Controlling the Lateral Size and Excitonic Properties of Colloidal PbS Nanosheets

Abstract By changing the precursor lead‐to‐sulfur molar ratio in the synthesis of colloidal PbS nanosheets, the lateral size of the nanosheet can be tuned in a wide range from 100 nm to 1500 nm while keeping its thickness around 2.4 nm. Using chloroalkane molecules with a long carbon‐chain as the capping ligands can further reduce the lateral size down to 20 nm. The concentration of the chloroalkane in the reaction solution and the reaction temperature also have significant effects on the lateral size. At room temperature, nanosheets with a small lateral size exhibit a narrow light‐emission linewidth. The same nanosheets also show a sharp exciton peak near the band edge in the optical absorption spectrum.