Core/Shell PbSe/PbS QDs TiO 2 Heterojunction Solar Cell

Quasi type‐II PbSe/PbS quantum dots (QDs) are employed in a solid state high efficiency QD/TiO 2 heterojunction solar cell. The QDs are deposited using layer‐by‐layer deposition on a half‐micrometer‐thick anatase TiO 2 nanosheet film with (001) exposed facets. Theoretical calculations show that the carriers in PbSe/PbS quasi type‐II QDs are delocalized over the entire core/shell structure, which results in better QD film conductivity compared to PbSe QDs. Moreover, PbS shell permits better stability and facile electron injection from the QDs to the TiO 2 nanosheets. To complete the electrical circuit of the solar cell, a Au film is evaporated as a back contact on top of the QDs. This PbSe/PbS QD/TiO 2 heterojunction solar cell produces a light to electric power conversion efficiency ( η ) of 4% with short circuit photocurrent ( J sc ) of 17.3 mA/cm 2 . This report demonstrates highly efficient core/shell near infrared QDs in a QD/TiO 2 heterojunction solar cell.