Probing of Carrier Motion and Contact Electrification by Using Electric-Field-Induced Second-Harmonic Generation

Abstract

Triboelectric generation has attracted significant interest for its potential as an eco-friendly way to produce power with a greatly increasing power density, thereby opening the door to various applications. Although the triboelectricity effect is one of the oldest research areas and an enormous amount of effort has been put forth in developing it for many applications, its physical origin remains a mystery. Particularly, the complexity of triboelectrification causes the motion of charge carriers, including charge generation, charge separation, and other charging processes, to be vague. A novel approach based on optical second-harmonic generation technology has shown great promise in directly monitoring the dynamic performance of the triboelectricity effect and hence visualizing the spatial distribution of triboelectric charges. In this article, several works on the direct probing of carrier motion in organic transistors and in bulk heterojunction organic solar cells and of contact electrification by using an optical second-harmonic generation technique will be briefly introduced and discussed after second-harmonic generation and electric-field-induced second-harmonic generation have been described.