Impact of Structural Distortions on the Optoelectronic and Spin-Related Properties of Two-Dimensional Hybrid Perovskites
In summary, an interplay of charge-density (electrostatic) requirements, steric factors, and hydrogen bonding interactions induces detailed structural distortions in 2D perovskites, the nature and degree of which are specific to the cation and inorganic framework in question. Yet, the general influence of a cation on the structural aspects of perovskite layers can be rationalized, based on the discussion of several examples presented here. The structural distortions discussed are closely connected with key material properties such as bandgap, optical emission, and spin characteristics. By lowering the lattice symmetry, structural distortions decrease the band dispersions and thereby increase the bandgaps. Distortions increase the propensity toward carrier/exciton self-trapping, as well as defect-formation, leading to broadband emission characteristics of considerable interest in lighting applications. When inversion symmetry is broken by such distortions, novel condensed matter phenomena such as RD effects can be induced, opening new avenues in the realm of hybrid perovskite spintronics. Nonlinear light-matter interactions, as well as ferroelectricity, can also arise from inversion asymmetry. We expect more structure–property relationships to be uncovered in the future, with the underpinning tailorable structural distortions serving as a knob to control the charge-, light- and spin-related properties of 2D perovskites for their potential application in the areas of energy, optoelectronics, and spintronics.
