Achiral phosphonium induced remarkable circular polarized luminescence in a chiral cadmium(ii) halide perovskite material

Abstract

Circular polarized luminescence (CPL) sensitive two-dimensional organic inorganic halide perovskites have versatile applications in optical displays, encrypted transmission and quantum communications. Here, a new chiral hybrid [MePh₃P]₂CdCl₄ (PCC) single crystal (SC) is synthesized using an achiral phosphonium cation by a solvent evaporation process at room temperature (rt). SC x-ray study reveals a non-centrosymmetric point group 23, with 2₁-screw optical axes providing a chiral Sohncke space group. Hirshfeld surface analysis suggests long-range H-bonding and ionic interactions (~ 3–9 kJ mol⁻¹) and short-range Van der Waals and dispersion interactions (∼0.4–4 kJ mol⁻¹). Both the PCC thin films and SCs exhibit prominent circular dichroism (CD) and remarkably superior CPL activity at rt (|g_CD| ≈ 5 × 10⁻³ and |g_lum| ≈ 4.3 × 10⁻²).