A kind of novel structure polymer, a poly(phenylenevinylene) (PPV) derivative containing electron-transporting groups on the main chain (OPPV), was developed according to the polycondensation mechanism. The I-V characteristics at the low-voltage region with negative differential resistance were observed in the same model of organic light-emitting diodes with the OPPV polymer. The different external parameters, including the device structure, layer thickness, morphology, and homogeneity of indium tin oxide and the polymer, were also investigated. The performance improvement in the organic negative differential resistance and a possible mechanism are discussed. (C) 2001 John Wiley & Sons, Inc.