Evolution
of Self-Assembled ZnTe Magic-Sized Nanoclusters
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Abstract
Three families of ZnTe magic-sized
nanoclusters (MSNCs) were obtained
exclusively using polytellurides as a tellurium precursor in a one-pot
reaction by simply varying the reaction temperature and time only.
Different ZnTe MSNCs exhibit different self-assembling or aggregation
behavior, owing to their different structure, cluster size, and dipole–dipole
interactions. The smallest family of ZnTe MSNCs (F323) does not reveal
a crystalline structure and as a result assembles into lamellar triangle
plates. Continuous heating of as synthesized ZnTe F323 assemblies
resulted in the formation of ZnTe F398 MSNCs with wurzite structure
and concomitant transformation into lamellar rectangle assemblies
with the organization of nanoclusters along the ⟨002⟩
direction. Further annealing of ZnTe F398 assembled lamellar rectangles
leads to full organization of MSNCs in all directions and formation
of larger ZnTe F444 NCs that spontaneously form ultrathin nanowires
following an oriented attachment mechanism. The key step in control
over the size distribution of ZnTe ultrathin nanowires is, in fact,
the growth mechanism of ZnTe F398 MSNCs; namely, the step growth mechanism
enables formation of more uniform nanowires compared to those obtained
by continuous growth mechanism. High yield of ZnTe nanowires is achieved
as a result of the wurzite structure of F398 precursor. Transient
absorption (TA) measurements show that all three families possess
ultrafast dynamics of photogenerated electrons, despite their different
crystalline structures