High-Mobility p-Type Organic Semiconducting Interlayer Enhancing Efficiency and Stability of Perovskite Solar Cells.

A high-mobility p-type organic semiconductor based on benzodithiophene and diketopyrrolopyrrole with linear alkylthio substituents (BDTS-2DPP) is used as a dual function interfacial layer to modify the interface of perovskite/2,2',7,7'-tetrakis( N,N '-di- p -methoxyphenylamine)-9,9'-spirobifluorene in planar perovskite solar cells. The BDTS-2DPP layer can remarkably passivate the surface defects of perovskite through the formation of Lewis adduct between the under-coordinated Pb atoms in perovskite and S atoms in BDTS-2DPP, and also shows efficient hole extraction and transfer properties. The devices with BDTS-2DPP interlayer show a peak power conversion efficiency of 18.2%, which is higher than that of reference devices without the BDTS-2DPP interlayer (16.9%). Moreover, the hydrophobic BDTS-2DPP interlayer effectively protects the perovskite against moisture, leading to enhanced device stability.