Synthesis, Structure, and OLEDs Application of Cyclometalated Iridium(III) Complexes Utilizing Substituted 2‐Phenylpyridine

Abstract

The syntheses, structures, photophysical, and electroluminescent properties of three green emitting heteroleptic cyclometalated iridium(III) complexes, (ptfmppy) 2Ir(pic) (Ir1), (dfptfmppy) 2Ir(pic) (Ir2), and (tfptfmppy) 2Ir(pic) (Ir3) [ptfmppy = 5‐(trifluoromethyl)‐2‐(phenyl)pyridine, dfptfmppy = 5‐(trifluoromethyl)‐2‐(2,4‐difluorophenyl) pyridine, tfptfmppy = 5‐(trifluoromethyl)‐2‐(2,3,4‐difluorophenyl)pyridine, and picH = picolinic acid] and the results of an investigation on their suitabilities for phosphorescent organic light‐emitting diodes (phOLEDs) applications are reported. X‐ray single crystal structures showed that iridium(III) cations in Ir1 and Ir2 adopted six‐coordinated geometries involving two C and two N atoms from substituted‐ppy, and one N and one O atom from pic, which produced a distorted octahedral geometry. Photoluminescence (PL) spectra revealed that the synthesized iridium(III) complexes exhibited emissions at 497 ~ 534 nm in dichloromethane with high photoluminescence quantum yield (PLQY) ranging from 60 to 67%, and TGA experiments showed that they had good thermal stabilities. In Ir3, the conjugation effect rather than the electronic effect of the 3‐positioned fluorine atom on phenyl ring of ppy increased the HOMO energy level causing bathochromic shifts. Electroluminescent devices of ITO(110 nm)/PEDOT:PSS (40 nm)/PVK:TCTA:OXD‐7:Ir (80 nm)/TmPyPB (20 nm)/Al (100 nm) were fabricated using the iridium(III) complexes as phosphors in an emitting layer, and their electroluminescent performances were investigated.

Polyfluorene-based white light conjugated polymers incorporating orange iridium(iii) complexes: the effect of steric configuration on their photophysical and electroluminescent properties

“…It could be attributed to the auxiliary ligand of 1,2,4-triazole derivatives 27 combined with the conjugated PF that decreased the HOMO energy level and increased the energy gap between the HOMO and LUMO energy level of the incorporated iridium( iii ) complexes in the polymers. 28,29 In the hyperbranched polymers, though the main and auxiliary ligands were both combined with PF, the main ligands were dominant to the emission of iridium( iii ) complexes. The fluorescence quantum yields (QYs) and the lifetime ( τ ) of orange emission from conjugated polymer films were recorded in Table 2 .…”

Exploiting the Reactivity of Fluorinated 2-Arylpyridines in Pd-Catalyzed C–H Bond Arylation for the Preparation of Bright Emitting Iridium(III) Complexes

“…Herein, we report the synthesis, the X-ray crystal structures, and the solution-state photophysical properties of ( i ) a family of 2-picolinato complexes of the form [Ir­(Ar-dF-CF 3 ppy) 2 (pic)] F and ( ii ) a series of positively charged complexes [Ir­(Ar-dF-CF 3 ppy) 2 (dmbpy)]­PF 6 G having a 4,4′-dimethyl-2,2′-bipyridine. This will allow us to evaluate the role of the added aryl substituent at the cyclometalated difluorinated phenyl ring of the C^N ligand on the photophysical properties by comparison with the unsubstituted analogues ( F1 /F5 and G1/G5 , Schemes and ) used as reference complexes . We also show that the color of the emission can be fine-tuned by changing the position of the fluorine atoms in both series of complexes ( F1 – F4 vs F5 – F6 and G1 – G4 vs G5 – F6 , see Schemes and ), from blue to blue-green.…”

“…Numerous chemical modifications allowing the control of the emission energy have been reported. For instance, in the case of the neutral iridium­(III) bis­[(4,6-difluorophenyl)-pyridinato- N,C 2′]­picolinate FIrpic, A (Figure ), the most studied bis-cyclometalated iridium complex, introduction of strong electron-withdrawing substituents such as perfluorocarbonyl, benzoyl, or diphenylphosphoryl groups (Figure , complexes B – D ) onto the phenyl ring at the C5-position allows to further blue-shift the emission, whereas the CF 3 –Firpic ( F1 , Figure ) derivative incorporating an electron-withdrawing substituent at the 5-position of the pyridine ring of dF-ppy displays a bathochromic shift of the emission when compared to the parent unsubstituted complex.…”

“…In this article, we extend our catalytic approach to prepare two families of Ir­(III) complexes, neutral ( F ) and cationic species ( G ) (see Figure ), containing new aromatically substituted C^N ligands based on 2-(2,4-difluorophenyl)-5-(trifluoromethyl)­pyridine ( 1) and 2-(3,5-difluorophenyl)-5-(trifluoromethyl)­pyridine ( 5 ) (Scheme ), by using regioselective Pd-catalyzed C–H bond arylations. Various aryl groups substituted at the para -position by an electron-withdrawing group (CN, CO 2 Et, C­(O)­Me) are readily incorporated, the regioselectivity being electronically controlled by the two fluorine atoms of pro-ligands 1 and 5 .…”

Computational Studies of Ruthenium and Iridium Complexes for Energy Sciences and Progress on Greener Alternatives

“…Iridium complexes have already been used successfully in the design of efficient phosphorescent emitters in OLEDs [59,60,61,62,57,63,64,17,65,66,67,68,69,70]. In particular, cyclometallated iridium(III) complexes have and are still in use as an OLED phosphors.…”