Enhanced electroluminescence properties of doped ZnS nanorods formed by the self-assembly of colloidal nanocrystals

Aggregation based meso-scale self-assembly of doped semiconductor nanocrystals leading to the formation of monocrystalline nanorods showing enhanced photo- and electro-luminescence properties is reported. similar to 4 nm sized, polycrystalline ZnS nanoparticles of zinc-blende (cubic) structure, doped with Cu+-Al3+ have been aggregated in the aqueous solution and grown into nanorods of length similar to 400 nm and aspect ratio similar to 12. Transmission electron microscopic (TEM) images indicate crystal growth mechanisms involving particle-to-particle oriented-attachment assisted by sulphur-sulphur catenation leading to covalent-linkage. The nanorods exhibit self-assembly dependant luminescence properties such as quenching of the lattice defect-related emissions accompanied by the enhancement in the dopant-related emission, efficient low-voltage electroluminescence (EL) and super-linear voltage-brightness EL characteristics. This study demonstrates the technological importance of aggregation based self-assembly in doped semiconductor nanosystems. (c) 2005 Elsevier Ltd. All rights reserved.