Cu 2ZnSnS 4 (CZTS) nanocrystals (NCs) were synthesized by sulfurization of microwave assisted precursor powders without toxic chemicals. The effects of different Cu concentration from 0.01 to 0.025 M on the structural, morphological, compositional, chemical and optical properties of CZTS NCs were investigated. X-ray diffraction patterns, X-ray photoelectron spectroscopy and transmission electron microscopy results showed that the precursor powder contains several broad peaks that could not be assigned to CZTS, ZnS, Cu 2-xS, Sn 2S 3 and Cu 2SnS 3. However, the sulfurized NCs showed both kesterite CZTS and Cu- and Sn-based secondary phases except for that formed at Cu concentration of 0.02 M. Inductively coupled plasma (ICP) results showed that the presence of Cu in the sulfurized CZTS NCs increased with increasing Cu concentration from 16.57 to 32.94 at.% while Zn and Sn in the sulfurized CZTS NCs decreased with increasing Cu concentration. UV-Vis spectroscopy results showed that the absorption coefficient of the sulfurized NCs was over 10 4 cm -1 in the visible region and band gap energy of the sulfurized CZTS NCs decreased from 1.65 to 1.28 eV with increasing Cu concentration.
Bibliographical noteFunding Information:
This study was supported partially by National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST No. 2011-0016564) and by the Center for Inorganic Photovoltaic Materials (2012-0001170) grant funded by Korea government.
- Cu ZnSnS (CZTS) absorber material
- Cu concentration
- Facile and low cost microwave assisted process
- Nanocrystal (NCs)