Cs3Sb2Br9: A lead-free perovskite quantum dots as optical limiting material with favourable optical limiting threshold and nonlinear optical properties

In recent years, optical limiting (OL) materials based on nonlinear optical effects have been widely used in military, optical engineering and scientific research fields. Pb-based perovskite quantum dots (QDs) materials are regarded as potential OL materials due to its excellent linear and nonlinear optical properties, resulting from the lone pair orbital 6s2 of Pb. However, the larger OL threshold and toxicity of Pb limit its wider applications. Herein, Cs3Sb2Br9 QDs were synthesized by supersaturated crystallization method, in which Sb has the same solitary pair orbit as Pb. The nonlinear optical absorption (NLA) and OL characteristics are studied by using the open-hole Z-scan technique under the irradiation of 532 nm laser. The NLA coefficient is recorded as β = 62 cm GW−1, which is three orders of magnitude larger than CsPbBr3 nanocrystals (NCs), and the OL threshold is derived as Fth = 2 J cm−2, which is better than other OL materials reported in the literatures, rooting in free carrier absorption (FCA) under different laser energies. In general, these results indicate that Cs3Sb2Br9 QDs can be a potential superior candidate as OL material for practical expansive applications.