Bulk Electroluminescence from Conjugated Polymer Thin Films via the Formation of Gold Nanoislands

Electroluminescence from extremely large planar-polymer light-emitting electrochemical cells (LECs) is demonstrated. By physical deposition of an ultrathin layer of gold on top of a polymer film, thousands of tiny light-emitting p–n junctions form upon the entire interelectrode spacing of 0.5 mm. This is attributed to the formation of gold nanoislands, which transform the emission profile from that of a single, narrow p–n junction to that of a more efficient bulk homojunction (see image), with 3.4-nm gold film deposited on top of the polymer film.