Structure–Property Relationship in Amber Color Light-Emitting Electrochemical Cell with TFSI Counteranion: Enhancing Device Performance by Different Substituents on N^∧N Ligand

Abstract

Amber color emitting novel Ir(III) complexes were synthesized: [Ir-(Meppy) 2 (Fpbpy)][PF 6 ] (1bPF 6 ), [Ir(Meppy) 2 (Fpbpy)][TFSI] (1bTFSI), [Ir-(Meppy) 2 (MeObpy)][PF 6 ] (2bPF 6 ) and [Ir(Meppy) 2 (MeObpy)][TFSI] (2bTFSI), where Meppy = 2-(p-methylphenyl)-pyridine (b), Fpbpy = 4,4′-bis(4-fluorophenyl)-2,2′-bipyridine(1), and MeObpy = 4,4′-bis(4-methoxy)-2,2′-bipyridine (2). The photophysical and X-ray results showed that the complexes have aggregation-induced phosphorescent emission (AIPE) and a salt-induced polymorphism effect. The highest photoluminescence intensity was observed in complex 2bTFSI compared to other complexes in the solid state. Their theoretical absorption and phosphorescence emission transitions in acetonitrile were also investigated by using double-and triple-ζ basis sets with B3LYP and PBE0 hybrid functional. The best lightemitting electrochemical cell (LEC) performance was exhibited by complex 2bTFSI, and the data obtained were as follows: Luminance, current density, luminous efficiency, turn-on time, power efficiency, and external quantum efficiency were measured as 16 156 cd/m 2 , 554 mA/ cm 2 , 8.49 cd/A, 17 s, 3.95 lm/W and 6.37%, respectively. The investigation of crystallographic characteristics have shown that the LEC performance of these complexes depends on cationic−anionic interaction which has a significant influence on molecular stacking of the molecules. Because, complex 2bTFSI, with weak cationic−anionic interactions, shows strong π•••π stacking interactions between the adjacent molecules, it is the best lighting application candidate among the complexes.

Facile generation of thenil and furil based blue emitters for the fabrication of non-doped and solution-processed light-emitting electrochemical cells

“…This kind of smooth and homogenous morphology boosts the LEC performance by promoting more electron transfer. 2 ThAm coated thin film showed a lower rms value than FuAm , which could potentially improve charge recombination, resulting in a superior device efficiency than that of the FuAm based LEC.…”

“…The solid-state lighting technology comes with a lot of advantages like the light production in the visible range with a low heat conversion, extended lifetime, less energy consumption and better efficiency. 2 Moreover, it does not include any toxic materials like lead or mercury making it more eco-friendly and promotes the design of flexible structures. 2…”

“…2 Moreover, it does not include any toxic materials like lead or mercury making it more eco-friendly and promotes the design of flexible structures. 2…”

Full Solution Process of a Near-Infrared Light-Emitting Electrochemical Cell Based on Novel Emissive Ruthenium Complexes of 1,10-Phenanthroline-Derived Ligands and a Eutectic Alloy as the Top Electrode

“…In recent years, solid-state red to near-infrared (NIR)-emitting materials as candidates of light sources have attracted a lot of attention, which can be used for bioimaging and labeling of human body tissues. − In addition, light-emitting electrochemical cells (LECs) have emerged as a viable option for inexpensive optical applications in the last two decades. − So far, many molecules, including polymers, − organic small molecules, , macromolecules, ionic transition-metal complexes (iTMCs), − and quantum dots, , have been used as emitters in LECs. However, the unique photophysical properties of iTMCs, such as the high external quantum efficiency (EQE) and long half-time, especially Ir­(III) organometallic complexes, , Cu­(I) complexes, , and Ru­(II) polypyridine complexes, have led to the design of new derivatives. Nevertheless, various iTMCs such as Pd­(II), Zn­(II), Pt­(II), Ir­(III)–Au­(I), and Ru­(II)–Ag­(I) have also been used in LECs as an emitter. ,,,, In film-processing, iTMCs are very useful because a single component is used in the film, and it acts as a charge transport and emissive material.…”

Phenanthroimidazole as molecularly engineered switch for efficient and highly long-lived light-emitting electrochemical cell

“…Another concern about iTMC-emitters is that they exhibit severe phosphorescence concentration-quenching in the solid state as a result of their relatively long triplet lifetimes which markedly suppresses the phosphorescence efficiency of the emissive layers and thereby the LEC performances. It has been shown that enclosing bulky groups (such as phenyl) to peripheral ligands can provide steric hindrance and effectively reduces self-quenching of iridium complex emitters in the solid-state form [47][48][49][50] . Phenanthroimidazole (PI) molecules with a specific structure and supreme photophysical features are frequently used as small molecules, ancillary ligands, and as a host material in optoelectronic devices.…”