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transition from a laboratory scale to an industrial level and an therefore, achieving good device performance depends on several issues, such as electrode characteristics, polymer/electrode inter-duced to control charge injection and charge balance, such as et al. [5] found that ITO acts as a source of oxygen which leads to oxidation causing device aging; therefore, the insertion of the hole-injection-transporting layer is necessary to avoid the direct contact between the emissive LEP layer and ITO as well as to Thin Solid Films 515 (2007facial effect, and LEPmorphological and optoelectronic properties.understanding of the effect of processing on device performance is now paramount. The device performance is mainly concerned with four factors, namely, (i) device efficiency and brightness, (ii) power consumption, (iii) device lifetime, and (iv) colour control [1]. The structure of the PLEDs shown in Fig. 1 consists of several elements, i.e. an emissive component (light emitting polymer, LEP), a hole transporting layer (poly(3,4-ethylenediox