Persistent Spin Texture in Non-centrosymmetric 2D Perovskites through Rational Design

2D lead halide perovskites (LHPs) are promising semiconductor materials for spin-orbitronic applications. While the heavy atoms (Pb, I) in LHPs give rise to strong spin-orbit coupling (SOC), the organic cations can be used to template the perovskite structure and break inversion symmetry to produce Rashba and Dresselhaus spin splitting effects. However, the interaction between the organic cations and inorganic network can be complex and difficult to rationally tune. Here we introduce a design strategy to produce polar (C_2v) 2D lead iodide perovskites by selecting appropriate spacer cations, A-site cations, and quantum well thickness (n). We confirm structural non-centrosymmetry using single crystal X-ray diffraction and multidimensional second harmonic generation measurements. Ferroelectric properties are confirmed by the switchable photovoltaic effect and PE hysteresis measurements. Band structure calculations show Rashba and Dresselhaus splitting and unidirectional spin texture in k-space (i.e., persistent spin texture), which could lead to decreased Dykanov-Perel scattering and increased spin lifetimes. These results suggest 2D LHPs exhibiting cofunctional ferroelectricity and persistent spin texture can be rationally designed using these principles.