Iridium(III) Emitters Based on 1,4-Disubstituted-1H-1,2,3-triazoles as Cyclometalating Ligand: Synthesis, Characterization, and Electroluminescent Devices

Abstract

A series of blue and blue-green emitters based on neutral bis- and tris-cyclometalated Ir(III) complexes with 1-benzyl-4-(2,6-difluorophenyl)-1H-1,2,3-triazole (dfptrBn) as cyclometalating ligand is reported. The bis-cyclometalated complexes of the type [Ir(dfptrBn)(2)(L(^)X)] with different ancillary ligands, L(^)X = picolinate (pic) (2) or 2-(5-(perfluorophenyl)-2H-1,2,4-triazol-3-yl)pyridine (pytrF(5)) (3), are described and their photophysical properties compared with the analogous complexes containing the archetypal 2-(2,4-difluorophenyl)pyridinato (dfppy) as cyclometaled ligand (C(^)N). Complex 2 exhibits a marked solvatochromic behavior, from 475 nm in toluene to 534 nm in formamide, due to the strong MLCT character of its emissive excited state. Complex 3 displays a true-blue emission, narrower in the visible part than FIrpic. In addition, the homoleptic complex [Ir(dfprBn)(3)] (4) and the heteroleptic compounds with mixed arylpyridine/aryltriazole ligands, [Ir(dfptrBn)(2)(C(^)N)] (C(^)N = 2-phenylpyridinato (ppy) (5) or dfppy (6)), have been synthesized and fully characterized. The facial (fac) complex fac-4 is emissive at 77 K showing a deep-blue emission, but it is not luminescent in solution at room temperature similarly to their phenylpyrazole counterparts. However, the fac isomers, fac-5 and fac-6, are highly emissive in solution and thin films, reaching emission quantum yields of 76%, with emission colors in the blue to blue-green region. The photophysical properties for all complexes have been rationalized by means of quantum-chemical calculations. In addition, we constructed electroluminescent devices, organic light-emitting diodes (OLEDs) by sublimation of fac-6, and by solution processed polymer-based devices (PLEDs) using complexes fac-5 or fac-6 as dopants.

Functionalization of phosphorescent emitters and their host materials by main-group elements for phosphorescent organic light-emitting devices

“…28,270,410 Introduction of a C-F bond or a CF 3 group may modify the molecular packing style due to the existence of the FÁ Á ÁH-C interactions. [412][413][414][415][416] Besides, the charge injection/transporting properties of the related complexes can also be changed due to the altered MO levels. [412][413][414][415][416] Besides, the charge injection/transporting properties of the related complexes can also be changed due to the altered MO levels.…”

Analyzing the Relation between Structure and Aggregation Induced Emission (AIE) Properties of Iridium(III) Complexes through Modification of Non‐Chromophoric Ancillary Ligands

“…The photoluminescence spectra were also studied in deaerated dichloromethane at room temperature in order to assess the impact of using less polar solvents (Figure ). CT states are frequently found to be stabilized upon increasing the solvent polarity . This effect is commonly known as positive solvatochromism.…”

Cyclometalated Iridium(III) Complexes with Deoxyribose Substituents

“…Ligand 7 recurs in all complexes in this work. [54][55][56] Metallonucleosides were prepared by the treatment of 7 with known, chloro-bridged iridiumA C H T U N G T R E N N U N G (III) dimers. An example appears in Scheme 2.…”