Imidazole derivatives for efficient organic light-emitting diodes

Abstract

Since the first development of organic light-emitting diodes (OLEDs) in 1987, imidazole derivatives, mainly including phenanthroimidazole (PI) and benzimidazole (BI), have increasingly attracted attention. Their strong electron-withdrawing properties make them suitable for emitters, hosts, and electron-transporting materials (ETMs). In this review, an overview of the recent developments regarding OLEDs based on imidazole derivatives, especially the relationship between the molecule structure and the device performance as fluorescent and host materials, is given.

Synthesis of Mono- and Polyazole Hybrids Based on Polyfluoroflavones

“…As is known, aryl-azole scaffolds are considered as promising materials for OLEDs [ 46 , 47 , 48 , 49 ]; therefore, we recorded the photoluminescence spectra for poly(azolyl)-substituted flavones 28 – 31 and formerly synthesized penta(pyrazolyl)-substituted analogue 32 [ 26 ]. It was found that 2-[4-(imidazolyl)-2,3,5,6-tetra(pyrazolyl)- and penta(pyrazolyl)-substituted flavones 28 and 32 exhibit emission in the solid state under UV-irradiation, in contrast to poly(triazolyl)-containing derivatives 29 and 31 .…”

“…The way to more effective medicines is through the synthesis of azole hybrids with other pharmacophores [ 27 , 43 , 44 , 45 ], which might be flavones, with them having a pyran framework that determines their great potential as antiviral antibacterial agents. Polyazole hybrid derivatives are also given special attention due to their potential applications as electron-transporting materials, emitters, and host materials in OLEDs, the most attractive products of organic electronics [ 46 , 47 , 48 ]. In this regard, the synthesis of hybrid compounds based on the flavone and azole cycles seems to be a prominent problem, which can be solved by the S N Ar reaction of polyfluorinated flavones with azoles.…”

Novel Imidazole Liquid Crystals; Experimental and Computational Approaches

“…Imidazole derivatives have a wide range of industrial applications. It is the perfect building block for nonlinear optical materials because of its great electron-withdrawing potential and good coplanarity [ 9 , 10 , 11 ]. Other uses for imidazolium salts include coating metal nanoparticles to offer antimicrobial action, removing metal ions from aqueous solutions, and producing oriented liquid crystals [ 12 ].…”

Synthesis and Characterization of Blue-emitting Donor N-Substituted Tetraphenylimidazole Derivatives

“…Imidazole derivatives have been widely explored as both electron-transporting and emitter materials for OLEDs. [21,22] The two nitrogen atoms within the imidazole ring, N1 and N3, possess distinct chemistry and confer bipolar character to the imidiazole with N1 being nucleophilic, while N3 is part of a p-accepting imine (Figure 1a). This N3 nitrogen deepens the LUMO energy of 1,2,4,5-tetraphenylimidazole (TPI) to -0.76 eV, which is comparable to that of OXD (-0.55 eV, PBE0/6-31G(d,p)).…”

“…To date, there are just a handful examples reported employing donors at the N1 position of imidazole. [21,22,25,31] However, most of these examples also contain substituents at C2 and it is these that dominate the photophysics of the molecule. To study the substituent effect on the imidazole electronics, we designed three new donor-imidazole hybrid materials, 9,9-dimethyl-10-(4-(2,4,5-triphenyl-1H-imidazol-1-yl)phenyl)-9,10-dihydroacridine (DMAC-TPI), 10-(4-(2,4,5-triphenyl-1H-imidazol-1yl)phenyl)-10H-phenoxazine (PXZ-TPI), and 10-(4-(2,4,5-triphenyl-1H-imidazol-1-yl)phenyl)-10Hphenothiazine (PTZ-TPI), where the donors were connected to tetraphenylimidazole para to the N1 phenylene.…”