Insight from theory on optoelectronic properties of layered hybrid perovskites
Résumé
Solution-processed organometallic halide perovskite have recently emerged as promising absorbers in the realm of photovoltaic technology. During the first years of this “perovskite boom”, attention has been drawn on 3D structural networks with methylammonium lead iodide as the superstar. More recently, layered hybrid perovskites gained renewed interest for several reasons, among which increased stability and room for chemical design as well as broader perspectives for technological advances. In the last few months, several families of phase-pure n-layered perovskites (n number of octahedron in the perovskite layer sandwiched between two organic layers) have been synthetized and shown to demonstrate key features promising for both fundamental physics and improved devices. Here, starting from our early theoretical contribution on a 1-layered lead-halide perovskite, which has highlighted differences with conventional semiconductors and importance of relativistic effects, we will investigate through a couple of examples quantum and dielectric confinement, excitons in bulk5 and their fate on the surface as well as the composite nature of this class of semiconductors that facilitates the determination of band alignments and offers a framework suited to provide design principles for next generation technologies. The theoretical modeling capitalizes on available DFT codes, development of DFT-based methodologies including empirical resolution of the Bethe-Salpeter Equation that leads to quantitative agreement with exciton binding energies as determined by low-temperature high-field magneto-absorption experiments.