Carrier spins in semiconductor nanocrystals are promising candidates for quantum information processing. Using a combination of time-resolved Faraday rotation and photoluminescence spectroscopies, we demonstrate optical spin polarization and coherent spin precession in colloidal CsPbBr 3 nanocrystals that persists up to room temperature. By suppressing the influence of inhomogeneous hyperfine fields with a small applied magnetic field, we demonstrate inhomogeneous hole transverse spin-dephasing times (! ! *) that approach the nanocrystal photoluminescence lifetime, such that nearly all emitted photons derive from coherent hole spins. Thermally activated LO phonons drive additional spin dephasing at elevated temperatures, but coherent spin precession is still observed at room temperature. These data reveal several major distinctions between spins in nanocrystalline and bulk CsPbBr 3 and open the door for using metal-halide perovskite nanocrystals in spin-based quantum technologies.

The purpose of the research is to provide HR managers with some guidance, as they develop employee volunteer programs to meet specific workforce needs. Structured interviews were conducted with eight employees. The data suggest that employees who volunteer time believe that such experiences benefit them personally and improve their ability to perform their work duties. There were slight differences in program type, with those employees involved in programs characterized by high management support and commitment tending to perceive that they reap high overall rewards for their volunteer activities. The perceived impact of volunteer activities on employees included: an improved ability to cope with job challenges; the development of contacts and skills that can be used on the job; improved self‐esteem and a sense of pride. These factors can increase employees’ ability to be proactive problem solvers on the job.

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Inorganic–organic interfaces: a tutorial on using organic functional groups to enhance the performances and/or enable new functionality of inorganic nanomaterials.

CsPb(Cl 1−x Br x ) 3 (0 ≤ x ≤ 1) nanocrystals and thin films doped with a series of trivalent rare-earth ions (RE 3+ = Y 3+ , La 3+ , Ce 3+ , Gd 3+ , Er 3+ , Lu 3+ ) have been prepared and studied using variable-temperature and time-resolved photoluminescence spectroscopies. We demonstrate that aliovalent (trivalent) doping of this type universally generates a new and oftenemissive defect state ca. 50 meV inside the perovskite band gap, independent of the specific RE 3+ dopant identity or of the perovskite form (nanocrystals vs thin films). Chloride-to-bromide anion exchange is used to demonstrate that this near-band-edge photoluminescence shifts with changing band-gap energy to remain just below the excitonic luminescence for all compositions of CsPb(Cl 1−x Br x ) 3 (0 ≤ x ≤ 1). Computations show that this shift stems from the effect of the changing lattice dielectric constants on a shallow defect-bound exciton. Microscopic descriptions of this dopant-induced near-band-edge state and its relation to quantum cutting in Yb 3+ -doped CsPb(Cl 1−x Br x ) 3 are discussed.

Metal-halide perovskite (MHP) thin films show promise for integration into optoelectronic and spin-based devices. Here, we investigate spin dephasing in vapor-deposited CsPbBr 3 thin films via a combination of time-resolved Faraday rotation and magnetic circular dichroism spectroscopy. We observe coherent precession of both photogenerated electron and hole spins. For photogenerated holes, spin-dephasing times (T 2 *) can be elongated at cryogenic temperatures from 282 to 320 ps by application of a small magnetic field, which partially suppresses hyperfine dephasing. At elevated temperatures, hole-spin dephasing is accelerated by thermally excited longitudinal-optical phonons, but coherent hole-spin precession is still measurable at room temperature. Photogenerated electrons show rapid spin dephasing (∼40 ps) even at cryogenic temperatures. These results highlight that vapor-deposited CsPbBr 3 thin films offer a compelling platform for harnessing spins in MHP semiconductors, and their scalable manufacturing offers an attractive pathway to future device integration.

Point defects or impurities are either naturally present in semiconductors or may be intentionally introduced to tune their electronic and optical properties. The nature of impurity energy levels can strongly influence the performance of a semiconductor in applications ranging from solar cells to photodiodes to infrared sensors to qubits for quantum computing. In this work, we develop a framework powered by machine learning (ML) and high-throughput density functional theory (DFT) computations for the prediction and screening of functional impurities in group IV, III-V, and II-VI zinc blende semiconductors. Elements spanning the length and breadth of the periodic table are considered as impurity atoms at the cation, anion, or interstitial sites in supercells of 34 candidate semiconductors, leading to a chemical space of   12,000 points, 10% of which are used to generate a DFT dataset of charge dependent defect formation energies. Descriptors based on tabulated elemental properties, defect coordination environment, and relevant semiconductor properties are used to train ML regression models for the DFT computed properties, resulting in statistical predictions of the neutral state formation energies and charge transition levels of all possible impurities in the given set of compounds. Kernel ridge regression, Gaussian process regression, and neural networks, with appropriate feature selection and hyperparameter optimization, are seen to yield similar predictive performances and meaningful uncertainty estimates. We apply the ML framework to screen all impurities with lower formation energy than dominant native defects in all group IV, III-V, and II-VI zinc blende semiconductors. An online tool resulting from this work for predicting and visualizing defect properties in semiconductors is made available on github.