Layered Cs3Bi2I9 perovskite nanosheets on TiO2 nanorods for high-performance heterostructure photodetectors†

In this study, we report the fabrication of two-dimensional (2D) Cs₃Bi₂I₉ halide perovskite semiconductor photodetectors with enhanced photostability against temperature. These all-inorganic layered Cs₃Bi₂I₉ nanosheet-based photodetectors exhibit enhanced photoresponse. We deposited Cs₃Bi₂I₉ hexagonal-shaped perovskite nanosheets onto TiO₂ nanorods (NRs) using a chemical vapour deposition technique (CVD). The combination of Cs₃Bi₂I₉ nanosheets with TiO₂ nanorods (NRs) creates a hybrid heterostructure that facilitates efficient extraction of photo-generated charge carriers, leading to a strong photocurrent with a broad spectral response from UV to visible light. The 2D layer structure of the perovskite effectively extracts the photo-excited charge carriers, which in turn generates a high photocurrent. The photodetectors exhibit high responsivity (1.1 A W⁻¹) within the visible spectral range of 450–750 nm and an even higher specific detectivity of 1.969 × 10¹¹ Jones at a 2 V applied bias. These results highlight the promise of high-performance inorganic layered Cs₃Bi₂I₉ photodetectors for future optoelectronic sensors and logic gates.