Efficient near infrared light emitting electrochemical cell (NIR-LEEC) based on new binuclear ruthenium phenanthroimidazole exhibiting desired charge carrier dynamics

Abstract

Near-infrared light-emitting electrochemical cell (NIR-LEEC) has emerged as a new and promising lighting sourcewhich could serve as low-cost alternatives in NIR light-emitting sources which are typically expensive. LECs were also shown advantages such as light weight, simplicity and low operation voltages. However, only a few examples of NIR-LEEC are reported in which external quantum efficiency(EQE) of devices limited to 0.1%. Here, we report, efficient NIR-LEEC based of two novel binuclear ruthenium phenanthroimidzole complex which differ by employing the type of ancillary ligand including 2, 2′bipyridine (bpy) (B1) and 4, 4′ dimethyl bpy (B2) that realize maximum EQE of 0.14 and 0.68% and extremely long excited state lifetimes of 220 and 374 ns for thin film were estimated, respectively, indicating that influences of substitution on ancillary ligand. Moreover, this substitution dramatically influences other electroluminescence metrics including decreasing turn on voltage from 4.5 to 3.1 V, increasing maximum luminance (Lmax) from 193to 742 cd.m−2 and increasing lifetime from 539 to 1104 second, which are the best value among the binuclear ruthenium polypyridyl complexes to date.

Incorporation of Designed Donor–Acceptor–Donor Segments in a Host Polymer for Strong Near-Infrared Emission from a Large-Area Light-Emitting Electrochemical Cell

“…However, for several applications a high-frequency power supply is not practical. In this context, it is important that Bideh and Shahroosvand were able to record a luminance of 742 cd/m 2 at 690 nm at a constant current density of 222.4 mA/cm 2 from an LEC using a Ru-complex as the emitter; unfortunately, the operational lifetime was short at <20 min. Our group recently reported an LEC comprising a metal-free alternating copolymer as the emitter, which delivered stable NIR emission at 129 μW/cm 2 and 705 nm when driven by a constant current density of 74.5 mA/cm 2 …”

Ruthenium polypyridyl complex-containing bioconjugates

“…reported sterically hindered complexes 10, 11a, 11b and 12 (Fig. 6), by systematically adding methyl groups on the bpy ligand(s) [from zero (10) to two (11a and 11b) and to four (12)]. [50] All complexes were obtained as racemic mixtures, with the Λ as the major isomer, except for the most hindered 12, which was obtained as the single Λ-isomer.…”

“…1 V and three reduction peaks (the first two reversible and the last one quasi-reversible), corresponding to each of the bpy ligands. In addition, the versatility of Ru(II) polypyridyl complexes as energy donors, electron acceptors and electron donors along with their great stability in solution, tunability and ease of synthesis [1] make them excellent candidates as catalysts, [2][3][4] solar dyes, [5][6][7] in light-emitting electrochemical cells [8][9][10] and light-emitting diodes, [11] as well as in many biological applications such as anticancer agents [11][12][13][14][15] or photosensitizers for photodynamic therapy (PDT). [16][17][18][19][20] Fig.…”

Recent Advances on Metal-Based Near-Infrared and Infrared Emitting OLEDs

“…This work is notably justified by the fact that LECs based on complexes comprising phenanthroimidazole ligands often lack the acceptable device stability for future applications, which could be improved by using di-nuclear complexes [109,110]. However, examination of LECs characteristics revealed that this challenge could not overcome with Ru-19 and Ru-20 , the time for LECs to reach half of the initial luminance being of only 539 and 1104 s for Ru-19 and Ru-20 -based devices, respectively (See Figure 7 and Table 4) [111]. From this work, it can be, therefore, concluded that the design of polynuclear Ru-complexes requiring hard work from the synthetic point of view is useless and non-adapted for the design of long-living LECs.…”