Synthesis of high quality PbS colloidal quantum dots by ultrasonic bath as photosensitizers in a TiO2 solar cell

We report a novel and simple method for the synthesis of high quality PbS colloidal quantum dots (CQDs) by controlled precipitation between Pb2+ cations and S2− anions inside aqueous nanodroplets that are generated by an ultrasonic bath operated at 35 ​kHz frequency. The synthesized PbS CQDs have cubic crystal structure with an average particle size of 6.8 ​nm, a size dispersion of 15% and an optical band gap of 0.72 ​eV. PbS CQDs were deposited uniformly by electrophoretic method on a TiO2 photoelectrode applying 200 ​V for 60 ​min and used as photosensitizers in a TiO2 solar cell. Their photovoltaic parameters were studied under 1 sun illumination. Remarkably, we obtain power conversion efficiencies similar to those found in TiO2 sensitized solar cells made with high quality PbS CQDs synthesized by hot injection method. High quality PbS colloidal quantum dots synthesized by ultrasonic bath and their use as photosensitizers in a TiO2 solar cell. [Display omitted] •High quality PbS colloidal quantum dots synthesized by ultrasonic bath.•PbS CQD have cubic crystal structure and 6.8 ​± ​1.02 ​nm nanoparticle size.•Quantum dot sensitized solar cells are fabricated with the PbS CQD.•PCE is similar to solar cells made with hot injection PbS CQD.