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Analyzing and Tuning the Chalcogen–Amine–Thiol Complexes for Tailoring of Chalcogenide Syntheses
journal contribution
posted on 2020-05-22, 17:03 authored by Swapnil
D. Deshmukh, Leah F. Easterling, Jeremy M. Manheim, Nicole J. LiBretto, Kyle G. Weideman, Jeffrey T. Miller, Hilkka I. Kenttämaa, Rakesh AgrawalThe
amine–thiol solvent system has been used extensively
to synthesize metal chalcogenide thin films and nanoparticles because
of its ability to dissolve various metal and chalcogen precursors.
While previous studies of this solvent system have focused on understanding
the dissolution of metal precursors, here we provide an in-depth investigation
of the dissolution of chalcogens, specifically Se and Te. Analytical
techniques, including Raman, X-ray absorption, and NMR spectroscopy
and high-resolution tandem mass spectrometry, were used to identify
pathways for Se and Te dissolution in butylamine–ethanethiol
and ethylenediamine–ethanethiol solutions. Se in monoamine–monothiol
solutions was found to form ionic polyselenides free of thiol ligands,
while in diamine–monothiol solutions, thiol coordination with
polyselenides was predominately observed. When the relative concentration
of thiol is increased to that of Se, the chain length of polyselenide
species was observed to shorten. Analysis of Te dissolution in diamine–thiol
solutions also suggested the formation of relatively unstable thiol-coordinated
Te ions. This instability of Te ions was found to be reduced by codissolving
Te with Se in diamine–thiol solutions. Analysis of the codissolved
solutions revealed the presence of atomic interaction between Se and
Te through the identification of Se–Te bonds. This new understanding
then provided a new route to dissolve otherwise insoluble Te in butylamine–ethanethiol
solutions by taking advantage of the Se2– nucleophile.
Finally, the knowledge gained for chalcogen dissolutions in this solvent
system allowed for controlled alloying of Se and Te in PbSenTe1–n material
and also provided a general knob to alter various metal chalcogenide
material syntheses.