A strategy of chiral cation coordination to achieve a large luminescence dissymmetry factor in 1D hybrid manganese halides

Abstract

Chiral organic–inorganic metal halides (OIMHs) have emerged as a new class of promising circularly polarized luminescence (CPL) materials owing to their structural tunability and fascinating optoelectronic properties. However, the development of high-performance chiral hybrid OIMHs remains a critical challenge, largely attributed to the absence of effective strategies for modulating chiroptical activity. Herein, we present enantiomeric hybrid manganese bromides, denoted as R/S-DACAMnBr₃, featuring a one-dimensional chain structure alternately coordinated by organic cations via edge-sharing MnOBr₅ octahedra, which establishes a robust chiral transfer pathway from organic cations to inorganic emissive centers. This structural design synergizes with the high intrinsic emission efficiency of Mn²⁺ centers to achieve intense orange CPL at 626 nm, yielding a remarkable luminescence dissymmetry factor (g_lum) of 0.292 for S-DACAMnBr₃, which surpasses most reported chiral OIHMs by 1–3 orders of magnitude. Remarkably, a positive magneto-chiroptical effect under a 1.6 T magnetic field amplifies the g_lum value to 0.321 at room temperature, demonstrating the first example of magnetic-field-enhanced CPL in lead-free OIMHs. The practical viability is further evidenced by S-DACAMnBr₃-based circularly polarized light-emitting diodes exhibiting a strong CPL signal at 620 nm with a g_lum of 6.4 × 10⁻³, alongside single-crystal photodetectors achieving a switching ratio of 7.72. These findings contribute valuable insights for amplifying the chiroptical activity of hybrid OIMHs via a strategy of chiral cation coordination, which may pave the way for the development of effective CPL materials toward diverse applications in the future.