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 (NH 4) 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 (NH 4) 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. © 2011 American Chemical Society.

Citation

Zhang H, Hu B, Sun L, Hovden R, Wise FW, et al. (2011) Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots. Nano Lett 11: 5356–5361. Available: http://dx.doi.org/10.1021/nl202892p.

Sponsors

We acknowledge helpful discussions with Professor Tobias Hanrath. This publication is based on work supported in part by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST) and by the Semiconductor Research Corporation and the Center for Nanoscale Systems (NSF #EEC-0117770, 0646547). We also acknowledge support of Cornell Center for Materials Research (CCMR) with funding from the Materials Research Science and Engineering Center program of the National Science Foundation (cooperative agreement DMR 0520404), and support of Energy Materials Center at Cornell (EMC<SUP>2</SUP>), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science under Award Number DE-SC0001086.