Synthesis of Quaternary Semiconductor Nanocrystals with TunableBand Gaps

摘要

Dispersible quaternary Cu_(1.0)Ga_xIn_(2-x)S_(3.5) and Cu_(1.0)In_xTl_(2-x)S_(3.5) nanocrystals were successfully prepared by a toluene-thermal and a hot-injection approach and characterized using UV-vis spectroscopy, X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). UV-vis absorption spectra of Cu_(1.0)Ga_xIn_(2-x)S_(3.5) nanocrystals revealed that the band gaps of alloyed nanocrystals can be precisely adjusted in the range of 1.43 to 2.42 eV by increasing the indium content. From XRD analysis, the lattice parameters of Cu_(1.0)Ga_xIn_(2-x)S_(3.5) nanocrystals decreased linearly with an increase in the Ga/(Ga + In) ratio in accordance with Vegard's law, which confirmed that alloyed nanocrystals have a homogeneous structure. Alloyed Cu_(1.0)Ga_xIn_(2-x)S_(3.5) and Cu_(1.0)In_xTl_(2-x)S_(3.5) nanocrystals have a narrow size distribution according to TEM analysis results. Moreover, it was found that oleylamine played an important role in the formation quaternary homogeneous Cu_(1.0)Ga_xIn_(2-x)S_(3.5) and Cu_(1.0)In_xTl_(2-x)S_(3.5) nanocrystals due to eliminating the reactivity difference of copper, gallium, and indium as well as thallium precursors.