Low-voltage, high-brightness and deep-red light-emitting electrochemical cells (LECs) based on new ruthenium(ii) phenanthroimidazole complexes

Abstract

Light-Emitting Electrochemical Cells (LECs) with a simple device structure ITO/Ru complex/Ga:In were prepared by using heteroleptic ruthenium(ii) complexes containing 2-(2-hydroxyphenyl)-1-(4-bromophenyl)-1h-imidazo[4,5-f][1,10]phenanthroline (hpbpip) as the π-extended ligand. After ancillary ligand modification, the [Ru(hpbpip)(dmbpy)2](ClO4)2 complex shows a deep red electroluminescence emission (2250 cd m(-2) at 6 V) centered at 685 nm, 65 nm red-shifted compared to the [Ru(bpy)3](ClO4)2 benchmark red-emitter at a very low turn voltage (2.6 V), demonstrating its potential for low-cost deep-red light sources. Moreover, the PL quantum yield of the [Ru(hpbpip)(bpy)2](ClO4)2 complex was revealed to be higher (0.121) than the benchmark standard [Ru(bpy)3](2+) (0.095).

Long-Lived Polypyridyl Based Mononuclear Ruthenium Complexes: Synthesis, Structure, and Azo Dye Decomposition

“…The coordination chemistry of ruthenium polypyridyl complexes has witnessed a rapid progress since the inception of [Ru­(bpy) 3 ] 2+ in the scientific community. The longer excited-state lifetime of such system leading to exciting photophysical and photochemical properties makes them attractive for various applications in the diverse areas of chemistry and biology such as dye-sensitized solar cells (DSSCs), − light emitting electrochemical cells (LEECs), − sensors, − catalysis, − water oxidation/reduction catalysts, − molecular probe for DNA structure (light switch for DNA), − photodynamic therapy, ,, cellular imaging, ,− and fundamental studies of photoinduced electron and energy transfer processes. − Such properties of the metal complexes can be manipulated by proper design of ligand framework. In this context, polypyridyl dppz based ligands have become the most attractive considering their stability, tunable photophysical and photochemical properties with strong metal to ligand charge transfer (MLCT) transitions, and efficient intercalation with DNA base pair and allow the formation of adducts with functional groups of base pairs. − ,− ,− A large variety of [(bpy) 2 Ru II (N ∧ N)] complexes with the aforementioned dppz based ligand frameworks have been developed and studied. − ,− ,− In most of the cases the dppz based ligands are flat and rigid with extended ...…”

Synthesis, Study, and Application of Pd(II) Hydrazone Complexes as the Emissive Components of Single-Layer Light-Emitting Electrochemical Cells

“…Complex 1 emits at λ max = 549 nm, and the PL spectrum of 2 has a very similar λ max = 553 nm. Studies in both solution and thin films revealed that the photoluminescence quantum yields (PLQYs) of 1 and 2 decrease slightly in the solid state. , The PL maxima in the thin films are red-shifted by about 50–60 nm when compared to the solution data which is attributed to both the change of emissive excited state and concentration effects in the solid state. − Furthermore, the ionic complex 2 exhibits a significantly higher PLQY versus the neutral compound 1 ( vide infra ). The PLQYs of 1 and 2 were also compared to other reported Pd­(II) complexes.…”

High-Efficiency Deep-Red Light-Emitting Electrochemical Cell Based on a Trinuclear Ruthenium(II)–Silver(I) Complex

“…The 1 H NMR comparison of ligand and complexes has confirmed the formation of ECH 3 + and E 2 Ag + . By comparing the NMR spectra of the ligands with those of similar compounds, , the signal of the H6 proton of the pyridine ring at δ = 8.55 as a doublet is assigned to phenanthroimidazole ligand. Because of electron-withdrawing nature of methylpyridinium, this signal in the CH 3 + was shifted downfield (δ = 9.35).…”