Broadband nonlinear absorption of two-dimensional PdX (X=S, Se, Te) nanosheets

In the fields of electrical and optical sciences, transition metal chalcogenides (TMCs) such as PdS, PdSe 2 and PdTe 2 have attracted significant attention due to their unique properties. But there are fewer reports on their nonlinear absorption (NLA) properties. In this study, two-dimensional (2D) PdS, PdSe 2 , and PdTe 2 nanosheets were synthesized via the liquid-phase exfoliation (LPE) method. Their broadband NLA responses were systematically investigated using the open-aperture (OA) Z-scan technique. The results revealed that the 2D PdS, PdSe 2 and PdTe 2 nanosheets exhibited pronounced two-photon absorption (TPA) properties from the ultraviolet (UV) to infrared (IR) band. The 2D PdS nanosheets exhibited the strongest TPA properties at the UV band. This superior performance is attributed to its highly symmetric layered structure, weaker spin-orbit coupling (SOC) effect, and lower defect density, which collectively enhance TPA properties. In contrast, PdSe 2 and PdTe 2 show progressively reduced TPA responses. Our results demonstrate that 2D PdS, PdSe 2 and PdTe 2 nanosheets possess significant potential as advanced optical limiting (OL) materials.