Electrochemical Deposition of Perylene-Based Thin Films from Aqueous Solution and Studies of Visible-Light-Driven Oxidation of Alcohols

Perylene-based organic semiconductors are attractive photoactive materials due to their broad visible-light absorption, large extinction coefficients, high photostability, and relatively low cost. However, the fabrication of perylene-based organic thin films often suffers from complicated and tedious procedures. Herein, we show a simple and versatile electrochemical deposition method for the fabrication of thickness-controllable poly(perylenecarboxylate) thin films (named PPCA) from a potassium salt of 3,4,9,10-perylenetetracarboxylate (K4PTC) aqueous solution. Detailed spectroscopy studies reveal that the partially oxidative decarboxylation of PTC4- is responsible for the formation of PPCA thin films, and a plausible growth mechanism was proposed. Interestingly, the H-aggregate PPCA thin films show excellent photoelectric properties and enable visible-light-driven oxidation of benzyl alcohol to benzaldehyde by using a stable radical, TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy), as a redox mediator. The simplicity of the electrochemical deposition method together with the excellent photofunctionality of perylene-based semiconductors showed herein leads to a great promise to design highly photoactive thin films for applications in photovoltaic, water-splitting, and light-driven organic synthesis.