Investigation of Halogen Substitution Effects in <i>π</i> ‐Conjugated Organic Ligands of Chiral Hybrid Perovskites on Their Chiroptical Activity

ABSTRACT This study investigates the impact of novel π ‐extended thiophene‐based ligands with varying halogen substitutions on the chiroptical and optoelectronic properties of chiral 2D hybrid organic‐inorganic perovskites (HOIPs). Thin‐film and structural analyses reveal that the chirality transfer from organic ligands to the inorganic perovskite framework is enhanced by larger halogen substituents, which increase NH 3 + penetration depth and hydrogen bonding strength, leading to significant lattice distortions. These distortions amplify circular dichroism (CD) and circularly polarized luminescence properties, achieving a higher g CD value compared to commonly used ligands such as methylbenzylamine (MBA). The fabricated photodetector devices demonstrate a low dark current and high circularly polarized light discrimination capability, confirming the role of tailored ligand design in improving chiral perovskite performance. This work underscores the potential of introducing heteroaromatic ligands for advancing next‐generation chiroptoelectronic applications.