Noncovalent Conformational Dopant‐Free Hole Transport Materials with Multisite Passivation for Stable n‐i‐p Perovskite Solar Cells

Abstract High‐performance, dopant‐free hole transport materials (HTMs) play a crucial role in stabilized perovskite solar cells (PSCs). Skillfully using noncovalent bonding strategies to construct dopant‐free HTM is both attractive and challenging. In this work, two dopant‐free HTMs with multisite passivation are designed and synthesized. The core backbone is a heterocyclic lactam, and the intramolecular F···S noncovalent bonds are tuned by adjusting the position of F atoms. In TTPA‐iF molecule, the noncovalent conformational lock minimizes the rotation of the core‐terminal unit. This, in turn, reduces unfavorable reorganization energy and increases the molecular dipole moment. Compared to the amorphous films of TTPA‐mF, the TTPA‐iF films exhibit ordered molecular stacking and higher hole mobility. The rigid molecular conformation of TTPA‐iF allows for more effective reduction of interfacial traps through multiple passivation sites and promotes carrier transport. As a result, PSCs with dopant‐free TTPA‐iF achieve a top efficiency of 24.28% and show significantly enhanced stability under various conditions in comparison to conventional doped HTMs. This research offers valuable insights and material options for the development of high‐performance, dopant‐free HTMs.