버퍼층과 음전극에 따른 유기 발광 소자의 전기적 특성과 발광 효율

Abstract

We have studied electrical properties and luminous efficiency of organic light-emitting diodes(OLEDs) with different buffer layer and cathodes in a temperature range of 10 K and 300 K. Four different device structures were made. The OLEDs are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinato) aluminum(Ⅲ) (Alq3) as an electron transport and emissive layer, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a buffer layer. And LiAl was used as a cathode. Among the devices, the ITO/PEDOT:PSS/TPD/Alq3/LiAl structure has a low energy-barrier height for charge injection and show a good luminous efficiency. We have got a highly efficient and low-voltage operating device using the conductive PEDOT:PSS and low work-function LiAl. From current-voltage characteristics with temperature variation, conduction mechanisms are explained SCLC (space charge limited current) and tunneling one. We have also studied energy barrier height and luminous efficiency at various temperature.