A reduced-dimensional polar hybrid perovskite for self-powered broad-spectrum photodetection

Polar hybrid perovskites have been explored for self-powered photodetection benefitting from prominent transport of photo-induced carriers and the bulk photovoltaic effect (BPVE). However, these self-powered photodetection ranges are relatively narrow depending on their intrinsic wide bandgaps (>2.08 eV), and the realization of broad-spectrum self-powered photodetection is still a difficult task. Herein, we successfully obtained a polar multilayered perovskite, (I-BA)₂(MA)₂Pb₃I₁₀ (IMP, MA⁺ = methylammonium and I-BA⁺ = 4-iodobutylammonium), via rational dimension reduction of CH₃NH₃PbI₃. It features the narrowest bandgap of 1.71 eV in a BPV material. As a consequence, the integration of narrow bandgap and BPVE causes the self-powered photodetection to extend to 724 nm for IMP, and a repeatable photovoltaic current reaching 1.0 μA cm^-2 is acquired with a high "on/off" ratio of ∼10³ and photodetectivity (∼10⁹ Jones) at zero bias. This innovative research provides a foothold for adjusting the physical properties of hybrid perovskites and will expand their potential for self-powered broad-spectrum detection.