Energy Level Engineering in Gold Nanoclusters for Exceptionally Bright NIR Electrochemiluminescence at a Low Trigger Potential

Electrochemiluminescence(ECL) is a widely used lightoutput mechanismfrom electrochemical excitation. Understanding the intrinsic essencefor ideal ECL generation remains a fundamental challenge. Here, basedon the molecular orbital theory, we reported an energy level engineeringstrategy to regulate the ECL performance by using ligand-protectedgold nanoclusters (AuNCs) as luminophores and N,N-diisopropylethylamine (DIPEA) as a coreactant. The energylevel matching between the AuNCs and DIPEA effectively promoted theirelectron transfer reactions, thus improving the excitation efficiencyand reducing the trigger potential. Simultaneously, the narrow bandgap of the AuNCs further enabled enhanced emission efficiency. Usingthe energy level engineering theory developed here, a dual-enhancedstrategy was proposed, and & beta;-CD-AuNCs were designed to furtherverify this mechanism. The & beta;-CD-AuNCs/DIPEA system resultedin highly stable near-infrared ECL with an unprecedented ECL efficiency(145-fold higher than that of the classic Ru(bpy)(3) (2+)/tetra-n-butylammonium perchlorate system)and a low trigger potential of 0.48 V. A visual NIR-ECL based on thisECL system was successfully realized by an infrared camera. This workprovides an original mechanistic understanding for designing efficientECL systems, which promises to be a harbinger for broad applicabilityof this strategy for other ECL systems and ECL sensing platforms.

Automated summary

In this study, an energy level engineering strategy was proposed to regulate the electrochemiluminescence (ECL) performance using ligand-protected gold nanoclusters (AuNCs) as luminophores and N,N-diisopropylethylamine (DIPEA) as a coreactant. The energy level matching between the AuNCs and DIPEA effectively promoted electron transfer reactions, improving excitation efficiency and reducing trigger potential. The narrow bandgap of the AuNCs further enhanced emission efficiency. The developed theory was successfully applied to design a highly stable near-infrared ECL system with low trigger potential.