Mo⁵⁺ doping induced interface polarization for improving performance of planar perovskite solar cells

In this paper, we investigate how interface-induced polarization affects the photovoltaic performance of hybrid perovskite solar cell (PSC) devices. The polarization of the hole transport layer (HTL) is regulated through incorporating metallic-like MoO_x into PEDOT:PSS. The common MoO₃ doped into PEDOT:PSS is used as a reference, and the device that used PEDOT:PSS-MoO_x as the HTL shows an enhanced J _sc and FF compared to the reference device. The open-circuit photovoltage decay and impedance spectroscopy measurements indicate that trap-assisted recombination is effectively suppressed at the interface between the hybrid perovskite and the PEDOT:PSS-MoO_x HTL, while severe trap assisted recombination takes place at the perovskite/PEDOT:PSS and perovskite/PEDOT:PSS-MoO₃ interface. We attribute these experimental findings to the fact that the incorporation of metallic-like Mo⁵⁺ into PEDOT:PSS enhances the conductivity of HTL and the interface polarization between PEDTOT:PSS layer and perovskite, which helps to induce an interface polarization electric field to facilitate separation of charges and screen the recombination between the traps and free charges. (paper)