Flexible and Metal-Free Light-Emitting Electrochemical Cells Based on Graphene and PEDOT-PSS as the Electrode Materials

We report flexible and metal-free light-emitting electrochemical cells (LECs) using exclusively solution-processed organic materials and illustrate interesting design opportunities offered by such conformable devices with transparent electrodes. Flexible LEC devices based on chemically derived graphene (CDG) as the cathode and poly(3,4-ethylenedioxythiophene) mixed with poly(styrenesulfonate) as the anode exhibit a low turn-on voltage for yellow light emission (V = 2.8 V) and a good efficiency 2.4 (4.0) cd/A at a brightness of 100 (50) cd/m(2). We also find that CDG is electrochemically inert over a wide potential range (+1.2 to -2.8 V vs ferrocene/ferrocenium) and exploit this property to demonstrate planar LEC devices with CDG as both the anode and the cathode.