Aggregation-Induced Enhanced Emission-Active Zinc(II) β-Diketiminate Complexes Enabling High-Performance Solution-Processable OLEDs

Abstract

Earth-abundant and cheaper zinc-based organometallic molecules as luminophores are drawing significant research attention for solid-state lighting devices. In this paper, we report two air-stable zinc complexes, where the zinc is coordinated to two sterically encumbered β-diketiminate ligands in a tetrahedral geometry. In such a geometry, eight phenyl/aryl rings from the ligand backbones are oriented in a propeller shape, augmenting the restricted rotation of the putative rings. Such an architecture harnesses aggregation-induced emission behavior with an excellent solid-state emission property. The rigidity of these molecules reduces the possibility of non-radiative transitions and makes them excellent fluorescence emitters. Both molecules exhibit electroluminescence (EL) in the yellowish-green region of the visible spectrum. We have utilized these molecules as emitters to fabricate multilayered organic light-emitting diode (OLED) devices. The emitter Zn-I in host m-MTDATA exhibits EL with a maximum external quantum efficiency of 4.4%. Among the handful of zinc-based OLEDs, the performance of this emitter is very commendable with power and current efficacies of 15.2 lm W–1 and 12.1 cd A–1, respectively, along with a brightness of 2426 cd m–2.

Zn(ii) complexes with thiazolyl–hydrazones: structure, intermolecular interactions, photophysical properties, computational study and anticancer activity

“…It is well documented that the crystal packing often renders a tremendous influence on the photoluminescence properties of the molecules. [63][64][65] This includes also solvatomorphism, caused by different solvents of crystallization. It seems that the non-emissive nature of 2-Cl and 3-Cl is related to their symmetry, which in turn resulted in the formation of an overall different crystal packing environment in comparison to the nitrate-based analogues, as crystal packing analysis and interaction energies showed.…”

Zinc(II) Complexes with Triplet Charge-Transfer Excited States Enabling Energy-Transfer Catalysis, Photoinduced Electron Transfer, and Upconversion

“…Possible applications of fluorescent Zn II compounds in electroluminescence, ,− including organic light-emitting diodes (OLEDs), − circularly polarized luminescence, sensing, or cell imaging, have attracted interest . Similarly, aggregation-induced emission − as well as thermally activated delayed fluorescence (TADF) received substantial attention with Zn II complexes. − …”

Bimodal photocatalytic behaviour of a zinc β-diketiminate: application to trifluoromethylation reactions

“…In the pursuit of developing photocatalysts based on 3d metals, we recently discovered a zinc β-diketiminate molecule 1 , where zinc is trapped in a pseudo-tetrahedral environment between two Ph,Ph NacNac ligands. 8 Such β-diketiminates are a robust scaffold, but their direct use in promoting photocatalytic reactions is rare. 9 We have previously observed a long-lived excited state ( 1 π–π*) for the molecule, which is also strongly oxidizing in nature .…”