Synthesis and luminescence 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, and Stpip = bis(diphenylphorothioyl)amide, were synthesized and characterized by elemental analysis, NMR (H-1 and C-13) spectroscopy and HRMS. 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(-1), a maximum brightness of 9645 cd m(-2) and a maximum external quantum efficiency (EQE(max)) of 14.7%. The solution-processed electroluminescence device based on Ir(L)(2)(acac) exhibited a maximum current efficiency (CEmax) of 3.71 cd A(-1), a maximum brightness of 2237 cd m(-2) and a maximum external quantum efficiency (EQE(max)) of 1.36%.