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The nanoLED, an electroluminescent device utilizing quantum dots (QDs), is expected to be a promising candidate for the next‐generation display. This paper presents a newly developed QD protection technology for cadmium‐free nanoLEDs that enables simultaneous achievement of high‐efficiency electroluminescence (EL) and long lifetime. The device which was prototyped by applying ZnSeTe blue QDs to an emissive layer demonstrated a maximum external quantum efficiency (EQE) of 21.0% and a luminance half‐lifetime (LT50) of 128,000 hours at 100 nits. These results indicate that cadmium‐free nanoLEDs can meet the requirements for display application in terms of both EL efficiency and reliability. [ABSTRACT FROM AUTHOR]

Crystallization of the verdazyl-based valence tautomeric ion [Co(dipyvd)2]2+ (where dipyvd is the radical ligand 1-isopropyl-3,5-di(2'-pyridyl)-6-oxoverdazyl) with a variety of different counterions results in materials that show varying degrees of valence tautomeric (VT) transition in the solid state. The X-ray structure of the SbF6 salt at 150 K reveals a localized structure for the S = 1/2 tautomer, with a Co3+ cation and distinct anionic and radical ligands. Comparison with the structure of the same material at 300 K reveals large structural changes in the ligand as a result of the valence tautomeric equilibrium. Data for the S = 3/2 form is less conclusive; X-ray spectroscopy on the PF6 salt suggests a degree of low spin Co2+ character for the S = 3/2 tautomer at very low temperature though this is inconsistent with EPR data at similar temperatures and structural information at 150 K. Magnetic measurements on the [BArF4]- and triflate salts in organic solvents show that the VT equilibrium is dependent on solvent and ion pairing effects. [ABSTRACT FROM AUTHOR]

We report and discuss the challenges to realize a nanoLED based display from the perspective of materials and processes. Additionally, we report on an active‐matrix nanoLED display using heavy metal free Quantum Dots (QDs) patterned by photolithography, realized by combining materials and process technology. [ABSTRACT FROM AUTHOR]

Electroluminescent QD‐EL devices based on InP and ZnTeSe quantum dots are one of the most promising future display technologies. With improvement in synthesis, we have developed high quantum yield environmental‐friendly quantum dots and through device optimization we have achieved efficiencies of 21.0% and 13.5% for red and blue QD‐ELs, respectively. In this paper, we report on the impact of the quasi‐cubic morphology of quantum dots to device efficiency performance. [ABSTRACT FROM AUTHOR]

Coordination of 1-isopropyl-3,5-dipyridyl-6-oxoverdazyl to cobalt results in a dication best described in the solid state as a high spin cobalt(II) ion coordinated to two radical ligands with an S = 3/2 ground state. On dissolution in acetonitrile, the cobalt(II) form equilibrates with a cobalt(III) valence tautomer with an S = 1/2 ground state. [ABSTRACT FROM AUTHOR]

Reaction of nickel and zinc triflates with the tridentate leucoverdazyl 1-isopropyl-3,5-di (2'-pyridyl)-6-oxo-2H-tetrazine (dipyvdH) and triethylamine resulted in the neutral coordination compounds M(dipyvd) 2 (M = Ni,Zn). In acetonitrile, both compounds undergo two one electron oxidation processes, Zn (dipyvd) 2  at -0.28 V and -0.12 V and Ni(dipyvd) 2  at -0.32 V and -0.15 V vs ferrocene/ferricenium. Oxidations are ligand based resulting in an intermediate mixed valence species and a cationic bis(verdazyl) compound respectively. Oxidation of the ligand changes a localized, antiaromatic, non-planar 8π electron anion to a planar, delocalized 7π electron radical. The change in ligand structure results in an increase in the octahedral ligand field splitting from 10,500 cm -1 to ∼13,000 cm -1 , suggesting an increase in the pi acceptor character of the ligand. In the mixed valence species, spectroscopic data suggests minimal interaction between ligands mediated by the metal center; i.e., these are class I-II systems in the Robin-Day classification., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Fleming, Vu, Brook, Agrestini, Pellegrin and DaRos.)