Polymer diodes made using a bilayer of doped poly(3,4-ethylenedioxythiophene) and a semiconducting polymer in a sandwich structure with two low-work-function metals are reported. The conducting polymer layer acted as a modifier of the injection properties of the low-work-function metal, allowing easy hole injection. Upon insertion of the conducting polymer layer, the contact-limited current flow became bulk limited. With this anode, the fabrication of diodes with a rectification ratio of seven orders of magnitude was possible. We present patterned microdiodes made with crossing of 10 μm lines, showing similar performance as the mm-size diode. © 1999 American Institute of Physics.