We examine the dependence on size distribution of the Raman line shape of optical vibron modes in CdSe dots. A detailed comparison with the theory of electron-hole correlated Raman scattering in spherical quantum dots, which includes LO-confined modes, is carried out. The obtained CdSe vibron frequencies are found to map well on the ab initio calculated LO phonon dispersion relations of wurtzite CdSe along the ͓001͔ direction of the Brillouin zone.

The electronic structure and properties of the orthorhombic phase of the CH 3 NH 3 PbI 3 perovskite are computed with density functional theory. The structure, optimized using a van der Waals functional, reproduces closely the unit cell volume. The experimental band gap is reproduced accurately by combining spin-orbit effects and a hybrid functional in which the fraction of exact exchange is tuned self-consistently to the optical dielectric constant. Including spin-orbit coupling strongly reduces the anisotropy of the effective mass tensor, predicting a low electron effective mass in all crystal directions. The computed binding energy of the unrelaxed exciton agrees with experimental data, and the values found imply a fast exciton dissociation at ambient temperature. Also polaron masses for the separated carriers are estimated. The values of all these parameters agree with recent indications that fast dynamics and large carrier diffusion lengths are key in the high photovoltaic efficiencies shown by these materials.

Antimony and bismuth ⟨111⟩ layered perovskites have recently attracted significant attention as possible, nontoxic alternatives to lead halide perovskites. Unlike lead halide perovskites, however, ⟨111⟩ halide perovskites have shown limited ability to tune their optical and electronic properties. Herein, we report on the metal alloying of manganese and copper into the family of materials with formula Cs 4 Mn 1−x Cu x Sb 2 Cl 12 (x = 0−1). By changing the concentration of manganese and copper, we show the ability to modulate the bandgap of this family of compounds over the span of 2 electron volts, from 3.0 to 1.0 eV. Furthermore, we show that in doing so, we can also adjust other relevant properties such as their magnetic behavior and their electronic structure.

Akin to the expansion in compositional diversity that halide double perovskites provided to three-dimensional perovskites, layered double perovskites could further expand the diversity of two-dimensional (2D) perovskites, and therefore, they could also enhance the properties or expand the possible applications of such materials. Despite the great promise of halide 2D double perovskites, up to date, there are only four confirmed members of this family of materials. Herein, we explore 90 hypothetical new members of this family of materials by a combined theoretical, computational, and experimental method. The combination of these tactics allowed us to predict several new materials, out of which we experimentally synthesized and characterized five new layered double perovskites, some of which show promising properties for their use in photovoltaics and optoelectronics. Further, our work highlights the vast diversity of compositions and therefore of applications that double-layered perovskites have yet to offer.