INFLUENCE OF THE MEDIUM ON THE ELECTROCHEMILUMINESCENT PROPERTIES OF MODIFIED ELECTRODES

This work investigates the specific influence of coreactants and background electrolytes on the electrochemiluminescent (ECL) properties of organic and perovskite luminophores. It is shown that lithium perchlorate (LiClO4), traditionally considered an inert electrolyte, is capable of inducing measurable ECL emission in 9,10-diphenylanthracene/polymethyl methacrylate (DPA/PMMA) films fabricated via the Langmuir–Blodgett technique, even in the absence of classical coreactants. Several hypotheses are proposed to explain this phenomenon, including specific interactions of Li+ cations with the π-system of DPA and the possible stabilization of radical intermediates, highlighting the non-inert role of lithium salts in ECL processes. In parallel, the ECL response of CsPbBr3 perovskite films in the presence of persulfate (S2O82-) as a cathodic coreactant was studied. Two ECL generation processes separated by potential were identified. It was established that the intrinsic ECL of perovskites exceeds the background emission of persulfate, and is characterized by stability and reproducibility over more than 30 electrolysis cycles. Morphological studies revealed surface changes of the films during electrolysis, correlating with the dynamics of the signal. Spectral analysis confirmed the difference between the two processes and revealed partial overlap of the electrolyte emission with the perovskite luminescence, enabling resonance signal enhancement. Furthermore, the influence of oxygen was established, modulating the intensity and stability of ECL. The obtained results demonstrate the critical role of the electrolyte, interfacial processes, and film morphology in the formation of ECL, opening prospects for the development of sensitive and stable luminescent platforms for analytical and biosensing applications.