Morphological growth and phase formation of CuInSe2 nanocrystals by an ambient pressure polylol-based solution synthesis

Single-phase and well-dispersed CuInSe2 nanoparticles and nanoplates were successfully synthesized through an ambient pressure solution chemical process using green triethylene glycol (TEG) as solvent, copper(II) chloride, indium(III) chloride and selenium powder as precursor sources. Morphological growth of the CuInSe2 nanoparticles and nanoplates synthesized respectively with the hydrazine- and ethylenediamine-assisted TEG reaction solution was investigated by XRD, TEM, HRTEM, SAED, XPS and EDX analysis. The results showed that the growth process of CuInSe2 nanoparticles derived from the hydrazine-assisted solution only underwent quick reduction reaction of elemental Se to Se2− and cupric Cu2+ to Cu+ to directly form the ternary compound. The growth of CuInSe2 nanoplates derived from the ethylenediamine-assisted solution involved in the formation of intermediate phase CuSe with lamellar morphology and subsequently a transformation of the CuSe phase into CuInSe2 phase by gradual reduction of cupric Cu2+ to cuprous Cu+, In3+ and active Se2− participation at growing lattice sites.