A robust method for the synthesis of colloidal PbS nanosheets

Two dimensional colloidal PbS semiconductor materials are interested in low cost and easy processable thin plate optoelectronic and photovoltaics devices such as solar cells and transistors. Here we report a robust method by which colloidal PbS nanosheets can be synthesized with nearly 100{\%} success rate. It is achieved by replacing lead acetate with lead oxide to prepare the lead precursor for the reaction. Acetic acid either injected externally or produced during the reaction has a significant effect on the growth of the nanosheets by turning them into three-dimensional clusters. In the new synthesis, the purity of trioctylphosphine (the co-solvent for sulfur precursor) has no significant effect on the formation of nanosheets. Thickness tunability is also achieved in the acetic-acid-free synthesis.