groups (C), where the C is consisting of a 4-[3,5-bis-(3-decyloxy-styryl)-styryl]-phenyl (DOS) unit. The DOS units of TPCn are self-assembled via intermolecular interaction to clip themselves and induce TP aggregation, as evidenced by clip-induced quenching of emission at DOS units (E_clip) accompanied by aggregation-induced emission enhancement of TPs (E_AIE). TPC4 demonstrates strong photoluminescence in a dilute chloroform solution and large E_AIE in aqueous (>50%) THF solution. TPCn demonstrates SELF properties in film state, with high quantum yields of photoluminescence (>80%) and ferroelectric switching. Due to the introduction of four clips, TPC4 has a higher remnant polarization (P_r = 2.27 µC cm⁻²) at room temperature than TPC1. TPC4 is successfully employed in a light-emitting electrochemical cell to achieve over 1290 cd m⁻² under pulsed current conditions. The TPC4 film on a flexible substrate produced a piezoelectric output voltage of up to 0.13 V and a current density of 1.14 nA cm⁻² upon bending. These results indicate that the side chain clipping and TP aggregation resulted in unprecedented flexible SELF properties in a single compound, offering simultaneous enhancement of electroluminescence, mechanical sensitivity, and energy harvesting capacity.