Highly stable electrofluorochromic switching of aggregation-induced emission-active conjugated polymers

Abstract

The development of aggregation-induced emission (AIE) luminogens for electrofluorochromic (EFC) applications has gained traction in recent years, yet challenges such as achieving stable and reversible fluorescence switching remain. In this study, we report a series of six conjugated polymers with AIE and aggregation-induced enhanced emission (AIEE) properties, synthesized from two novel tetraphenylethylene (TPE)-based monomers designed and functionalized with diphenylamine groups in distinct vicinal and geminal configurations. These polymers exhibit reversible electrochromic (EC) switching between yellow and purple colours, coupled with efficient EFC quenching of yellow and orange fluorescence upon application of positive voltage. EFC performance evaluations show impressive fluorescence turn-off/turn-on (I_OFF/ON) ratios of up to 37.3 and exceptional switching stability, maintaining functionality across 2500 cycles. Computational analyses suggest that both Förster resonance energy transfer (FRET) and electron transfer (ET) processes are critical to the observed fluorescence quenching. These findings not only provide valuable mechanistic insights but also open new pathways for the design of AIE-active materials with enhanced EFC performance and durability for targeted real-life applications.