Molecularly “Engineered” Anode Adsorbates for Probing OLED Interfacial Structure−Charge Injection/Luminance Relationships:  Large, Structure-Dependent Effects

Molecule-scale structure effects at organic light-emitting diodes (OLED) anode−organic transport layer interfaces are probed via a self-assembly approach. A series of ITO anode-linked silyltriarylamine molecules differing in aryl group and linker density are synthesized for this purpose and used to probe the relationship between nanoscale interfacial chemical structure, charge injection and electroluminescence properties. Dramatic variations in hole injection magnitude and OLED performance can be correlated with the molecular structures and electrochemically derived heterogeneous electron-transfer rates of such triarylamine fragments, placed precisely at the anode−hole transport layer interface. Very bright and efficient (∼70 000 cd/m2 and ∼2.5% forward external quantum efficiency) OLEDs have thereby been fabricated.