Molecular Engineering of Polymer Dots for Electrochemiluminescence Emission

Aggregation-induced emission (AIE) has attracted considerable attention in designing high-performance emitters for both photoluminescence (PL) and electrochemiluminescence (ECL). In this study, to prepare AIE-active polymer dots (Pdots) with efficient PL and ECL emission, we demonstrate a molecular engineering strategy by tuning the side chain of fluorenyl–tetraphenylethylene polymers from ester to carboxyl groups. By introducing the carboxyl group at a moderate fraction, significant PL enhancement was achieved, benefiting from the more quantities and the better compactness of the luminophores inside the Pdots. The ECL emission of these carboxylic Pdots has also been promoted to a highest quantum yield (ΦECL) of 54.7%, making it a promising ECL emitter for visual detection for bioanalysis. Unlike the traditional oxidative–reductive mechanism, the ECL of carboxylic Pdots exhibited a unique low-oxidation-potential (LOP) route that originated from the enhanced proton-coupled electron transfer (PCET) within the carboxylic nanoparticles.