Black phosphorus quantum dots.

As a unique two-dimensional nanomaterial, layered black phosphorus (BP) nanosheets have shown promising applications in electronics. Although mechanical exfoliation was successfully used to prepare BP nanosheets, it is still a challenge to produce novel BP nanostructures in high yield. A facile top-down approach for preparation of black phosphorus quantum dots (BPQDs) in solution is presented. The obtained BPQDs have a lateral size of 4.9±1.6 nm and thickness of 1.9±0.9 nm (ca. 4±2 layers). As a proof-of-concept application, by using BPQDs mixed with polyvinylpyrrolidone as the active layer, a flexible memory device was successfully fabricated that exhibits a nonvolatile rewritable memory effect with a high ON/OFF current ratio and good stability.