Intermolecular Coupling Reinforces Self‐Assembled Hole‐Transport Layers Stability and Performance in NiO _x ‐Based Inverted Perovskite Solar Cells

ABSTRACT NiO x hole transport layers modified with phosphonic acid‐based self‐assembled monolayers (SAMs) offers a promising strategy to resolve buried interface issues in NiO x ‐based inverted perovskite solar cells (IPSCs). However, SAMs efficacy is hindered by molecular aggregation, strong acidity, and anchoring instability, restricting their interfacial modification capabilities. Here, leveraging an intermolecular coupling strategy, hybrid SAMs (H‐SAMs) is first designed for NiO x /perovskite interface modification, where triphenylamine (TPA)‐based boronic acid molecule (MeO‐TPABA) serves as coupling agent to integrate with MeO‐2PACz. The multidirectional π‐π interaction and more conjugated structural features provided by MeO‐TPABA effectively suppress the aggregation behavior of MeO‐2PACz molecules and improve the interfacial electrical transport kinetics. Notably, this intermolecular coupling strategy converts individual molecules’ single‐point anchoring into multi‐point anchoring of 2D coupled molecular layer, while enhancing the anchoring strength of SAMs’ anchoring groups—thus significantly boosting molecular anchoring density and stability. Benefiting from this strategy, H‐SAMs improves anode interface contact, carrier transport, perovskite film quality, and reduces residual stress, thereby notably enhancing device performance and stability. The best power conversion efficiency (PCE) of 26.18% is achieved, which is among the highest values reported for hybrid SAMs‐modified NiO x ‐based IPSCs. Furthermore, the device based on the H‐SAMs exhibits excellent stability under thermal, moisture and illumination.