A Zinc(II) Benzamidinate N‐Oxide Complex as an Aggregation‐Induced Emission Material: toward Solution‐Processable White Organic Light‐Emitting Devices

Abstract

The synthesis, characterization, photophysical and redox properties of a dinuclear complex Zn 2 (AMOX) 4 (AMOX = 4-bromo-N,N′-diphenylbenzamidinate N-oxide) are highlighted. This compound is a first example of a novel class of aggregation-induced emission (AIE) materials. Noticeably, solution-processed white-green organic light-emitting diodes were fabricated using this complex as dopant in a co-host matrix in the [a] 4324 gands. This distinction indicates that the energy of the LUMO can be fine-tuned by modifying the C-aryl substituents with EW/ED groups. The TD-DFT calculations for 1 ( Figure S10, Table Eur.

Recent Advances in Solid‐State Lighting Devices Using Transition Metal Complexes Exhibiting Thermally Activated Delayed Fluorescent Emission Mechanism

“…Zinc(II) compounds are used in OLEDs as in various applications, such as emitters, host materials, and hole injection layers. [ 86,175 ] A number of OLEDs including WOLEDs using Zinc(II) complexes as emitters have been reported by different groups [ 29,176–179 ] ; however, no TADF Zn(II) complex was reported until 2015 when Adachi and co‐workers published the first examples in green OLEDs (Table 9 and Scheme ). [ 29 ] These new TADF complexes showed very high PLQY of 78.4% and 58.4% with Φ TADF = 66.1% and 48.1% for Zn1 and Zn2 respectively (Table 8).…”

Efficient white polymer light-emitting diodes (WPLEDs) based on covalent-grafting of [Zn2(MP)3(OAc)] into PVK

“…The obtained quantum yield of up to 18.4% for the ideal white-light point II-D ( x = 0.323, y = 0.333; CCT of 8533 K and CRI of 75) under excitation at 345 nm is the highest among all reported Zn 2+ -complex-doping systems. 22,23 The 2.8 ns lifetime of the PVK-incorporated blue light ( λ em = 419 nm) and the [Zn2(MP)3(OAc)] -centered yellow light ( λ em = 540 nm) lifetime of 77 ns confirm that the optimal dichromatic white light should have unambiguous fluorescence characteristics. Interestingly, as for the polymer Poly(NVK-co-[Zn2(MP)3(OAc)]) (300 : 1), although all the integrated points III-A–D ( x = 0.258–0.265, y = 0.296–0.305) also fall into the blue–white-light regime (Fig.…”

“…First, besides a lower V on of 6.0 V, the dichromatic white light ( Fig. 5(d and e) ; CIE coordinates of x = 0.325–0.329, y = 0.300–0.310; CCTs of 7050–7318 K and CRIs of 82–84) can be stable within an extended applied bias voltage range of 6.0–15.0 V, and L Max (46.2 cd m −2 ) is slightly increased with a lower J of 6.7 mA cm −2 at 15.0 V. More importantly, its maximum efficiencies ( η Max c = 13.0 cd A −1 , η Max p = 6.1 lm W −1 and η Max EQE = 9.2%) reformed almost 5–6 times more than those of the WPLED-I and are the best (Table S7 † ) among reported Zn( ii )-complex-based WOLEDs 16–20 /WPLEDs, 22,23 to our knowledge. Furthermore, within the stable illuminating range, the high efficiencies ( η c = 9.1 cd A −1 , η p = 4.4 lm W −1 and η EQE = 6.8%) are maintained, with distinctively weaker efficiency roll-off ( ca .…”

“… 16–18 Nonetheless, besides the inevitable high cost of the vacuum-deposition procedure, unsatisfactory device performance-based crystallization and discrepant components-induced white-light instability pose problems for the two strategies. Convincingly, the circumvention of these problems, to some extent, cannot depend on Zn( ii )-based white-light-emitting coordination polymers 21 with a lack of inherent processing ability, but can only rely on the doping of Zn( ii )-complexes 22 and/or sensitizers 23 into a polymeric host with a deep LUMO–HOMO bandgap for solution-processable and large-area WPLEDs. The attractive η c of 14.67 cd A −1 , η p of 6.58 lm W −1 and η EQE of 6.88% are traded with detrimental deficiency with the inferior CIE (Commission Internationale de l’Eclairage) chromaticity coordinate of (0.42, 0.44) and unstable white light from a phase separation arises during incompatible multi-component integration.…”

Zinc (II) and AIEgens: The “Clip Approach” for a Novel Fluorophore Family. A Review

“…The electroluminescence (EL) properties achieved by zinc (II) complexes were checked: peak luminance (L max ) of 3589 cd m −2 , maximal external quantum efficiency (η ext ) of 1.46%, maximum current efficiency (η L ) of 4.1 cd A −1 , and maximal power efficiency (η P ) of 3.8 lm W −1 . Garry S. Hanan and coworkers in 2018 [ 121 ] synthesised a dinuclear complex of zinc (II) with 4-bromo- N , N ′-diphenylbenzamidinate N-oxide. This compound is a Zn AIEgen and was used as a dopant in a co-host matrix of the emissive layer used in the fabrication of a solution-processed white–green WOLED.…”