Enhancing the chiroptical response of displaced overlapping perovskite metamaterials via compositional asymmetry

Perovskite chiral metamaterials have shown great potential in applications such as circularly polarized light manipulation, information encryption, and biosensing. However, further enhancing their chiral optical performance remains a considerable challenge. Here, we propose a design strategy based on compositional asymmetry, introducing a MAPbI3/MAPbBr3 heterostructure into the two-wing architecture of a three-dimensional displaced perovskite metamaterial. This approach combines intrinsic material asymmetry with geometric asymmetry, enabling a synergistic enhancement of multiple chiral mechanisms. Experimental results reveal a notable circular dichroism (CD) response at 790 nm, with a peak absolute value of 21680 mdeg and an anisotropy factor (g-factor) as high as 1.37, significantly surpassing that of the homostructure control group. Further investigations demonstrate that adjusting the material composition of the heterostructure allows effective modulation of the peak wavelength and intensity of the CD signal at a fixed incident angle. This work provides a new pathway for tailoring chiroptical properties through chemical composition and broadens the application prospects of perovskite chiral metamaterials in multi-band circular polarization detection and encrypted optical devices.