Tunable Emission Color of Iridium(III) Complexes with Phenylpyrazole Derivatives as the Main Ligands for Organic Light-Emitting Diodes

Abstract

Seven cyclometalated iridium(III) complexes Ir1−Ir7 based on phenylpyrazole derivatives as main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand were synthesized and fully characterized. The proligands of 1-), and 1-[4-(trifluoromethyl)phenyl]-1H-indazole (cf 3 -7-pidz, 2g)} were prepared with good yields. The emission maxima of all Ir(III) complexes can be tuned from 453 to 576 nm with different photoluminescence quantum yields (10.4−70.9%) by varying the type of substituent on the different main ligand frameworks. The organic light-emitting diodes using Ir(III) complexes as the emitters with blue, bluish-green, and yellow colors exhibit a maximum current efficiency and an external quantum efficiency of 39.2 cd A −1 and 14.8%, respectively.

Highly Luminescent Mono‐ and Dinuclear Cationic Iridium(III) Complexes Containing Phenanthroline‐Based Ancillary Ligand

“…Clearly, the absorption spectra of mononuclear complexes 1 and 2 are different (Figure a), while the spectra of the dinuclear complexes 3 , 4 and 5 are similar (Figure b). For the first series, compared to complex 1 , complex 2 displays a significant red‐shift in the lowest‐energy absorption region, resulting from the more extended π‐conjugation of the C ^ N ligands . For the second series, the trend of the absorption onset is 3 < 4 < 5 , similar to that observed for 1–2 .…”

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

“…It is evident that the high quantum yield of Ir1 correlates with the larger k r value and the smaller k nr value. Compared with phenylpyrazole‐based Ir(III) complexes published in our recent article, the k r rate constants of Ir1‐Ir2 are much larger, indicating that the complexes have more desirable photophysical properties.…”

“…Since the first‐ever yellow emitter [(bt) 2 Ir(acac)] was reported, only a few yellow‐emitting iridium (III) complexes have been developed, such as (fbi) 2 Ir(acac), (NEP) 2 Ir(acac), (MDPP) 2 Ir(acac), (3‐piq) 2 Ir(acac), (CzN‐Flpy) 2 Ir(acac), (TPAFlpy) 2 Ir(acac), (tpppyp) 2 Ir(acac), and so on. More recently, we reported a series of yellow‐emitting phenylpyrazole‐based iridium (III) complexes ( Ir2‐Ir4 ) . To obtain efficient OLEDs, we used fluorine groups to modify the main ligands in complexes Ir3 and Ir4 .…”

Cyclometalated iridium(III) complexes containing 2‐phenyl‐2H‐indazole ligand: Synthesis, photophysical studies, and DFT calculations

“…In Figure 2a, the intense bands below 350 nm are assigned to the spin‐allowed 1 π–π* transitions of the ligands. The weaker bands at about 400–450 nm can be ascribed to both metal‐to‐ligand (MLCT) and ligand‐to‐ligand (LLCT) transitions 12 . With the same ancillary ligand, the UV–vis absorption spectra of these complexes are perturbed by the substituent patterns on cyclometalated ligands.…”

“…Recently, we succeeded in the preparation of several yellow‐emitting iridium(III) complexes based on 2‐phenyl‐2 H ‐indazole (piz) ligands 12–14 . Through these research results, we can come to the following conclusions.…”