100% phosphorescence quantum efficiency of Ir ( III ) complexes in organic semiconductor films

We demonstrate that three Ir ( III ) complexes used as principal dopants in organic electrophosphorescent diodes have very high photoluminescence quantum efficiency ( η PL ) in a solid-state film. The green emitting complex, fac-tris(2-phenylpyridinato)iridium(III) [ Ir ( ppy ) 3 ] , the red-emitting bis [ 2 - ( 2 ′ - benzothienyl ) pyridinato - N , C 3 ′ ] (acetylacetonato)iridium(III) [ Btp 2 Ir ( acac ) ] , and the blue complex bis [ ( 4 , 6 - difluorophenyl ) pyridinato - N , C 2 ] ( picolinato ) iridium ( III ) ( FIrpic ) were prepared as codeposited films of varying concentration with 4 , 4 ′ - bis ( N - carbazolyl ) - 2 , 2 ′ - biphenyl , a commonly used host material. The maximum η PL values for Ir ( ppy ) 3 , Btp 2 Ir ( acac ) , and FIrpic were, respectively, 97 % ± 2 % (at 1.5 mol % ), 51 % ± 1 % (at 1.4 mol % ), and 78 % ± 1 % (at 15 mol % ). Furthermore, we also observed that the maximum η PL of FIrpic reached 99 % ± 1 % when doped into the high triplet energy host, m - bis ( N - carbazolyl ) benzene , at an optimal concentration of 1.2 mol % .