Bipolar Electrode Based Reversible Fluorescence Switch Using Prussian Blue/Au Nanoclusters Nanocomposite Film.

A highly efficient fluorescence switch system based on a closed bipolar electrode (C-BPE) system was proposed for the first time. Here, Au nanoclusters (Au NCs) were premodified on one pole of the BPE and acted as the fluorescent donor. On the basis of the spectral overlap between the absorbance of electrochromic material-Prussian blue (PB) and the fluorescence spectrum of Au NCs, fluorescence quenching ("off" state) induced by the inner filter effect was observed. Due to the electrochemical reversible redox reaction between PB and Prussian white, switching the polarity of driving voltage could easily achieve the fluorescence recovery of the Au NCs, corresponding to the "on" state. Through the reasonable design of C-BPE and optimization of driving voltage, the on-off ratio of the integrated fluorescence switch was up to 2.7 and a good fatigue resistance while performing 10 on-off cycles was obtained owing to the good stability of Au NCs and the reversible redox feature of PB. The introduction of BPE made the fluorescence switch more simple and controllable compared with the traditional three-electrode system, which will provide a new route for the design of the electrical-stimuli responsive fluorescence switch, especially for the integration of the miniaturized device.