Nanocrystalline Chalcopyrite Materials (CuInS₂and CuInSe₂) via Low-Temperature Pyrolysis of Molecular Single-Source Precursors

Abstract

Nanometer-sized particles of the chalcopyrite compounds CuInS2 and CuInSe2 were synthesized by thermal decomposition of molecular single-source precursors (PPh3)2CuIn(SEt)4 and (PPh3)2CuIn(SePh)4, respectively, in the noncoordinating solvent dioctyl phthalate at temperatures between 200 and 300 °C. The nanoparticles range in size from 3 to 30 nm and are aggregated to form roughly spherical clusters of about 500 nm in diameter. X-ray diffraction of the nanoparticle powders shows greatly broadened lines, indicative of very small particle sizes, which is confirmed by TEM. Peaks present in the XRD can be indexed to reference patterns for the respective chalcopyrite compounds. Optical spectroscopy and elemental analysis by energy dispersive spectroscopy support the identification of the nanoparticles as chalcopyrites.