Rapid, Wet Chemical Fabrication of Radial Junction Electroluminescent Wires

A wet chemical process involving two electrodeposition steps followed by a solution casting step, the “EESC” process, is described for the fabrication of electroluminescent, radial junction wires. EESC is demonstrated by assembling three well-studied nanocrystalline (or amorphous) materials: Au, CdSe, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The tri-layered device architecture produced by EESC minimizes the influence of an electrically resistive CdSe emitter layer by using a highly conductive gold nanowire that serves as both a current collector and a negative electrode. Hole injection, at a high barrier CdSe–PEDOT:PSS interface (ϕh ≈ 1.1 V), is facilitated by a contact area that is 1.9–4.7-fold larger than the complimentary gold–CdSe electron-injecting contact (ϕe ≈ 0.6 V), contributing to low-voltage thresholds (1.4–1.7 V) for electroluminescence (EL) emission. Au@CdSe@PEDOT:PSS wire EL emitters are 25 μm in length, amongst the longest so far demonstrated to our knowledge, but the EESC process is scalable to nanowires of any length, limited only by the length of the central gold nanowire that serves as a template for the fabrication process. Radial carrier transport within these multishell wires conforms to the back-to-back diode model.