Increase in indium diffusion by tetrafluoromethane plasma treatment and its effects on the device performance of polymer light-emitting diodes

Abstract

The effects of tetrafluoromethane (CF4) plasma treatment of indium-tin-oxide (ITO) anode on indium diffusion into a poly(3,4-ethylene dioxythiophene):poly(styrene sulphonate) (PEDOT:PSS) layer were studied. Auger electron spectroscopy (AES) depth profile showed that 0.2 at. % indium was present in the PEDOT:PSS layer when ITO was not plasma treated. The plasma treatment of ITO increased the indium concentration to ∼6 at. %. The increase in indium can be explained by an oxygen deficiency in the CF 4 plasma treated ITO. The presence of indium in the PEDOT:PSS layer showed a correlation with performance degradation of polymer light-emitting diodes. © 2008 American Institute of Physics.