Modulating the electronic structure of a semiconductor to optimize its electrochemiluminescence performance

Electrochemiluminescence (ECL) is a light emission process originating from the energy relaxation of excited chemical states. For semiconducting materials, the ECL performance highly depends on the electronic band structure and the relaxation dynamics of charge carriers in excited states. Even though extensive investigations have been attempted, how the electronic structure relates to and affects the final ECL performance has not been fully understood thus far. Here, using carbon dots (CDs) as a model system, we reported the electrochemiluminescence (ECL) of carbon dots with different nitrogen doping concentrations obtained via a hydrothermal method. Nitrogen doping tuned the electronic structure of the carbon dots, resulting in a broadened band gap and slower decay dynamics. These two aspects restrained nonradiative recombination and promoted radiative recombination, which ultimately enhanced the ECL performance.