Sizeable square CsPb 2 Br 5 nanosheets for photodetection.

All-inorganic perovskites have garnered significant attention in optoelectronics. Herein, square CsPb 2 Br 5 nanosheets, with lateral dimensions of up to 200 μm and a thickness of less than 50 nm, were successfully synthesized via a straightforward aqueous method using HBr as a morphology-tailoring agent. A photodetector composed of a single nanosheet was subsequently fabricated and exhibited remarkable photodetection capabilities, demonstrating a detectivity of 5.98 × 10 9 Jones. These findings offer new perspectives on the synthesis and utilization of CsPb 2 Br 5 and other perovskite nanostructures in optoelectronic devices.