Plasmon-Induced Simultaneous Electrochemical and Fluorescence Switches Probed by Combined SECM and Fluorescence Microscopy

An unprecedented dual simultaneous switch of fluorescence intensity and electrochemical current induced by plasmon activation is demonstrated using a combination of electrochemical (SECM) and fluorescence microscopies with a fluorescent redox-active probe (tetrazine derivative) in solution. The mechanism of this dual switch is assigned to an asymmetric charge injection involving holes rather than electrons, despite the oxidant character of the redox probe. Thermal effects due to plasmon activation have been measured by using quantitative phase imaging and revealed negligible solution temperature increases, corroborating the main role of charge injection. This demonstrates for the first time that electrofluorochromism, which involves a redox switch monitoring the luminescence properties, can be optically triggered.