Characterization of calcined CuInS2 nanocrystals prepared by microwave-assisted synthesis

• CuInS2 nanocrystals have been produced by the method of microwave-assisted synthesis.
• XRD, FTIR, SEM, Raman and transmission properties have been studied.
• The particle size is increased as the increasing of calcined temperature.
• Raman property was influenced due to the increasing of calcined temperature.

In this work, CuInS2 (CIS) nanocrystals are successfully synthesized by microwave-assisted technique and further calcined at several different temperatures with or without additional Ar ambient. The XRD measurements showed that a significant recrystallization might have occurred with the help of Ar ambient to introduce the increasing relative intensity of the (112) diffraction peak. Furthermore, the eliminated organic-related structures and the enlarging CuInS2 nanocrystals are evidently confirmed by FTIR and SEM, respectively. Raman analysis of the CIS(CH) mode of the CuInS2 nanocrystals in the calcined temperature range of 200–400 °C is presented while the lineshape is described and calculated by the spatial correlation model corresponding to the presence of a long-range order in the higher calcined temperature of CuInS2 nanocrystals. Transmission can be used to figure out that the calcined CuInS2 nanocrystals with Ar are related with the modification of the optical band gap energy.