CsPbI_<b>3</b> Nanorod Additive Engineering: Enhancing Efficiency and Stability in Mixed-Cation CsMAFAPbI_<b>3</b> Perovskite Solar Cells

In this work, we incorporate CsPbI3 nanorods into a triple-cation mixed perovskite matrix (Cs0.1MA0.1FA0.8PbI3). The CsPbI3 nanorod additive serves as nucleation centers, regulating the crystallization process and promoting the growth of larger perovskite domains with fewer grain boundaries, without altering the bandgap. Consequently, the resulting perovskite films exhibit improved crystallinity, reduced trap-state density, and suppressed nonradiative recombination, thereby facilitating enhanced charge extraction. The optimized device achieves a power conversion efficiency (PCE) of 21.13%, compared to 18.01% for the control device, primarily attributed to enhancements in the fill factor (FF) and open-circuit voltage (Voc). Furthermore, the incorporation of nanorods enhances the hydrophobicity and moisture resistance of the perovskite films, enabling the device to retain 87% of its initial efficiency after 384 h under an inert atmosphere. This study underscores nanorod-based additive engineering as a promising strategy for simultaneously improving the efficiency and environmental stability of perovskite solar cells.