Strong Rashba‐Dresselhaus Effect in Nonchiral 2D Ruddlesden‐Popper Perovskites

Abstract Chirality transfer from organic chiral molecules to lead halides is theorized as the origin of the strong Rashba‐Dresselhaus effect causing large circular dichroism (CD) and circularly polarized luminescence (CPL) in metal halide perovskites (MHPs). Here, a concrete empirical evidence is provided that such strong CD and CPL can occur even in nonchiral 2D Ruddlesden‐Popper perovskites (RPPs) (BA)₂(MA)_n−1Pb_nI_3n+1 (where MA = CH₃NH₃ and BA = CH₃(CH₂)₃NH₃). The CD and CPL responses occurring at the excitonic transition of the MHPs are strongest (≈100 mdeg and 4.8%, respectively) when a single lead halide octahedral [PbI₆]⁴⁻ layer is repeatedly stacked between two nonchiral molecules BA⁺ (n = 1). However, they are rapidly quenched as n increases. It is hypothesized that strong Rashba‐Dresselhaus splitting in the 2D RPPs originates the strong CD and CPL signatures. Density functional theory calculations reveal that the large interlayer distortions in the inorganic layers at the organic/inorganic interface give rise to the strong Rashba‐Dresselhaus splitting. A Rashba‐Dresselhaus field of ≈600 and ≈50 mT for n = 1 and 2, respectively, is estimated by magnetic circular dichroism spectroscopy. The studies may have significant impact on designing 2D RPPs with large Rashba‐Dresselhaus effects at room temperature for spintronic applications.