Axial Composition
Gradients and Phase Segregation
Regulate the Aspect Ratio of Cu<sub>2</sub>ZnSnS<sub>4</sub> Nanorods
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Abstract
Cu<sub>2</sub>ZnSnS<sub>4</sub> (CZTS) is a promising material
for solar energy conversion, but synthesis of phase-pure, anisotropic
CZTS nanocrystals remains a challenge. We demonstrate that the initial
concentration (loading) of cationic precursors has a dramatic effect
on the morphology (aspect ratio) and composition (internal architecture)
of hexagonal wurtzite CZTS nanorods. Our experiments strongly indicate
that Cu is the most reactive of the metal cations; Zn is next, and
Sn is the least reactive. Using this reactivity series, we are able
to purposely fine-tune the morphology (dots versus rods) and degree
of axial phase segregation of CZTS nanocrystals. These results will
improve our ability to fabricate CZTS nanostructures for photovoltaics
and photocatalysis