Dipole Formation at the MoO3/Conjugated Polymer Interface

Abstract

AbstractMoO3 is known as high work function (WF) transparent metal oxides. It is used as anode buffer layer in organic based solar cells because of its capability to extract electrons and inject holes from the active layer due to its high WF. Here a broad range of techniques is used to determine the energy levels of the bulk heterojunction (BHJ) and MoO3 to determine that the minimum deposition thickness to achieve a closed layer is 1 nm due to penetration of the evaporated MoO3 into the BHJ. The investigation shows that upon evaporation of the MoO3, a strong dipole is formed at the extended interface between the active layer and the MoO3 and that the strength of the dipole increases with increasing thickness of the MoO3 layer and saturates at 2.2 eV at a thickness around 3 nm.