A Fluorination Strategy and Low‐Acidity Anchoring Group in Self‐Assembled Molecules for Efficient and Stable Inverted Perovskite Solar Cells

Herein, we synthesized two donor‐acceptor (D‐A) type small organic molecules with self‐assembly properties, namely MPA‐BT‐BA and MPA‐2FBT‐BA, both containing a low acidity anchoring group, benzoic acid. After systematically investigation, it is found that, with the fluorination, the MPA‐2FBT‐BA demonstrates a lower highest occupied molecular orbital (HOMO) energy level, higher hole mobility, higher hydrophobicity and stronger interaction with the perovskite layer than that of MPA‐BT‐BA. As a result, the device based‐on MPA‐2FBT‐BA displays a better crystallization and morphology of perovskite layer with larger grain size and less non‐radiative recombination. Consequently, the device using MPA‐2FBT‐BA as hole transport material achieved the power conversion efficiency (PCE) of 20.32 % and remarkable stability. After being kept in an N2 glove box for 116 days, the unsealed PSCs’ device retained 93 % of its initial PCE. Even exposed to air with a relative humidity range of 30±5 % for 43 days, its PCE remained above 91 % of its initial condition. This study highlights the vital importance of the fluorination strategy combined with a low acidity anchoring group in SAMs, offering a pathway to achieve efficient and stable PSCs. Two self‐assembled hole transport materials with low acidity anchoring group, benzoic acid, and a fluorination strategy have been developed. With the new hole transport materials, high‐performance PSCs were fabricated with high‐quality perovskite layer and excellent interfacial contacts, and a champion PCE of 20.32 % was achieved with remarkably enhanced stability.