A novel bifunctional linker molecule, bis(4-mercaptophenyl)phosphinic acid, is designed to be used in a QDs solar cells. The linker anchors to TiO2 mesoporous film through the phosphinic acid functional group and to the PbS QDs through the two thiol groups. The way of attachment of this new linker molecule in a photovoltaic PbS QDs/TiO2 mesoporous device was studied by FTIR measurements. The photovoltaic performance of this new linker in a heterojunction PbS QDs solar cell show high V-oc c relative to QDs based solar cells, which will allow to receive high power conversion efficiency using this novel designed linker. This novel bifunctional linker molecule should pave the way for enhancing binding strength, and efficiency of QDs solar cells compared to the state-of-the-art linkers.