Electrogenerated chemiluminescence in polyelectrolyte multilayers: efficiency and mechanism

The presence of an ultrathin film of polyelectrolyte complex, formed by the multilayering method, on an electrode was shown to enhance the intensity of electrogenerated chemiluminescence (ECL) from the tris(2,2')bipyridylruthenium(II)/tripropylamine system. Platinum electrodes coated with up to 17 layers of poly(diallyldimethylammonium chloride) or poly(vinylmethylpyridine), alternately layered with poly(styrenesulfonate), revealed significant differences in enhancement of ECL, depending on the identity of the multilayer. ECL following deposition of each layer showed an oscillating intensity of light emission, which alludes to the importance of surface and bulk charge. This effect, along with others, such as increased output with increasing tripropylamine concentration, was used to suggest a mechanism for enhanced ECL intensity at multilayer-coated electrodes.