Synthesis and luminescent properties of two cross-linkable Ir(III) complexes

Two cross-linkable iridium(III) complexes, Ir(L)2(acac) and Ir(L)2(Stpip), where L = 1-phenyl-2-(4′-vinyl-[1,1′-biphenyl]-4-yl)-1H-benzo[d]imidazole, acac = acetylacetonate, Stpip = bis(diphenylphorothioyl)amide, were synthesized and characterized by elemental analysis, NMR (1H and 13C) and HRMS spectra. The iridium(III) complexes exhibited excellent thermal stability and green-yellow emission with a maximum main peak at 563 nm. The photoluminescence quantum yields of Ir(L)2(acac) and Ir(L)2(Stpip) were 2.77% and 1.80%, respectively, in CH2Cl2 solution. The vacuum-processed electroluminescence device fabricated from Ir(L)2(acac) at 4 wt% doping concentration exhibited a maximum current efficiency (CEmax) of 26.3 cd/A, a maximum brightness of 9645 cd/m2 and a maximum external quantum efficiency (EQEmax) of 14.7%, respectively. The solution-processed electroluminescence device based on Ir(L)2(acac) exhibited a maximum current efficiency (CEmax) of 3.71 cd/A, a maximum brightness of 2237 cd/m2 and a maximum external quantum efficiency (EQEmax) of 1.36%, respectively.