Embedded CdS nanorod arrays in PbS absorber layers: enhanced energy conversion efficiency in bulk heterojunction solar cells

Oriented and high-density n-type CdS nanorod arrays were successfully embedded in p-type PbS absorber layers by a facile and low-cost hydrothermal method and a chemical bath deposition method. The structural, optical and electrical properties of these samples were examined, and the results demonstrated that the high quality three-dimensional heterostructure was obtained. Further investigation revealed that the three-dimensional heterostructure possessed superior optical absorption property due to the optical scattering from the nanorod array. In addition, photovoltaic property measurements demonstrated that the energy conversion efficiency of the novel three-dimensional heterojunction solar cell was increasing by 35% in comparison with the standard planar heterojunction solar cell. The observed improvement is mostly attributed to the three-dimensional heterostructure enabling increased heterojunction area, improved charge carrier collection and enhanced optical absorption ability. This study demonstrates that the three-dimensional heterostructure has potential application in thin film solar cells, and the solution process represents a promising technique for large-scale fabrication of these novel solar cells.