Efficiency enhancement of an organic light-emitting diode with a cathode forming two-dimensional periodic hole array

We fabricated an organic light-emitting diode using a pi-conjugated polymer emissive layer sandwiched between two semitransparent electrodes: an optically thin gold film anode, whereas the cathode was in the form of an optically thick aluminum (Al) film with patterned periodic subwavelength two-dimensional hole array that showed anomalous transmission in the spectral range of the polymer photoluminescence band. At similar current densities, we obtained a sevenfold electroluminescence efficiency enhancement with the patterned Al device compared with a control device based on unperforated Al electrode. (C) 2005 American Institute of Physics.