Luminescence and Covalency in Ytterbium-Doped CrX (X = Cl, Br, I) van der Waals Compounds.

The layered 2D van der Waals ferromagnets CrX (X = Cl, Br, I) show broad d-d photoluminescence (PL). Here we report preparation, structural characterization, and spectroscopic studies of all three CrX compounds doped with the optical impurity, Yb. EXAFS measurements show very similar Cr K-edge and Yb L-edge data for each doped compound, and good fits of the latter are obtained for structures having Yb occupying substitutional octahedral sites.

Direct Patterning of Perovskite Nanocrystals on Nanophotonic Cavities with Electrohydrodynamic Inkjet Printing.

Overcoming the challenges of patterning luminescent materials will unlock additive and more sustainable paths for the manufacturing of next-generation on-chip photonic devices. Electrohydrodynamic (EHD) inkjet printing is a promising method for deterministically placing emitters on these photonic devices. However, the use of this technique to pattern luminescent lead halide perovskite nanocrystals (NCs), notable for their defect tolerance and impressive optical and spin coherence properties, for integration with optoelectronic devices remains unexplored.

Two-Dimensional van der Waals Nanoplatelets with Robust Ferromagnetism.

We have synthesized unique colloidal nanoplatelets of the two-dimensional (2D) van der Waals ferromagnet CrI and have characterized these nanoplatelets structurally, magnetically, and by magnetic circular dichroism spectroscopy. The CrI nanoplatelets have lateral dimensions of ∼25 nm and thicknesses of only ∼4 nm, corresponding to just a few CrI monolayers. Magnetic and magneto-optical measurements demonstrate robust 2D ferromagnetic ordering with Curie temperatures similar to bulk CrI, despite their small size.

Microcolumn lanthanide separation using bis-(2-ethylhexyl) phosphoric acid functionalized ordered mesoporous carbon materials.

Adjacent lanthanides are among the most challenging elements to separate, to the extent that current separations materials would benefit from transformative improvement. Ordered mesoporous carbon (OMC) materials are excellent candidates, owing to their small mesh size and uniform morphology. Herein, OMC materials were physisorbed with bis-(2-ethylhexyl) phosphoric acid (HDEHP) and sorption of Eu was investigated under static and dynamic conditions.

Anion Exchange and the Quantum-Cutting Energy Threshold in Ytterbium-Doped CsPb(ClBr ) Perovskite Nanocrystals.

Colloidal halide perovskite nanocrystals of CsPbCl doped with Yb have demonstrated remarkably high sensitized photoluminescence quantum yields (PLQYs), approaching 200%, attributed to a picosecond quantum-cutting process in which one photon absorbed by the nanocrystal generates two photons emitted by the Yb dopants. This quantum-cutting process is thought to involve a charge-neutral defect cluster within the nanocrystal's internal volume. We demonstrate that Yb-doped CsPbCl nanocrystals can be converted postsynthetically to Yb-doped CsPb(ClBr ) nanocrystals without compromising the desired high PLQYs.