Multifunctional Hole Transport Strategy for Highly Efficient and Stable Inverted Perovskite Solar Cells

Self-assembled monolayer (SAM)-based inverted perovskite solar cells (PSCs) have exhibited excellent performance in efficiency, while the stability and reproducibility of the PSCs still need to be improved. In this work, we present a multifunctional hole transport approach for inverted PSCs, where NiO_X, SAM ((E)-3-(4-(bis(4-methoxyphenyl)amino)phenyl)acrylic acid, abbreviated as MPTCA) and a wetting agent (2-phenylethylamine hydroiodide, known as PEAI) are employed for hole-transport materials (HTMs). This NiO_X/MPTCA/PEAI composite layer is uniform and has good wetting properties, which enables the formation of a high-quality perovskite film, effectively minimizing defects that typically occur at the buried interface. An outstanding champion efficiency of 24.74% was obtained for the devices, followed by enhanced reproducibility with an average power conversion efficiency (PCE) of 24.13 ± 0.26%, which is notably higher than that (22.73 ± 0.62%) of the pristine MPTCA-based PSCs. More importantly, the composited HTL-based devices without encapsulation demonstrated remarkable stability, with a decrease of less than 10% in the initial efficiency after 500 h of continuous light soaking.