Impact of the Growth Conditions of Colloidal PbS Nanocrystals on Photovoltaic Device Performance

Here, we present a detailed investigation on the influence of the growth conditions of colloidal lead sulfide (PbS) nanocrystals on photovoltaic device performance. The PbS nanocrystals were synthesized in a noncoordinating solvent, 1-octadecene, using oleic acid (OA) as the ligand. It was found that both the feeding molar ratio of OA to Pb and the reactant concentration were critical for controlling the growth rate of nanocrystals. Transient photocurrent (TPC) measurements revealed reduced trap density in thin films using the slow-growth nanocrystals. Solar cells based on the slow-growth nanocrystals showed a high power conversion efficiency (PCE) of 3.8% under simulated Air Mass 1.5 Global (AM 1.5G) irradiation (100 mW/cm(2)), a 2-fold increase in PCE, compared to the fast-growth nanocrystals, because of the remarkable improvement in the open-circuit voltage and fill factor in the PV devices.