Self-assembled monolayers of protonated poly(amidoamine) dendrimers on indium tin oxide

Abstract

We have investigated the change of work function of indium tin oxide (ITO) anodes induced by adsorption of positively charged poly(amidoamine) (PAMAM) dendrimers. Kelvin probe characterization of the functionalized ITO films and electroabsorption measurements on polymer light-emitting diodes incorporating poly(9,9-dioctylfluorene) active layers revealed an abrupt (0.55 eV) lowering of the effective work function upon addition of the adsorbed layer and a weak dependence on the PAMAM generation. We interpret our results with an electrostatic model accounting for both positively charged amines and for possible contaminations providing compensating negative charges. © 2008 American Institute of Physics.