No abstract

Thermal decomposition of the molecular single-source precursor (PPh 3 ) 2 CuIn(SEt) 4 in the presence of hexanethiol in dioctylphthalate forms colloidal CuInS 2 at 200 °C. The colloidal solution displays size-dependent quantum confinement behavior in the absorption and photoluminescence spectra. The average size of the nanocrystals can be increased from 2 to 4 nm by raising the reaction temperature from 200 °C to 250 °C. The nanoparticles are capped with hexanethiol ligands; these ligands can be exchanged with trioctylphosphine oxide or pyridine. The nature of the surface-capping ligands has a significant effect on the photoluminescence emission intensity. Investigation of the effect of synthesis parameters and postsynthesis treatments on the optical properties of the nanocrystals leads to the conclusion that the room-temperature emission originates in donor-acceptor defects.

Nanometer-sized particles of the chalcopyrite compounds CuInS 2 and CuInSe 2 were synthesized by thermal decomposition of molecular single-source precursors (PPh 3 ) 2 CuIn-(SEt) 4 and (PPh 3 ) 2 CuIn(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.