ENHANCED PERFORMANCE OF POLYMER LIGHT-EMITTING-DIODES USING HIGH-SURFACE-AREA POLYANILINE NETWORK ELECTRODES

Light-emitting diodes (LEDs) of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4- phenylene vinylene) were fabricated using high surface area hole-injecting network electrodes made in situ from blends of polyaniline (PANI) in low molecular weight polyester resin. Due to the high interface area between the PANI network and the active luminescent layer and enhancement of the local electric field at the rough surface of the PANI network, charge carrier injection was significantly improved. LEDs using the PANI network electrode have lower device operating voltage, higher quantum efficiency, and significantly increased brightness. Polymer LEDs fabricated with the PANI-CSA network as anode and aluminum:lithium alloy (0.2% Li) as the cathode turn on at 1.7 V, and achieve a brightness in excess of 400 cd/m2 at 3 V with a measured external quantum efficiency of 2.23% photons/electron. © 1995 American Institute of Physics.