Improving the lifetime of a polymer light-emitting diode by introducing solution processed tungsten-oxide

We report a polymer light-emitting diode (PLED) using solution processed tungsten-oxides (WOx). Coating of a thin WOx layer on PEDOT:PSS increases the current efficiency of PLED from 9.11 to 9.90 cd A(-1) because of the improved conductivity of the PEDOT: PSS due to the incorporation of WOx. Improvement of the conductivity of PEDOT: PSS promotes hole injection into the emission layer. The lifetime of a PLED with WOx layers on both sides of PEDOT: PSS is 1.8 x 10(6) h which is around 20 times longer than that of the control device at 1000 cd m(-2). The enhanced lifetime is due to the suppression of the indium diffusion from ITO to PEDOT: PSS by WOx and also due to the prevention of acidic damage that can occur to ITO and the organic emission layer by sulfate ions in PEDOT:PSS.