High‐Mobility Hydrophobic Conjugated Polymer as Effective Interlayer for Air‐Stable Efficient Perovskite Solar Cells

Hybrid organic–inorganic perovskite (HOIP) solar cells have achieved a certified power conversion efficiency (PCE) of 22.7%, which commonly use doped spiro‐OMeTAD as hole transport materials (HTMs). However, the additives in spiro‐OMeTAD can absorb moisture and cause the degradation of HOIP layers, leading to severe air‐instability of devices. Herein, conjugated polymers of PD‐10‐DTTE‐7 as a new effective interlayer between perovskite and doped spiro‐OMeTAD to achieve air‐stable efficient perovskite solar cells are reported. Its hydrophobic nature can effectively prevent the penetration of moisture and additives. Its superb hole mobility (9.54 cm 2 V −1 s −1 , ≈10 5 times higher than spiro‐OMeTAD) and suitable highest occupied molecular orbital level (−5.33 eV) are preferable to the hole injection and transport at the interface thus enhancing the device PCE. As a result, the MAPbI 3 solar cells with the PD‐10‐DTTE‐7 interlayer achieve remarkable device air‐stability and enhanced PCE, compared with the devices without the interlayer. These results provide a feasible approach to enhance solar cell stability and performance simultaneously.