Dr. Mikaël Kepenekian - Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes - CNRS, France

3D hybrid organic-inorganic perovskites have become extremely popular over the last three years in the field of photovoltaics. In addition to its impressive efficiencies records in the solar-to-electricity conversion, they exhibit a large range of possible structures and over the past thirty years, these materials were more intensively studied in their 2D form, for applications in optoelectronics and microelectronics. Recently, 0D perovskite-based nano-objects, such as colloidal nanoplatelets, have also attracted attention from the scientific community. Importantly, the ability to modify the dimensionality and shape of objects allows one to tune effect of quantum and dielectric confinements. These effects are of prime importance for photovoltaic and optoelectronic applications. All those materials have also shown attractive spin-related properties.

We use symmetry analysis, density functional calculations and model Hamiltonians to scrutinize the dielectric confinements effects as well as Rashba and Dresselhaus effects in hybrid organic-inorganic halide perovskites. Based on our original ab initio approach, we inspect herein confinement effects in nanoplatelets of allinorganic and hybrid perovskites. In addition to size and dimensionality effects, we survey the influence of the cation (inorganic vs. organic) and of the halide (I, Br, Cl). Moreover, we rationalize the importance of ionic contributions (polar phonons) to the dielectric constants thanks to computation of both static and high frequency dielectric properties. The importance of dielectric confinement effects in colloidal nanostructures of halide perovskites is described for the first time in this contribution.

With a detailed study of the electronic structures of a variety of system as well as the symmetries we detail the origin of the spin splitting in two- and three-dimensional hybrid perovskites. Finally, we show that layered structures of CH3NH3PbX3 (X=I, Br) leads to a splitting that can be controlled by an applied electric field. From these observations we propose a setup for a spin-FET, opening the door to a perovskite-based spintronics.2