Terminal Group Effects on Molecular Organization and Charge Extraction in Self-Assembled Monolayers/Perovskite Interfaces.

The structural nature of self-assembled monolayers (SAMs) critically determines interfacial quality, film formation, and charge transport in inverted perovskite solar cells (iPSCs). While variations in SAM functional groups have been explored, these studies have focused on their impact on device performance metrics. In contrast, a fundamental understanding of how subtle molecular structural variations govern the molecular organization of SAMs, and how it modulates surface energy, interfacial properties, and the growth of perovskite films deposited atop these monolayers, remains limited. In addition, as perovskite technology advances toward industrial deployment, gaining fundamental insight into how SAMs govern film quality is essential for guiding the development of efficient and stable devices. Here, we systematically investigate the effects of SAM terminal groups (electron-withdrawing, neutral, and electron-donating) on the morphology and optoelectronic properties of perovskite films. Our results demonstrate that the electronic nature of the terminal group plays a decisive role in determining SAM molecular organization, which in turn directly affects interfacial hole extraction efficiency.