CdS nanocrystals from a quaternary water-in-oil microemulsion: preparation and charcterization of self-assembled layers

High crystalline CdS nanocrystals, prepared by means of an improved synthetic route that exploits a quaternary water-in-oil microemulsion are immobilised on gold and quartz substrates by Self-Assembly. The obtained nanocrystals and layers are characterised by Scanning Tunnelling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD) and UV-vis spectroscopy. The results evidence that the CdS nanocrystals show a good adherence to the substrate, are quite stable in air for months, and still retain their size and quantum properties after immobilisation. The data are discussed in terms of the increased stability of the nanocrystals in solution due to the presence of the co-surfactant that acts as capping agent.