Fine growth control of electrografted homogeneous thin films on patterned gold electrodes

Frédéric Lebon (1) , R. Cornut (1) , V. Derycke (1) , B. Jousselme (1)

1 LICSEN UMR 3685 - Laboratoire Innovation en Chimie des Surfaces et NanoSciences

Electrochemical grafting of two different diazonium salts was performed on patterned gold electrodes of micrometric size. One of the molecules, a tris-bipyridine iron (II) derivative (TBPFe) enables a fine control over the final thickness of the electrografted layer thanks to its redox centers that acts as intermediate for charge transfers between the solution and the working electrode. The other one, an aromatic cycle with a fluorinated carbon chain (DzF8), forms an insulating layer that stops the charge transfer from the working electrode to the solution and thus limits the thickness of the resulting organic layer. Grafting parameters (concentration, time, tip passivation, etc.) were investigated in details. Their precise control leads to compact and homogeneous thin films. Smooth TBPFe layers with an adjustable thickness in the 5–100 nm range are obtained, while the thickness is limited to 2–6 nm in the DzF8 case. With the achieved film quality, direct metal evaporation on top of these electrodes is possible and yields 85% of working devices. Electrical measurements for the two molecules are compared for different thicknesses.

Domaines: Matériaux

Frédéric Lebon, R. Cornut, V. Derycke, B. Jousselme. Fine growth control of electrografted homogeneous thin films on patterned gold electrodes. Electrochimica Acta, 2019, 318, pp.754-761. ⟨10.1016/j.electacta.2019.06.115⟩. ⟨cea-02295172⟩