Two Green‐Phosphorescent Iridium Complexes with 2‐Phenylpyrimidine Derivatives and Tetraphenylimidodiphosphinate for Efficient Organic Light‐Emitting Diodes

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Two phosphorescent IrIII complexes Ir1 and Ir2 containing 5‐fluoro‐2‐[4‐(trifluoromethyl)phenyl]pyrimidine and 2‐(3,4‐difluorophenyl)‐5‐fluoropyrimidine as cyclometalated main ligand and tetraphenylimidodiphosphinate as ancillary ligand were synthesized. Ir1 was characterized by single‐crystal X‐ray crystallography. Ir1 and Ir2 show green emissions peaking at 527 and 513 nm, respectively. By using the two complexes as emitters, organic light‐emitting diodes (OLEDs) with the structure of TAPC (1,1‐bis[4‐(di‐p‐tolylamino)phenyl]cyclohexane, 40 nm)/Ir1 or Ir2 (10 wt.‐%):mCP (1,3‐bis(9H‐carbazol‐9‐yl)benzene, 20 nm)/TmPyPB (1,3,5‐tris(m‐pyrid‐3‐ylphenyl)benzene, 30 nm)/LiF (1 nm)/Al (100 nm) showed high performance with maximum current efficiencies as high as 81.91 or 71.17 cd A–1 and maximum external quantum efficiencies of 20.8 or 21.3 %, respectively. The low‐efficiency roll‐off ratios of the two devices suggest that the two complexes have potential applications in OLEDs.