DEVICE CHARACTERISTICS OF POLYMER LIGHT-EMITTING-DIODES

A model describing the device characteristics of polymer light-emittin g diodes (PLEDs) is presented. The recent observation that in poly(p-p henylene vinylene) (PPV) the hole current is space-charge-limited wher eas the electron current is strongly reduced by traps is taken into ac count. It is calculated that such an unbalanced electron and hole tran sport gives rise to a bias dependent efficiency. By comparison with ex periment it is found that the recombination process in PPV is mainly n on-radiative. Only 5% of the total number of recombinations contribute s to the light-output of the PLED.