Electroluminescence from printed stellate polyhedral oligomeric silsesquioxanes

Iridium-based stellate (star-shaped) polyhedral oligomeric silsesquioxane macromolecular dyes were synthesized and an inkjet printing process to deposit inks based on these materials was developed. Polymeric-macromolecular blended light emitting diodes based on these hybrid organic-inorganic dyes were studied. We find peak luminances of similar to 10,000 cd/m(2) with peak quantum efficiencies of similar to 2.5% are possible with the printed layers. White light interferometry measurements suggest that large printed layer thicknesses and interface roughness play a crucial role in limiting device performance. A cumulative coffee-ring effect is considered to be the source of interface roughness.