Exclusive inkjet printed poly(3,4-ethylenedioxythiophene): Polystyrenesulfonate as anode in polymer light-emitting diodes

As general practice, Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS ) is the most widely used conducting polymer as electrode material in organic (polymer) devices. PEDOT: PSS film is fabricated by solution processes such as spin-coating, dip-coating, inkjet printing (IJP), contact printing, etc. One of the most complex operations in the fabrication process is forming conduction electrode lines or isolate devices from each other with the pattern of polymeric film IJP, which is a non-impact printing technology in which droplets of ink are jetted directly on a media to create a pattern. In this paper, PEDOT:PSS films, prepared by inkjet-printing and spin-coating methods, have been studied by using atomic force microscopy (AFM), micro-Raman spectroscopy and photoelectron spectroscopy measurements (PL). PEDOT:PSS films formed with the inkjet-printing method are appropriate for using as an anode for simplification of the fabrication process of polymer light-emitting diodes whose performance is about 1.2 cd/A. The performance is the same as spin-coating method. The performance was attributed to longer effective conjugation length of PEDOT chains in inkjet-printing PEDOT:PSS films, as suggested by their micro-Raman spectroscopy.