1690-Fold enhanced electrochemiluminescence of gold nanoclusters via Zn²⁺ induced aggregation

Herein, a zinc ion (Zn²⁺)-induced aggregation strategy is proposed for 1690-fold enhanced electrochemiluminescence (ECL) from d-penicillamine (DPA)-capped gold nanoclusters (AuNCs), and the aggregation-induced ECL (AIECL) is a multiplicative effect of two enhancing factors. One is the improved ligand rigidification of Zn²⁺-induced aggregation of AuNCs, i.e. Zn²⁺-AuNCs. The Zn²⁺ of Zn²⁺-AuNCs can reduce the vibration and rotation of DPA, suppress non-radiative decay, and result in ∼17-fold enhanced emission with photoluminescence (PL) as control. The other is the promoted electron transfer by Zn²⁺-DPA bonds, which can enhance charge annihilation with the assistance of energy level alignment between AuNCs and the Zn²⁺-DPA bond, further amplifying ECL by another ∼100-fold. The dual-enhanced AIECL strategy can be utilized to design even brighter ECL luminophores.