Circularly Polarized Luminescence in Achiral Tin-Based Perovskites via Structural Isomer-Driven Coordination Interaction

Abstract

A chiral bidentate ligand, (R)-(−)-1-amino-2-propanol (denoted as R₁) or (R)-(−)-2-amino-1-propanol (denoted as R₂), was used to modify achiral 2D tin-based perovskite HDASnBr₄ (HDA: 1,6-hexamethylenediamine) to form R₁-HDASnBr₄ or R₂-HDASnBr₄ by an acid precipitation method. R₁-HDASnBr₄ exhibits a near-unity photoluminescence quantum yield (PLQY) and strong yellow circularly polarized luminescence (CPL) with a luminescence asymmetry g-factor (|g_lum|) of 8.3 × 10^–3, while R₂-HDASnBr₄ shows a PLQY of 95% and |g_lum| of 3.2 × 10^–3. Both exhibit strong CPL activities, attributed to the significant centro-asymmetric distortion induced by the interaction between the chiral ligand and the inorganic lattice of 2D perovskites. The |g_lum| of R_1-HDASnBr₄ is 2.6× that of R₂-HDASnBr₄, resulting from the direct coordination of the hydroxyl group attached to the chiral carbons in R₁ with the [SnBr₆]^4– inorganic framework, which induces a higher degree of distortion than the amino group in R₂. Furthermore, we explored the potential of R₁-HDASnBr₄ as a chiral inducer and a CPL source to facilitate asymmetric polymerization. This work offers a simple strategy to introduce chirality to achiral perovskites.