SAM Molecular Stacking with Heterogeneous Orientationfor High-Performance Perovskite Photovoltaics

The inability to achieve uniform hole transport with solution-processed self-assembled monolayers (SAM) constitutes a fundamental bottleneck for scaling perovskite photovoltaics. Herein, we demonstrate that thermal-evaporated SAM (eSAM) overcome this by enabling precise thickness control. Crucially, a thickened eSAM spontaneously forms a vertical-to-horizontal gradient in molecular orientation, which creates a descending energy barrier that directionally facilitates hole transport. This tailored interface also ensures excellent surface coverage and directs the growth of high-quality perovskite films. Consequently, the resultant photovoltaic devices set new benchmarks, delivering impressive power conversion efficiencies (PCEs) of 21.46% (small-area, 0.108 cm2) and 19.38% (large-area module, 15.52 cm2) for fully vacuum-evaporated devices, while also setting an impressive PCE of 23.67% for eSAM-based devices with solution-processed perovskites. The unencapsulated devices also present excellent operational stability by retaining 91.9% initial efficiency after 1200 hours continuous MPPT testing. The new strategy effectively addresses the critical challenge of scalable SAM deposition, positioning eSAM as a key enabler for the industrial advancement of perovskite photovoltaics.