Stable and Efficient Solid‐State Light‐Emitting Electrochemical Cells Based on a Series of Hydrophobic Iridium Complexes

Abstract

Light-emitting electrochemical cells (LECs) based on ionic transition-metal complexes (iTMCs) exhibiting high effi ciency, short turn-on time, and long stability have recently been presented. Furthermore, LECs emitting in the full range of the visible spectrum including white light have been reported. However, all these achievements were obtained individually, not simultaneously, using in each case a different iTMC. In this work, device stability is maintained by employing intrinsically stable ionic iridium complexes, while increasing the complex and the device quantum yields for exciton-to-photon conversion. This is done by sequentially modifying the archetype ionic iridium complex [Ir(ppy) 2 (bpy)][PF 6 ], where Hppy is 2-phenylpyridine and bpy is 2,2'-bipyridine, with methyl and phenyl groups on the bpy ligand. A full photophysical and theoretical description of a series of four complexes, including the archetype as a reference, is presented and their performance in LECs is characterized. Upon selecting suitable substituents, a twofold increase is obtained in the photoluminescence quantum yield in a solid fi lm. This is refl ected in a significant increase in the effi ciency over time curve for LECs using this complex.

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

“…[197] For example, LECs using complex 46 ( Figure 30) showed EL maxima at l = 555 nm with CIE coordinates x = 0.436; y = 0.549. In contrast, substitution of these positions by one or two phenyl groups as for example in complexes 31 and 32 ( Figure 25) does not cause any spectral change.…”

From Ligand to Phosphor: Rapid, Machine‐Assisted Synthesis of Substituted Iridium(III) Pyrazolate Complexes with Tuneable Luminescence

“…Using an excitation wavelength of 380 nm, the complexesr evealed ab road,f eatureless emission peak that ranged between 510-560 nm ( Figure 5), depending upon the nature of the pyrazolel igand. For comparison, [Ir(ppy) 2 (bipy)]PF 6 (ppy = 2-phenylpyridine) emits at 602 nm from am ixed 3 MLCT/ 3 LLCT excited state; [19] the more closely related [Ir(ppz) 2 (bipy)]PF 6 (ppz = 2-phenylpyrazole)e mits at 563 nm in MeCN. [20] In this study,t he mostr edshifted emission was in- 2 (bipy)]BF 4 (meta substitution induced the highest energy emission at shortest wavelength).…”

Lumineszierende ionische Übergangsmetallkomplexe für leuchtende elektrochemische Zellen

“…[197] So hatten LECs mit dem Komplex 46 (Abbildung 30) EL-Maxima bei l = 555 nm (CIE-Koordinaten: x = 0.436, y = 0.549). Eine Substitution an gleicher Stelle mit einer oder zwei Phenylgruppen wie in den Komplexen 31 bzw.…”