Quasi type-II PbSe/PbS quantum dots (QDs) are employed in a solid state high efficiency QD/TiO2 heterojunction solar cell. The QDs are deposited using layer-by-layer deposition on a half-micrometer-thick anatase TiO2 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 TiO2 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/TiO2 heterojunction solar cell produces a light to electric power conversion efficiency () of 4% with short circuit photocurrent (Jsc) of 17.3 mA/cm2. This report demonstrates highly efficient core/shell near infrared QDs in a QD/TiO2 heterojunction solar cell.