Photophysical properties and OLEDs performances of blue Pt(II) and broad-band fac/mer Ir(III) cyclometallated complexes carrying 1-azatriphenylene ligand

Luminescent cyclometalated Iridium(III) complexes have been shown to be excellent candidates in organic light emitting diodes (OLEDs) because of their superior photophysical properties. For general lighting applications of OLEDs, broad band luminescent materials would be beneficial, to simplify device architectures, since white light can be produced using only two emitters: one blue and one broadband (yellow-red). The photophysical properties of fac/mer Ir((C^N)3 and Pt(C^N)(dpm) [where C^N is the rigid 1-azatriphenylene or dibenzo[f,h]quinoline, DBQ)] will be described. Mer-Ir(DBQ)3 shows broad featureless emission in solution between 500-750 nm (max,em= 586nm, QE= 0.5), whereas fac-Ir(DBQ)3 has narrow featureless emission between 475-700nm (max,em= 535nm, QE= 0.5). The rigid structure of DBQ prevents mer to fac isomerization processes that occur in other mer-Ir((C^N)3 complexes. Fac and mer Ir(DBQ)3 have similar emission profiles as fac and mer Ir(ppy)3 (ppy = 2-phenylpyridine). These results are interesting considering that DBQ has a larger -system than ppy. Theoretical calculations has been carried out to elucidate the experimental results. OLED devices, displaying broad emissions and 12% external quantum efficiency, have been prepared using fac/mer Ir(DBQ)3 mixtures.