Revealing the Impacts of Molecular Rigidity and Orientation on Interfacial Contact in Efficient Perovskite Solar Cell.

Self-assembled monolayers (SAMs) are widely employed as hole transport layers in inverted perovskite solar cells (PSCs), but suffer from insufficient surface coverage and difficulties in spin-coating a perovskite film on top. Herein, we design and synthesize two novel corannulene derivatives, 3-(corannulen-1-yl)acrylic acid (CorAcA) and 3-(corannulen-1-yl)propionic acid (CorPrA), which successfully address the SAM/perovskite interfacial problems. Beyond achieving promising photovoltaic performance and operational stability in the PSCs, we provide deep insight into how molecular rigidity and orientation influence interfacial contact within the devices, thereby enabling us to identify the key factor responsible for the enhanced device performance and stability. We demonstrate that the more flexible linker (C-C) between the corannulene core and the anchoring group (-COOH) endows CorPrA with better orientational adaptability and interfacial contact compared to the rigid linker (C = C) of CorAcA. This not only generates a vertical interfacial dipole that facilitates efficient charge carrier dynamics but also distinctly improves the perovskite film quality, thus optimizing the fill factor and operational stability of the PSCs. This study underscores the importance of regulating molecular rigidity and orientation at device interfaces, providing a new paradigm for interfacial design toward highly efficient and stable PSCs.