p-Type Dopant-Mediated Electron–Hole Recombineering to Tune the Electrochemiluminescence of Metal–Organic Frameworks

Constructing high-performance electrochemiluminescence (ECL) emitters through rational structural engineering is pivotal to overcoming the intrinsic limitations of conventional systems and advancing their practical applications. This work reports an electron-hole recombination engineering strategy to enhance the ECL emission of metal-organic frameworks (MOFs) by p-type doping of metal single-atom sites. Using Zr-TBAPy as a model, the experimental data and theoretical calculations demonstrate that the doping of single-atom Au induces notable defect energy levels, thereby providing additional recombination channels for conduction-band (CB) electrons and valence-band (VB) holes. The defect level ultimately increases the electron-hole recombination efficiency. Compared to Zr-TBAPy, single-atom Au-doped Zr-TBAPy (Au@Zr-TBAPy) exhibits a 4-fold enhancement in cathodic ECL intensity with an ECL efficiency of up to 50.56%. An ECL immunoassay was used to demonstrate the ECL application of Au@Zr-TBAPy. This work not only proposes a rational metal single-atom doping strategy for engineering ECL emitters to achieve high performance but also provides fundamental insights into the dependence of ECL emission on metal single-atom sites, opening new avenues for advanced applications of MOFs in sensitive ECL biosensing.