Inter-Phase Chirality Transfer in 2D and Quasi-2D Perovskite Heterostructures

Two-dimensional (2D) chiral metal halide perovskites (CMHPs) emerged as promising materials for spintronics. These 2D semiconductors comprise single layers of corner-sharing metal halide octahedra (n = 1) intercalated by organic cations, which limits charge mobility and spin lifetime. In comparison, quasi-2D analogs, with two or more octahedra layers (n ≥ 2), exhibit higher charge carriers mobility, augmented spin lifetime, and tailorable bandgap. Nonetheless, the few reports on quasi-2D CMHPs in the literature often describe time-consuming synthesis and materials presenting poor chiroptical properties after processing. We address this limitation by designing heterostructure thin films comprising a chiral n = 1 phase with a non-chiral n = 2 phase. Circular dichroism (CD) manifestation in the non-chiral phase confirms chirality transfer in the heterostructures. We found that chirality transfer depends on the intermolecular interaction of the chiral and non-chiral cations, being effective when R-/S-𝛼-methylbenzylammonium (MBA) in the chiral phase is combined with benzylammonium (BZA) in the non-chiral phase. Chirality transfer is weak when n-butylammonium (BA) is used in the non-chiral phase. We attribute this difference to a more effective intermixing enabled by 𝜋-𝜋 stacking in the MBA/BZA heterostructure. This inter-phase chirality transfer strategy opens a new avenue for spintronic materials design.