Increase in intensity of electrochemiluminescence from cell consisting of TiO2 nanohole array film

The increase in the intensity of electrochemiluminescnece (ECL) from cells consisting of titania nanohole array film (T-NHA-AL) is reported. The T-NHA-AL with a thin alumina insulation layer on the edge was prepared by an improved liquid- phase deposition method. The T-NHA-AL was sandwiched between two transparent conductive glasses (F-doped SnO2, FTO). The space between these two FTO substrates was filled with a solution of Ru(bpy)(3)(PF6)(2) in propylene carbonate. The ECL from the cell was observed by applying ac bias on the FTO glass electrode. The ECL from the cell consisting of the T-NHA-AL was larger than that without T-NHA-AL (the cell with flat FTO glasses). In addition, the ECL intensity from the cell consisting of T-NHA-AL was higher than that consisting of alumina nanohole array (anodically oxidized porous alumina). The increase in the intensity of the ECL from the cell consisting of T-NHA-AL was explained by the electron injection from the large surface of the T-NHA-AL and the confinement of the luminescence species [Ru(I) and Ru(III)] in the restricted area of nanopores in the T-NHA-AL film. If a TiO2 nanohole array film without the thin Al2O3 layer on the edge (T-NHA) was inserted between these two electrodes, short circuiting occurred through the T-NHA film. It is emphasized that the thin alumina insulation layer at the edge of the T-NHA-AL film is essential to realize an increase in ECL intensity. (c) 2008 The Electrochemical Society.