Graphene-Templated Achiral Hybrid Perovskite for Circularly Polarized Light Sensing

Abstract

This study points out the importance of the templating effect in hybrid organic–inorganic perovskite semiconductors grown on graphene. By combining two achiral materials, we report the formation of a chiral composite heterostructure with electronic band splitting. The effect is observed through circularly polarized light emission and detection in a graphene/α–CH(NH₂)₂PbI₃ perovskite composite, at ambient temperature and without a magnetic field. We exploit the spin–charge conversion by introducing an unbalanced spin population through polarized light that gives rise to a spin photoconductive effect rationalized by Rashba-type coupling. The prepared composite heterostructure exhibits a circularly polarized photoluminescence anisotropy g_CPL of ∼0.35 at ∼2.54 × 10³ W cm^–2 confocal power density of 532 nm excitation. A carefully engineered interface between the graphene and the perovskite thin film enhances the Rashba field and generates the built-in electric field responsible for photocurrent, yielding a photoresponsivity of ∼10⁵ A W^–1 under ∼0.08 μW cm^–2 fluence of visible light photons. The maximum photocurrent anisotropy factor g_ph is ∼0.51 under ∼0.16 μW cm^–2 irradiance. The work sheds light on the photophysical properties of graphene/perovskite composite heterostructures, finding them to be a promising candidate for developing miniaturized spin-photonic devices.