We have developed highly durable polymer/organic heterostructure doped light-emitting diodes using a novel poly-TPD(PTPD) as hole transport material and a highly fluorescent rubrene as dopant.The basic structure of the heterostructure is PTPD/Alq_3.With the doping of both layers,the electroluminescence(EL) quantum efficiencies at 1.47% are about 2 times greater than that of the undoped devices at 0.74%.Compared with undoped devices and conventional TPD/Alq_3 diodes,the stability of the doping devices has significant improvements.We discuss the mechanisms of the enhanced stability.