Solution-Processed Flexible ITO-Free Organic Light-Emitting Diodes Using Patterned Polymeric Anodes

We discuss a thin-film spin-coating and patterning process of a conductive polymer electrode for flexible organic light-emitting diodes (OLEDs). For the polymeric anode, dimethylsulfoxide (DMSO)-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been spin coated on a non-ionic surfactant layer that was pre-coated on the polyethersulfone (PES) substrate. A peel-off method has then been employed to pattern the conductive polymer anode without UV irradiation or heat treatment involved. A peel-off pattern is induced by different adhesion energy among a hydrophobic flexible substrate, a hydrophilic polymeric anode layer, and an adhesive film peeler that is in contact with the polymer anode. With this process technology, we have successfully fabricated solution-processed flexible green OLEDs, showing a peak luminescence of 6000 and a maximum current efficiency of 16.2 cd/A.