Blue-emitting heteroleptic Ir(<scp>iii</scp>) phosphors with functional 2,3′-bipyridine or 2-(pyrimidin-5-yl)pyridine cyclometalates

Abstract

We have synthesized four Ir(iii) metal complexes () bearing dual fluorine-free cyclometalates that are derived from 2',6'-dimethoxy-4-t-butyl-2,3'-bipyridine (pypy)H or 2-(2,4-dimethoxypyrimidin-5-yl)-4-t-butylpyridine (pmpy)H and a third ancillary, e.g. 5-pyridin-2-yl-pyrazolate (Pz) or 5-pyridin-2-yl-pyrrolide (Pr), respectively. The Ir(iii) complexes and were examined by X-ray diffraction studies for providing the structural proofs. Photophysical properties were next measured in CH2Cl2 at RT, among which the pypy complexes and showed an identical structured emission with an E0-0 peak located at 458 nm, while the corresponding pmpy derivative displayed the most blue-shifted E0-0 peak at 444 nm. Organic light-emitting diodes (OLEDs) were fabricated using multiple layered architecture and the aforementioned phosphor at 8 wt% doping level. The associated OLED performances, cf. max. E.Q.E. = 9.0%, 14.3%, 5.8% and 9.4% and CIEx,y coordinates at (0.16, 0.22), (0.16, 0.24), (0.16, 0.17) and (0.16, 0.20) at 100 cd m(-2) for phosphors in sequence, confirmed their potential to act as blue dopants for phosphorescent OLEDs.