Advances and Promises of Layered Halide Hybrid Perovskite Semiconductors

Abstract

Layered halide hybrid organic-inorganic perovskites (HOP) have been the subject of intense investigation before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells and revisited for light-emitting devices. In this review, we combine classical solid-state physics concepts with simulation tools based on density functional theory to overview the main features of the optoelectronic properties of layered HOP. A detailed comparison between layered and 3D HOP is performed to highlight differences and similarities. In the same way as the cubic phase was established for 3D HOP, here we introduce the tetragonal phase with D symmetry as the reference phase for 2D monolayered HOP. It allows for detailed analysis of the spin-orbit coupling effects and structural transitions with corresponding electronic band folding. We further investigate the effects of octahedral tilting on the band gap, loss of inversion symmetry and possible Rashba effect, quantum confinement, and dielectric confinement related to the organic barrier, up to excitonic properties. Altogether, this paper aims to provide an interpretive and predictive framework for 3D and 2D layered HOP optoelectronic properties.

Rashba and Dresselhaus Couplings in Halide Perovskites: Accomplishments and Opportunities for Spintronics and Spin–Orbitronics

“…7,62,63 Indeed, these systems are, in many ways, very similar to the heterostructures in which the Rashba and Dresselhaus effects are commonly found.…”

“…Indeed, several compounds belong to polar groups and have been scrutinized. 7,29,56,64,65 One should notice that the above examples have a symmetry axis perpendicular to the staking direction. As a consequence, the Rashba effect is incomplete, i.e.…”

“…3,4 Opting for various mixtures of halide and cations, 2 various forms, e.g. layered HOP, [5][6][7] or by encapsulating the materials, the stability went from few hours to several thousands hours. Encouraged by these breakthroughs, a third path has pushed the area of hight performance solar cells from less than 1 cm 2 up to 50 cm 2 with a PCE of 12.6%, 8 bringing the perovskite solar cells even closer to commercial use.…”

“…7,[24][25][26][27]29,30,58 The computational approach, whether it relies on density functional theory (DFT) with or without hybrid functionals, 29,59 GW approximation, 60 or semi-empirical modeling (e.g. k · p or tight-binding), constitutes a precious tool, combined with symmetry analysis, in the characterization of SOC-induced spin splittings.…”

Scaling law for excitons in 2D perovskite quantum wells

“…Moreover, unlike bulk inorganic semiconductors, heterostructures 17 and 3D perovskites 18,19 , it is non-trivial to determine the exciton reduced mass in layered hybrid perovskites using a symmetry-based ( k.p ) approach 20 or using many-body ab initio calculations 21 . Furthermore, ambiguity in the determination of the exciton binding energy in layered 2D perovskites has also been imposed by the limited understanding of the role of dielectric confinement versus quantum confinement with increasing quantum well thickness 22,23 . More generally, phase-pure RPPs with n greater than 1 present a unique opportunity to explore the physical properties of natural quantum well semiconducting crystals intermediate between monolayer 2D materials 24,25 and 3D materials 26 , a quasi-dimensional physics only accessible in synthetic inorganic semiconductor quantum well structures so far 26 .…”