The incorporation of magnetic impurities into semiconductor nanocrystals with size confinement promotes enhanced spin exchange interaction between photogenerated carriers and the guest spins. This interaction stimulates new magnetooptical properties with significant advantages for emerging spin-based technologies. Here we observe and elaborate on carrier−guest interactions in magnetically doped colloidal nanoplatelets with the chemical formula CdSe/Cd 1−x Mn x S, explored by optically detected magnetic resonance and magneto-photoluminescence spectroscopy. The host matrix, with a quasi-type II electronic configuration, introduces a dominant interaction between a photogenerated electron and a magnetic dopant. Furthermore, the data convincingly presents the interaction between an electron and nuclear spins of the doped ions located at neighboring surroundings, with consequent influence on the carrier's spin relaxation time. The nuclear spin contribution by the magnetic dopants in colloidal nanoplatelets is considered here for the first time.
Flexible
semiconductor materials, where structural fluctuations
and transformation are tolerable and have low impact on electronic
properties, focus interest for future applications. Two-dimensional
thin layer lead halide perovskites are hailed for their unconventional
optoelectronic features. We report structural deformations via thin
layer buckling in colloidal CsPbBr
3
nanobelts adsorbed
on carbon substrates. The microstructure of buckled nanobelts is determined
using transmission electron microscopy and atomic force microscopy.
We measured significant decrease in emission from the buckled nanobelt
using cathodoluminescence, marking the influence of such mechanical
deformations on electronic properties. By employing plate buckling
theory, we approximate adhesion forces between the buckled nanobelt
and the substrate to be
F
adhesion
∼
0.12 μN, marking a limit to sustain such deformation. This work
highlights detrimental effects of mechanical buckling on electronic
properties in halide perovskite nanostructures and points toward the
capillary action that should be minimized in fabrication of future
devices and heterostructures based on nanoperovskites.
We observe that different growth conditions and resulting morphologies of CsPbBr3 nanocrystals yield opposite stokes shift size-dependent trends. This emphasizes the different photo-physics for quantum-confined nanoplate and nanocube morphologies.
Incorporating magnetic ions into semiconductor nanocrystals has emerged as a prominent research field for manipulating spin-related properties. The magnetic ions within the host semiconductor experience spin-exchange interactions with photogenerated carriers and are often involved in the recombination routes, stimulating special magneto-optical effects. The current account presents a comparative study, emphasizing the impact of engineering nanostructures and selecting magnetic ions in shaping carrier–magnetic ion interactions. Various host materials, including the II–VI group, halide perovskites, and I–III–VI2 in diverse structural configurations such as core/shell quantum dots, seeded nanorods, and nanoplatelets, incorporated with magnetic ions such as Mn2+, Ni2+, and Cu1+/2+ are highlighted. These materials have recently been investigated by us using state-of-the-art steady-state and transient optically detected magnetic resonance (ODMR) spectroscopy to explore individual spin-dynamics between the photogenerated carriers and magnetic ions and their dependence on morphology, location, crystal composition, and type of the magnetic ion. The information extracted from the analyses of the ODMR spectra in those studies exposes fundamental physical parameters, such as g-factors, exchange coupling constants, and hyperfine interactions, together providing insights into the nature of the carrier (electron, hole, dopant), its local surroundings (isotropic/anisotropic), and spin dynamics. The findings illuminate the importance of ODMR spectroscopy in advancing our understanding of the role of magnetic ions in semiconductor nanocrystals and offer valuable knowledge for designing magnetic materials intended for various spin-related technologies.
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