Electroluminescence from ZnO nanowire/polymer composite p-n junction

The characteristics of a hybrid $p\text{-}n$ junction consisting of the hole-conducting polymer poly(3,4-ethylene-dioxythiophene)-poly(styrene-sulfonate) (PEDOT/PSS) and $n\text{-}\mathrm{Zn}\mathrm{O}$ nanorods grown on an $n\text{-}\mathrm{Ga}\mathrm{N}$ layer on sapphire are reported. Spin coating of polystyrene was used to electrically isolate neighboring nanorods and a top layer of transparent conducting indium tin oxide (ITO) was used to contact the PEDOT/PSS. Multiple peaks are observed in the electroluminescence spectrum from the structure under forward bias, including ZnO band edge emission at $\sim 383\mathrm{nm}$ as well as peaks at 430, 640, and $748\mathrm{nm}$ . The threshold bias for UV light emission was $<3\mathrm{V}$ , corresponding to a current density of $6.08\mathrm{A}{\mathrm{cm}}^{-2}$ through the PEDOT/PSS at $3\mathrm{V}$ .