Construction of chiral-2D/3D perovskite heterojunction films for efficient circularly polarized light detection

2D Ruddlesden-Popper perovskites with chiral organic ligands are emerging as promising candidates for circularly polarized light (CPL) detection, which has important applications in quantum communication and opto-spintronics. However, the insulating organic spacers in 2D perovskites generally hinder carrier transport and charge extraction, hence leading to a low responsivity of photodetectors. Herein, we have prepared a chiral-2D/3D perovskite heterojunction thin film via intermittent spin-coating of the chiral-2D ligands on top of a 3D perovskite film. The chiral-2D perovskite formed on top of the film functions as the CPL absorption layer, while the energy transfer between chiral-2D and 3D perovskites and the dissociation of excitons in the 3D phase facilitate the efficient lateral carrier transport and extraction in the bottom 3D perovskite-based charge transport channel. The resultant heterojunction CPL detectors exhibit a high anisotropy factor of 0.13 and a large specific detectivity of above 6.8 x 1010 Jones that significantly outperform those of the pure chiral-2D based ones, which paves the way for the design and preparation of high performance perovskite thin film-based CPL detectors. A chiral-2D/3D perovskite heterojunction is prepared via intermittent spin-coating of the chiral-2D ligands on top of a 3D perovskite film, which shows enhanced circularly polarized light detection performance as compared to the chiral-2D based ones.