Electric-field-induced optical second-harmonic generation in poly(phenylene vinylene) light-emitting diodes (original) (raw)

We demonstrate second-harmonic generation in polymeric light-emittingdiodes built in a layer structure of indium tin oxide, poly(phenylene vinylene) and aluminum. The second-harmonic intensity generated in the active zone of the diode depends quadratically on the applied reverse bias. In order to account for the bias dependence of the measured intensity a simple model is given in that the signal consists of two contributions: a constant, bias independent contribution from the indium tin oxide / poly(phenylene vinylene) interface and a second one that depends on the e ective bias at the organic metal-semiconductor contact. Further applications for second-harmonic spectroscopy in organic semiconductors are discussed.