In Situ Seeded Growth of High-Quality PbS/CdS Quantum Dots for Highly Efficient Photovoltaics

Panchromatic solar cells are of great prospects in virtue of the sufficient utilization of solar energy. The narrow bandgap semiconductors such as PbS can serve as promising candidates for light harvesting. In this paper, we report an in situ seeded growth of PbS quantum dots (QDs) onto TiO 2 films for the construction of high-performance PbS/CdS QD-sensitized solar cells. Careful morphologic, optical, and electrical examinations were performed to probe into the superiority of such an approach. The predeposited PbSO 3 seeds are used as nucleation sites for monodisperse PbS QDs with the particle size of ∼3.5 nm, which ensures favorable electron injection from PbS into TiO 2 . Meanwhile, the CdS passivation layer is synchronously loaded along with in situ seeded PbS, resulting in effective passivation of defect states at the PbS surface. Eventually, benefitted from improved carrier manipulation (i.e., electron injection and charge transport), the in situ seeded device yields a power conversion efficiency of 2.13%, exhibiting considerably enhanced photovoltaic performance in contrast to the identical PbS/CdS scheme processed by the conventional two-step successive ionic layer adsorption and reaction.