In this study, the effect of ultraviolet treatment on the band bending at the poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)/indium tin oxide (PEDOT: PSS/ITO) interfaces were researched. The authors suggested that ultraviolet treatment could lead to a reduction in the band bending at the PEDOT: PSS/ITO interface, owing to the removal of carbon contamination at the ITO surfaces and a decrease in the number of the trap-states at the PEDOT: PSS/ITO interface. (C) 2010 Elsevier B. V. All rights reserved.