Sublimable Cationic Iridium(III) Complexes with 1,10-Phenanthroline Derivatives as Ancillary Ligands for Highly Efficient and Polychromic Electroluminescence.

A novel series of four sublimable cationic iridium(III) complexes have been prepared with 1,10-phenanthroline derivatives as ancillary ligands and the same negative counter-ion, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, which has a large steric hindrance and widely dispersed charges, thereby increasing the ionic radii, reducing the electrostatic interaction, and thus improving the volatility. Their structural, photophysical, electrochemical, and thermal properties have been fully characterized. Upon excitation, these compounds show polychromic emission varying from green to orange in solution, which are blue-shifted in the solid state to different extents due to π-π conjugate effects in the ancillary ligands and the resulting molecular aggregation. OLEDs fabricated by vacuum evaporation deposition demonstrated desirable device performance with high efficiency and brightness, exhibiting various electroluminescent colors dependent upon doping concentration.