Improved Performance by Modification of Cathode in Polymer Light-Emitting Diode Based on a Novel Se-Containing Electroluminescent Copolymer

The electroluminescent characteristics of polymer light-emitting diodes (PLEDs) with the structure ITO/PEDOT/ PFO-Selenophene copolymer/cathode were investigated. Various cathodes, such as Al, Li/Al, Ba/Al, LiF/Al and LiF/Ba/Al, were used for testing the device performances. The strongest light output (1112 cd/m²) and the highest quantum efficiency (0.74%) were achieved by using the LiF/Ba/Al cathode. A possible working mechanism for improving the PLED performance was discussed.