Real-time evaluation of charge transfer patterns at buried ionotronic interfaces

Abstract

Bionic and triboelectrification based ionotronics – an emerging field that bridges ions and electrons at an insulating–metallic interface – form an electric double layer (EDL), which determines charge desolation, deposition, and transfer patterns. Therefore, mechanistic evaluation of the EDL is imperative. However, the EDL forms at a unidirectional buried interface below the insulating layer, which impedes its real-time monitoring via electrochemical methods, probe microscopy, and spectral excitation. This study for the first time evaluates the EDL of ionotronics using in situ electrochemical impedance spectroscopy in conjunction with triboelectrification perturbation as an alternative to the dynamic reversible carriers of a conventional electrochemical cell. The charge dynamics at the insulating–metallic interface are elucidated through four patterns of charge transfer, charge recombination due to electrode-initiated polarity, precipitation of oppositely charged ions at the EDL, and hindered diffusion of delocalized charge. These patterns help explore neuromorphic interfaces, noise-cancellation and the intricate EDL of miniaturized robots, and enhance power sensitivity and longevity of self-powered sensors. The approach used in this work can be utilized to study a variety of buried interfaces.