Nonlinear optical properties and photoexcited carrier dynamics of MnPS nanosheets.

Here, we systematically report on the preparation of high-quality few-layered MnPS nanosheets (NSs) by chemical vapor transport (CVT) and mechanical stripping method, and its carrier dynamics and third-order nonlinear optical properties were studied. Using the classical technique of open aperture Z-scan, a typical phenomenon of saturable absorption (SA) was observed at 475 nm, which indicates that the material is expected to be used as a saturable absorber in ultrafast lasers. The typical phenomenon of reverse saturation absorption (RSA) is observed at 800 and 1550 nm, which shows its potential in the field of broadband optical limiting. Compared with graphene, BP, MXene, MoS and other typical two-dimensional materials, MnPS NSs has a higher modulation depth. Using the non-degenerate transient absorption spectroscopy technology at room temperature, a slower cooling process of thermal carrier of MnPS was observed. Moreover, the carrier lifetime can be tuned according to the wavelength. This work is of great significance to the improvement of MnPS based devices, and lays a foundation for the application of MnPS in short-wavelength photovoltaic cell, photoelectric detection and other fields.