Novel hybrid materials of cellulose fibres and doped ZnS nanocrystals

During the past decade semiconductor nanocrystals have been studied extensively, in particular ZnS nanocrystals doped with optically active luminescent centres. Such materials have created new opportunities in the areas of photo-voltaic solar cells and light-emitting diodes. In this study, photoluminescent cellulose fibres were prepared by coating bleached Kraft fibres (Pinus radiata) with ZnS nanocrystals doped with Mn2+ and Cu2+ ions. In doing so, the inherent properties of the fibre (such as tensile strength and flexibility) have been preserved, but imparted to it are the photoluminescent properties of the coating. A wet chemical synthesis method was used in which homogenous solutions of zinc salts and transition metal salts were precipitated with sodium sulfide. Dopant concentrations ranged from 0.1 to 2 wt%. After successive washings and sonication, the particles remained bonded to the surface of the fibre, and the fibres were able to be formed into a paper sheet. Samples were characterized by photoluminescence spectroscopy, scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and X-ray photoelectron spectroscopy.