Fabrication and characterization of OLEDs using PEDOT:PSS and MWCNT nanocomposites

Nanocomposites of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and multi-wall carbon nanotubes (MWCNTs) were investigated as hole injection layers in organic light-emitting diodes (OLEDs) consisting of a hole transport layer of N,N'-diphenyl-N,N'-di(m-tdyl)benzidine (TPD) and a light-emitting/electron transport layer of tris(8-hydroxyquinolinato)aluminium (Alq3) sandwiched between a transparent ITO anode based on polyethylene terephthalate (PET) substrate and a metal cathode. The OLEDs were fabricated by physical vapor deposition method and the current-voltage-luminescence (I-V-L) characteristics of the devices were examined. It was found that high light intensity can be obtained by adopting nanocomposites of PEDOT:PSS and MWCNTs as hole injection layer of OLEDs. Reasons for the improved performance of the devices were discussed. The improved electric properties of the nanocomposites might be the reason for the improvement of OLED performance achieved by incorporating MWCNTs into hole injection layer of PEDPT:PSS.