Surfactant ligand removal and rational fabrication of inorganically connected quantum dots.
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.
Department of Materials Science and Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States.
Haitao
H
Zhang
Bo
B
Hu
Liangfeng
L
Sun
Robert
R
Hovden
Frank W
FW
Wise
David A
DA
Muller
Richard D
RD
Robinson