Highly efficient solution-processed pure red phosphorescent organic light-emitting diodes using iridium complexes based on 2,3-diphenylquinoxaline ligand

Highly efficient yellow‐emitting iridium(III) complexes based on fluorinated 2‐(biphenyl‐4‐yl)‐2H‐indazole ligands: Syntheses, structures, properties, and density functional theory calculations

“…The average Ir–P bond lengths for Ir1 (2.493 Å) are close to those found in Ir2 (2.513 Å). The average Ir–C bond lengths (2.064 Å for Ir1 , 2.051 Å for Ir2 ) and Ir–N bond lengths (2.045 Å for Ir1 , 2.034 Å for Ir2 ) are in agreement with those of previously reported complexes . Obviously, the Ir–Pav distances are longer than the Ir–Cav and Ir–Nav distances in both complexes.…”

Structural and Photoluminescent Properties of Near‐Infrared Emissive Bis(2,3‐Diphenylbenzoquinoxalinato)(2‐Pyrazinecarboxylato)ridium(III)

“…However, near‐infrared (NIR) emissive iridium(III) complexes are rare, even though NIR‐emitting materials are expected to be applied for night‐vision displays and sensors for the needs in both military and civilian uses . Recently, we reported pure red emissive iridium(III) complex bearing 2,3‐diphenylquinoxalinato (dpq) and 2‐pyrazinecarboxylate (prz) ligands, (dpq) 2 Ir(prz), which adopted an octahedral symmetry around iridium cation . The red emission was originated from the intra‐ligand charge transfer ( 3 ILCT) in a π‐conjugated dpq moiety.…”

“…Film PL spectrum showed a blue‐shifted emission by 8 nm when compared to the solution spectrum, which is due to the motional relaxation of excited‐state geometry resulting from the rigidity of the matrix in film . Recently, pure red‐emissive iridium(III) complex, (dpq) 2 Ir(prz), was reported and the red emission was attributed to the π‐extended cyclometalated dpq ligand . The iridium complexes with largely conjugated ligands have shown efficient red emission due to allowed intersystem crossing .…”

Crystal structure of 2,3-bis(4-methylphenyl)benzo[g]quinoxaline

“…They act as chelating agents bearing ring complexes bounded by a benzene ring and a pyrazine ring. We have reported, for example, deep-red emissive iridium(III) complexes containing 2,3-diphenylquinoxaline (dpqH), in which red emissions contributed to the conjugated structure of the dpq ligand (Song et al, 2015). The use of long conjugated compounds as metal coordination ligands could be an approach to develop novel emitters toward red-shift emission up to near-infrared (NIR) wavelengths due to intersystem crossing (Ahn et al, 2009).…”