Improvement of Solar Cell Characteristics Using PbS Quantum Dot Superlattice Prepared by Sedimentation

Abstract

We report the characteristics of organic solar cells on Si substrates using quantum dot superlattices (QDSLs) prepared by sedimentation. When colloidal quantum dots (QDs) are deposited on a substrate in a solvent, they are closely packed and form multiple grains in a film. We found that the PbS QD grains grew into a large superlattice when the deposition proceeded for a long period of time. A solar cell was fabricated using the QD superlattice film as an absorbing layer. When the deposition was slow, the short-circuit current density of the solar cell doubled compared with that of the rapid deposition case. Simulations based on the superposition model suggest that the superlattice formation process is responsible for the observed change in the cell characteristics.