title: General low-temperature reaction pathway from precursors to monomers before nucleation of compound semiconductor nanocrystals.
abstract: Little is known about the molecular pathway to monomers of semiconductor nanocrystals. Here we report a general reaction pathway, which is based on hydrogen-mediated ligand loss for the precursor conversion to 'monomers' at low temperature before nucleation. We apply (31)P nuclear magnetic resonance spectroscopy to monitor the key phosphorous-containing products that evolve from MXn+E=PPh2H+HY mixtures, where MXn, E=PPh2H, and HY are metal precursors, chalcogenide precursors, and additives, respectively. Surprisingly, the phosphorous-containing products detected can be categorized into two groups, Ph2P-Y and Ph2P(E)-Y. On the basis of our experimental and theoretical results, we propose two competing pathways to the formation of M2En monomers, each of which is accompanied by one of the two products. Our study unravels the pathway of precursor evolution into M2En monomers, the stoichiometry of which directly correlates with the atomic composition of the final compound nanocrystals.
authors.affiliation: Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610065, China.
authors.forename: Kui
authors.initials: K
authors.lastname: Yu
authors.affiliation: Security and Disruptive Technologies, National Research Council Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Qi
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Huaqing
authors.initials: H
authors.lastname: Yang
authors.affiliation: Security and Disruptive Technologies, National Research Council Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Whitfield
authors.affiliation: Security and Disruptive Technologies, National Research Council Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Queena
authors.initials: Q
authors.lastname: Y Chen
authors.affiliation: Security and Disruptive Technologies, National Research Council Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Erik J C
authors.initials: EJ
authors.lastname: Huisman
authors.affiliation: Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610065, China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Hu