Synthesis and nonlinear optical switching of Bi2S3 nanorods and enhancement in the NLO response of Bi2S3@Au nanorod-composites

Abstract

Organic solvent dispersible bismuth(III) sulfide (Bi2S3) nanorods were prepared by the chemical decomposition of tris(monothiobenzoato) bismuth(III), [Bi(SCOPh)3] as a single molecular precursor in the presence of trioctylphosphine oxide (TOPO) and 1-dodecanethiol (DdT). The rod surfaces of the as-prepared Bi2S3 nanorods were attached to Au nanoparticles (NPs) via direct reduction of KAuCl4·2H2O in the presence of octylamine (OTA) and oleic acid (OA). The attachment of the Au NPs onto the Bi2S3 rod surfaces was found to be relatively stable. The prepared samples (both Bi2S3 and Bi2S3@Au) were characterized by powder X-ray diffraction (PXRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) analysis and UV-vis spectroscopy. Their nonlinear-absorption (NLA) responses were studied using laser pulses at 532, 780 and 1064 nm, and the observed enhancement in the NLO response of Bi2S3@Au was discussed. Optical switching behaviour was observed at all the wavelengths.