Abstract
The use of solution-processed self-assembled monolayers (SAMs) to passivate metal oxide thin films is an effective approach for high-performance perovskite solar cells. However, commonly used SAMs suffer from poor uniformity and wettability issues in ultrathin layers (<10 nm), leading to incomplete coverage. This limits their suitability for scalable slot-die coating. In this work, we synthesized a 4,4′,4″-nitrilotribenzoic acid (TPA-3C) that directly addressing the solvatophobicity and wetting mismatch of conventional carbazole-phosphonic acid SAMs under slot die processing. The three functionalities and star-shaped symmetry of the TPA-3C molecule make it possible to avoid orientation of the molecule with the non-anchoring groups toward the substrate during solution printing. Molecular engineering of a tri-functional triphenylamine core provides simultaneous control of wettability and surface potential, which translates into highly uniform SAM coverage and perovskite crystallization. We made a special focus on data fluctuations, standard deviation on recombination, transport and photoelectric performance of devices and modules. Slot die coating was implemented for both the SAM and CsFAPbI3 absorber in p i n devices and 12 cell modules, yielding champion power conversion efficiencies of 19.2% and 16.3%, respectively, together with relevant operational and thermal stability (>1000 h, ISOS-L-2). Correlating local non-uniform wetting spots with lifetime, dark saturation current, and temperature coefficients reveals that mitigating SAM-induced wetting defects is essential for scalable, stable perovskite photovoltaics.