Screen-Printed Poly(3,4-Ethylenedioxythiophene):Poly(Styrenesulfonate) Grids as ITO-Free Anodes for Flexible Organic Light-Emitting Diodes

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) grids have been successfully constructed by roll-to-roll compatible screen-printing techniques and have been used as indium tin oxide (ITO)-free anodes for flexible organic light-emitting diodes (OLEDs). The grid-type transparent conductive electrodes (TCEs) can adopt thicker PEDOT: PSS grid lines to ensure the conductivity, while the mesh-like grid structure can play an important role to maintain high optical transparency. By adjusting grid periods, grid thickness and treatment of organic additives, PEDOT: PSS TCEs with high optical transparency, low sheet resistance, and excellent mechanical flexibility have been achieved. Using the screen-printed PEDOT: PSS grids as the anodes, ITO-free OLEDs achieved peak current efficiency of 3.40 cd A⁻¹ at the current density of 10 mA cm⁻², which are 1.56 times better than the devices with ITO glass as the anodes. The improved efficiency is attributed to the light extraction effect and improved transparency by the grid structure. The superior optoelectronic performances of OLEDs based on flexible screen-printed PEDOT: PSS grid anodes suggest their great prospects as ITO-free anodes for flexible and wearable electronic applications.