Growth of nanocrystals and thin films at the water—oil interface

The use of the water—oil interface provides significant advantages in the synthesis of inorganic nanostructures. Employing the water—toluene interface, luminescent CdS nanocrystals have been obtained at a relatively modest temperature of 35°C. The diameters of the particulates can be varied between 1.0 and 5.0 nm. In addition, we have devised a new method for transferring thin films at the water—toluene interface onto solid substrates. Using this method, thin films consisting of Au and Ag nanocrystals spread over very large areas (square centimetres) are obtained in a single step. These films are directly usable as ingredients of functional devices. We show this by constructing a working amine sensor based on films of Au nanocrystals. The materials obtained have been characterized by X-ray diffraction, scanning and transmission electron microscopy, absorption and emission spectroscopy and charge transport measurements.