Vertical nanowire light-emitting diode

Abstract

We report room-temperature, white-color electroluminescence in vertically oriented ZnO nanowires. Excitonic luminescence around 380 nm is observed as a shoulder on a broader defect-related band covering all of the visible range and centered at 620 nm. The ZnO nanowires are grown in a low-temperature process on $\mathrm{Sn}{\mathrm{O}}_2$ -coated glass substrates, employing a technique that is suitable for large-area applications. The nanowires are robustly encapsulated in a thin polystyrene film deposited from high-molecular-weight solutions. Electron injection occurs through the transparent $\mathrm{Sn}{\mathrm{O}}_2$ layer, while hole injection is mediated by a $p$ -doped polymer and an evaporated Au contact. Stable device operation is observed at ambient conditions on the time scale of 1 h.