et al.. Bright-exciton splittings in inorganic cesium lead halide perovskite nanocrystals. AbstractSince their …rst synthesis in 2015, the all-inorganic lead halide perovskite nanocrystals CsPbX 3 (X = Cl, Br, I) have attracted a great attention due to their outstanding electronic and optical properties as well as their performances which outclass the ones of II-VI conterparts in many application …elds. In addition to these properties, the understanding of the emission features in these systems at the single object scale is crucial e.g. for nanophotonics and quantum optics devices. The details of the band-edge excitonic emission are here theoretically explored. The contribution of the long-range exchange interaction to the bright-exciton splittings is computed in strong and weak con…nement regimes by using the group theory and k.p arguments. We show that the shape anisotropy of a nanocrystal can also be at play with the crystalline (cubic, tetragonal or orthorhombic) structures to explain the emission properties. In the weak con…nement regime, splittings are inversely proportional to the cube of the exciton Bohr radius and we observe an increase of the splittings from iodide, to bromide, then chloride perovskite compounds. However, in the strong con…nement regime, splittings increase inversely proportional to the nanocrystal volume and, for a given nanocrystal size, the splitting values are comparable for the three halide perovskite materials. The present theoretical developments lead to quantitative contributions in good agreement with available experimental data mainly in the weak con…nement regime.

A 40-band k⋅p model is used to compute the standard k⋅p band parameters at Γ, X, and L valleys in direct-band-gap bulk materials for Td group semiconductors. The values of the effective masses for electrons, heavy holes, and light holes in the Γ, X, and L valleys are in good agreement with those reported in other publications. Satisfactory agreement with available experimental data is also obtained by the present model. Finally, our results show that the effective Landé factor g∗, the κ valence band parameter, and the Dresselhauss spin-orbit coupling constant δ conicide well with available experimental data. The k⋅p Hamiltonian parameters, in particular, are adjusted to get g∗(GaAs)=−0.42, which turn out to be in agreement with the experimental value of −0.44.

The band structure of indirect-band gap semiconductors ͑AlAs, GaP͒ as well as indirect-band gap alloys semiconductors ͑GeSi͒ is described theoretically by using a 30ϫ 30 k ϫ p model including the d far-level contribution. For all materials investigated, the resulting electronic band structure parameters are in good agreement with experimental values. The method also provides a good description of the second conduction band which is useful for transport modeling. Finally, our results show that Luttinger parameters, the valence band parameter, and the effective masses in the X and L valleys are in good agreement with available experimental data.

We synthesized strongly anisotropic CsPbBr3 nanocrystals with very narrow emission and absorption lines associated to confinement effects along one or two dimensions, called respectively nanoplatelets (NPLs) and nanosticks (NSTs). Transmission...