On-Wire Design of Axial Periodic Halide Perovskite Superlattices for High-Performance Photodetection

Precise synthesis of all-inorganic lead halide perovskite nanowire heterostructures and superlattices with designable modulation of chemical compositions is essential for tailoring their optoelectronic properties. Nevertheless, controllable synthesis of perovskite nanostructure heterostructures remains challenging and underexplored to date. Here, we report a rational strategy for wafer-scale synthesis of one-dimensional periodic CsPbCl₃/CsPbI₃ superlattices. We show that the highly parallel array of halide perovskite nanowires can be prepared roughly as horizontally guided growth on an M-plane sapphire. A periodic patterning of the sapphire substrate enables position-selective ion exchange to obtain highly periodic CsPbCl₃/CsPbI₃ nanowire superlattices. This patterning is further confirmed by micro-photoluminescence investigations, which show that two separate band-edge emission peaks appear at the interface of a CsPbCl₃/CsPbI₃ heterojunction. Additionally, compared with the pure CsPbCl₃ nanowires, photodetectors fabricated using these periodic heterostructure nanowires exhibit superior photoelectric performance, namely, high I_ON/I_OFF ratio (10⁴), higher responsivity (49 A/W), and higher detectivity (1.51 × 10¹³ Jones). Moreover, a spatially resolved visible image sensor based on periodic nanowire superlattices is demonstrated with good imaging capability, suggesting promising application prospects in future photoelectronic imaging systems. All these results based on the periodic CsPbCl₃/CsPbI₃ nanowire superlattices provides an attractive material platform for integrated perovskite devices and circuits.