Highly efficient near-infrared organic excimer electrophosphorescent diodes

The authors report the fabrication of very high efficiency near-infrared (NIR) organic light-emitting diodes (LEDs) based on a series of terdentate cyclometallated phosphorescent Pt(II) complexes PtLCl as the emitting layer. The LEDs exhibit exclusive NIR excimeric phosphorescence peaking between 705 and 720nm for three different organic ligands (L). Due to the high excimer emission quantum yields of these Pt complexes and to confinement of the recombination zone within the emission layer, unusually high external quantum efficiencies from 9.8% to 10.7% photons/electron and a high forward light output exceeding 15mW∕cm2 were achieved.