Ternary zinc complexes as electron transport and electroluminescent materials

A Review: Blue Fluorescent Zinc (II) Complexes for OLEDs-A Last Five-Year Recap

Blue emissions in organic light-emitting diodes (OLEDs) are essential for their application in solid-state lighting and full-colour flat panel displays. On the other hand, high-power blue emitters are still uncommon, especially those that can achieve the Commission Internationale de l'Eclairage (CIE, X, Y) coordinates of (0.14, 0.08) in the National Television System Committee (NTSC) blue standard and have high external quantum efficiencies (EQE) of more than 5% because their molecular design presents an enormous challenge. Therefore, creating effective, stable, pure, and deep blue fluorescent materials is vital. Here, it is addressed how useful blue fluorescent Zn (II) complexes are for making organic light-emitting diodes (OLEDs). Utilizing Zn (II) complexes is appealing because of their favourable luminous characteristics, acceptance and mobility, and affordability. This mini-review article aims to provide an overview of Zn (II) complexes that emit blue fluorescent light and have been reported since 2018, while highlighting the unique qualities that make them appropriate OLED materials.

Efficient white polymer light-emitting diodes (WPLEDs) based on covalent-grafting of into PVK

Thanks to the straightforward white light of single grafting-type polymers based on earth-abundant Zn(ii)-complexes, producing cost-effective flexible WOLEDs/WPLEDs with good device performance remains a formidable challenge. Herein, by using the polymer Poly(NVK-co-[Zn2(MP)3(OAc)]) with excellent physical properties for single-layer WPLEDs, record-high efficiencies (η ^Max _c = 13.0 cd A^-1, η ^Max _p = 6.1 lm W^-1 and η ^Max _EQE = 9.2%) and low (ca. 25%) efficiency roll-off compared to previous organo-Zn²⁺-based WOLEDs/WPLEDs are realized. This finding renders single Zn(ii)-complex-grafted polymers a new route to low-cost and large-area flexible WPLEDs for potential full-colour flat displays.

Heteroleptic Zn(II) Complexes: Synthesis, Characterization and Photoluminescence Properties

Heteroleptic Zn (II) complexes containing 8-hydroxy quinoline as preliminary ligand and pyrazolone based derivatives as secondary ligand were synthesized and their structures confirmed by NMR, Mass, FT-IR, UV-vis and Elemental analysis. Theses complexes show good photoluminescence properties in solid and solution state in the range of 505-544 nm with quantum yield 0.38 to 0.50. Whereas these complexes also show good life time in the range of 0.037 to 0.043 ms. These complexes show shift in the range of 25-30 nm. in different polar and nonpolar solvents due to intramolecular charge transfer (ICT). The bandgap of these complexes is around ~2.60 eV. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of all complexes are determine by cyclic voltammetry it obtained in the range of and ~ (-5.29 eV) and ~(-2.69 eV). The energy band gap, frontier molecular orbitals (FMO) energy levels and geometrical structures were optimized using density functional theory (DFT) with B3LYP/6-31G* basic set on Spartan'18 software. All complexes displayed high thermal stability. Graphical Abstract Donor-Bridge- Accepter (D-B-A) based Heteroleptic Zn(II) complexes for OLEDs application.