Ambipolar Charge Transport in Polymer Light-Emitting Diodes

Ambipolar charge-transport semiconducting polymer containing both a hole-transporting moiety, triphenylaniline (TPD), and an electron-transporting moiety, oxadiazole (OXD), in the main chain has been synthesized and investigated. OXD units allow an improvement in luminous efficiency (LE) of the polymer light-emitting diodes (PLEDs). One hundred times enhanced LE was observed from PLEDs made by the polymer with OXD units as compared with that PLEDs made by the polymer without OXD units. These results indicate that enhanced LE was attributed to an improvement in the charge balance of electrons and holes inside this ambipolar polymer.