Light-emitting diodes composed of n-ZnO and p-Si nanowires constructed on plastic substrates by dielectrophoresis

In this study, light-emitting diodes (LEDs) composed of n-ZnO and p-Si nanowires (NWs) are constructed on flexible plastic substrates and their electroluminescence (EL) emission is characterized and analyzed in the flat and bent states. For each of the LEDs, ZnO NWs are aligned between the electrodes and crossed with a single Si NW by means of a dielectrophoresis (DEP). The number of aligned ZnO NWs determines the current levels and EL intensities of the LEDs. The EL spectra taken from the LEDs exhibit two types of emission, strong UV peaks at 385 nm and weak broad bands centered at 510 nm. The bending test of a single ZnO NW LED under a strain of 0.65% in the upwardly or downwardly bent states reveals that the turn-on voltage remains unchanged at 3 V and that the EL emission characteristics are stable. In addition, the performance of the LED is recovered when the device is returned to the flat state again after undergoing bending test.