Bismuth sulphide–polymer nanocomposites from a highly soluble bismuth xanthate precursor

Abstract

Bismuth sulphide nanocrystal–polymer hybrid layers are of interest for various optoelectronic, thermoelectric or sensing applications. In this work, we present a ligand-free in situ route for the formation of Bi₂S₃ nanorods directly within a polymer matrix. For this purpose, we introduce a novel bismuth xanthate (bismuth(III) O-3,3-dimethylbutan-2-yl dithiocarbonate), which is highly soluble in non-polar organic solvents. The analysis of the crystal structure revealed that the prepared bismuth xanthate crystallises in the monoclinic space group C2/c and forms dimers. The bismuth xanthate can be converted into nanocrystalline Bi₂S₃ with an orthorhombic crystal structure via a thermally induced solid state reaction at moderate temperatures below 200 °C. In combination with the high solubility in non-polar solvents this synthetic route for Bi₂S₃ is of particular interest for the preparation of Bi₂S₃–polymer nanocomposites as exemplarily investigated on Bi₂S₃–poly(methyl methacrylate) and Bi₂S₃–poly(3-hexylthiophene-2,5-diyl) (P3HT) nanocomposite layers. Atomic force and transmission electron microscopy revealed that Bi₂S₃ nanorods are dispersed in the polymer matrix. Photoluminescence experiments showed a quenching of the P3HT fluorescence with increasing Bi₂S₃ content in the hybrid layer.