새로운 Phenothiazine 공중합체의 합성과 발광 특성에 관한 연구

Abstract

Since the first report of the PLED(Polymer Light Emitting Diode) by Friend group, a lot of research has been done for improving the device efficiency and for tuning the emission color. PLED is difficult to be fabricated to multi-layer, unlike SMOLED(Small molecular Organic Light Emitting Diodes). So, it is necessary to develop new polymers with electron and hole injection/transporting properties. One of the strategies to improve efficiency of PLED is to synthesis new efficient polymers with a hole or electron transporting materials. It has been continuously reported that the π-conjugated polymers containing 1,3,4-oxadiazole (OXD) or 1,2,4-triazole (TAZ) in the main chain or side chain to improve electron transporting properties. Another strategy is to introduce Ca or Mg, since they have a higher work function than Al, as a cathode. Among various materials reported as emitting materials, this paper used phenothiazine derivatives. It is not a well known material, as an emitting material. The phenothiazine ring is very strong electron donor, since it has sulfur atom. In addition, phenothiazine based polymer reduces π-stacking, since phenothiazine has a highly nonplanar geometry. In this paper, we report a different synthesis, optical, electrochemical, and electroluminescence properties of novel phenothiazine based polymer containing OXD pendants or TAZ pendants in the main chain or side chain to improve electron injection/transporting properties and phenothiazine based polymer without OXD pendants or TAZ pendants. And we also report the necessity of PEDOT:PSS layer when phenothiazine is used as an emitting material.