Abstract: A novel layer-ordered ultrathin film of poly(3,4-ethylene dioxythiophene)/arachidic acid (PEDOT:AA) was prepared by a modified Langmuir-Blodgett (LB) technique and an ordered conducting polymer embedded multilayer structure was constructed. The layer-ordered structure was deposited on an indium-tin oxide (ITO) surface as a hole injection layer for use as an organic light-emitting diode (OLED) and the luminance performance of the ITO/(PEDOT:PSS)/MEH-PPV(poly(2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene-vinylene))/Al device was investigated. Compared with electrostatic self-assembly (ESA) and spin-coating the poly(3,4-ethylene dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) film showed enhanced luminance efficiency. The higher luminance at an equivalent voltage and lower turn-on voltage was observed after the PEDOT:AA film was utilized as hole injection layer in OLED. The enhanced carrie injection efficiency was attributed to the good layer-ordered structure of PEDOT:AA film, which decreased the contact resistance between ITO and the emitting layer. Further investigation revealed that this layer-ordered conducting polymer film exhibited poor temperature stability because of weak hydrophilic and hydrophobic interactions between adjacent LB layers. These weak interactions result in the film structure changing from a layer-ordered structure into an unordered structure at higher temperatures.

Key words: Conducting polymer, Langmuir-Blodgett film, OLED, Hole injection layer, Self-assembly film