Unambiguous Bulk Circular Photogalvanic Effect Enabled by Symmetry-Selective Excitation in Two-Dimensional Hybrid...

The circular photogalvanic effect (CPGE) enables helicity-dependent photocurrent generation in noncentrosymmetric materials, probing spin-polarized electronic states. However, CPGE signals are often obscured by interfacial symmetry breaking, complicating the identification of intrinsic bulk responses. Here, we demonstrate the unambiguous observation of CPGE originating purely from intrinsic bulk polarity in two-dimensional organic-inorganic hybrid perovskites (2D-OIHPs). By employing normal-incidence circularly polarized light as a symmetry-selective excitation scheme, surface contributions are suppressed within the nanoscale photoactive region, enabling direct detection of bulk CPGE governed by inversion symmetry breaking. Using polar 2D-OIHP crystals incorporating dipolar organic cations, we observe helicity-dependent photocurrents determined by bulk polarity. Furthermore, the introduction of molecular chirality enables deterministic photocurrent reversal via chirality-coupled polarization switching between enantiomers. These results establish a general strategy for isolating and controlling bulk spin-dependent photo-responses while revealing a direct link between molecular design, bulk polarity, and spin-polarized photocurrent generation. Our findings highlight 2D-OIHPs as a versatile platform for symmetry-engineered opto-spintronic functionalities and helicity-sensitive photodetection.