Compositional Optimization of Photovoltaic Grade Cu2ZnSnS4 (CZTS) Films Synthesized by Colloidal Route

In recent years, kesterite structured Cu2ZnSn(S, Se)(4) materials have attracted significant interest as second generation solar cell material. However, the capability of reproducibly synthesizing these nanocrystal (NC) inks with accurately controlled and specific compositions is very crucial for making efficient solar cell devices. In this work rod shaped CZTS nanoparticles are synthesized by cost effective and rapid hot injection technique using TOPO-TOP as capping ligand for various Zn/ Sn precursor ratios. Since, for good solar cell device material (here, CZTS nanocrystals) higher zinc concentration are required so here, we varies zinc concentration and we find that mere increase in zinc amount in precursors for the synthesis of CZTS nanocrystals may not be necessarily advantageous for solar cell application. It should be optimized with respect to tin (Sn), phosphorus (P) and copper (Cu) for best PV properties and we find that incorporation of zinc into CZTS is higher in case where zinc amount is less in precursors. Different aspects of these nanorods are analyzed by EDAX, contact angle, transmission electron microscopy (TEM) and photoluminescence spectroscopy respectively.