Silver Doping Boosts Electrochemiluminescence of Copper Nanocluster Assemblies

Developing highly efficient electrochemiluminescence (ECL) emitters from copper nanoclusters (CuNCs) remains a significant challenge. This work reports the synthesis of silver (Ag)-doped Cu nanocluster assemblies (CuAgNCsAssy) on a large scale, which exhibit a 10-fold enhancement in ECL efficiency compared to the undoped counterpart. Computational and experimental studies are combined to gain insight into the intrinsic mechanism for the ECL improvements with Ag-doping. The results demonstrated that Ag doping strategically induces ground-state structural distortion in CuAgNCsAssy. This distortion enhances the polarity of metal sites, facilitating the key process of coreactant (triethylamine) radical absorption and accelerating electron transfer. Furthermore, Ag doping suppresses excited-state structural relaxation, leading to boosted radiative emission, which also promotes efficient energy transfer processes and extends radiative lifetime. As a proof of concept, an ECL aptamer sensor was constructed for detecting human epidermal growth factor receptor 2 (HER2) protein with high sensitivity. Leveraging the specific interactions between sulfhydryl groups and silver ions during post-treatment, the sensor achieves a superior detection limit.