Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots

http://dx.doi.org/10.1021/nl202892p

A novel method is reported to create inorganically connected nanocrystal (NC) assemblies for both II–VI and IV–VI semiconductors by removing surfactant ligands using (NH₄)₂S. This surface modification process differs from ligand exchange methods in that no new surfactant ligands are introduced and the post-treated NC surfaces are nearly bare. The detailed mechanism study shows that the high reactivity between (NH₄)₂S and metal–surfactant ligand complexes enables the complete removal of surfactant ligands in seconds and converts the NC metal-rich shells into metal sulfides. The post-treated NCs are connected through metal–sulfide bonding and form a larger NCs film assembly, while still maintaining quantum confinement. Such “connected but confined” NC assemblies are promising new materials for electronic and optoelectronic devices.

DOI: 10.1021/nl202892p

Publication Date (Web): October 19, 2011