Tailoring of nonlinear optical and optical limiting performance through morphology: PbTe nanostructures in liquid and solid-state matrice

Abstract

Advances in nanotechnology have provided opportunities to precisely control the morphology of nanostructures and the ability to explore their structure–property relationships. In this work, well-defined PbTe nanostructures with different morphologies were prepared by a one-step microwave synthesis process. The synthesized PbTe nanostructures were incorporated into solid-state silica gel glass matrices by a facile sol-gel approach for application as optical limiters. Nonlinear optical (NLO) and optical limiting (OL) properties were measured by 532-nm laser pulses with a pulse duration of 35 ps to understand the relationship between the NLO properties and the morphology of six PbTe nanostructures (i.e., nanosheets, nanorods, particle assemblies, hoppercubes, nanocubes, and nanoflowers). The PbTe nanostructures had notably different NLO and OL properties, which strongly correlated with the structural characteristics both in liquid and gel glass matrices. The NLO mechanism was also explored and attributed to excited state absorption, which relates to the size and morphology of the nanostructures. The PbTe particle assemblies had the strongest NLO response under laser irradiation, whereas the PbTe nanocubes had the weakest response, both in liquid and a solid-state gel glass matrices. Importantly, a large OL effect was observed for PbTe particle assemblies doped into silica gel glasses, where the OL threshold surpassed that of previously reported semiconductor nanocrystals. This result suggests these materials can be considered as potential candidate for practical applications in the fields of nonlinear optics. Our work provides insights into the morphology dependence of NLO properties and a strategy to optimize the performance of nanostructures through structural design.