Dopant‐Free Pyrene‐Based Hole Transporting Material Enables Efficient and Stable Perovskite Solar Cells

Abstract Dopant‐free hole transporting materials (HTMs) is significant to the stability of perovskite solar cells (PSCs). Here, we developed a novel star‐shape arylamine HTM, termed Py‐DB, with a pyrene core and carbon‐carbon double bonds as the bridge units. Compared to the reference HTM (termed Py‐C), the extension of the planar conjugation backbone endows Py‐DB with typical intermolecular π–π stacking interactions and excellent solubility, resulting in improved hole mobility and film morphology. In addition, the lower HOMO energy level of the Py‐DB HTM provides efficient hole extraction with reduced energy loss at the perovskite/HTM interface. Consequently, an impressive power conversion efficiency (PCE) of 24.33 % was achieved for dopant‐free Py‐DB‐based PSCs, which is the highest PCE for dopant‐free small molecular HTMs in n‐i‐p configured PSCs. The dopant‐free Py‐DB‐based device also exhibits improved long‐term stability, retaining over 90 % of its initial efficiency after 1000 h exposure to 25 % humidity at 60 °C. These findings provide valuable insights and approaches for the further development of dopant‐free HTMs for efficient and reliable PSCs.