Highly Efficient and Stable Perovskite Solar Modules Based on FcPF₆ Engineered Spiro-OMeTAD Hole Transporting Layer

Li-TFSI doped spiro-OMeTAD is widely recognized as a beneficial hole transport layer (HTL) in perovskite solar cells (PSCs), contributing to high device efficiencies. However, the uncontrolled migration of lithium ions (Li⁺) during device operation has impeded its broad adoption in scalable and stable photovoltaic modules. Herein, an additive strategy is proposed by employing ferrocenium hexafluorophosphate (FcPF₆) as a relay medium to enhance the hole extraction capability of the spiro-OMeTAD via the instant oxidation function. Besides, the novel Fc-Li interaction effectively restricts the movement of Li⁺. Simultaneously, the dissociative hexafluorophosphate group is cleverly exploited to regulate the unstable iodide species on the perovskite surface, further inhibiting the formation of migration channels and stabilizing the interfaces. This modification leads to power conversion efficiencies (PCEs) reaching 22.13% and 20.27% in 36 cm² (active area of 18 cm²) and 100 cm² (active area of 56 cm²) perovskite solar modules (PSMs), respectively, with exceptional operational stability obtained for over 1000 h under the ISOS-L-1 procedure. The novel FcPF₆-based engineering approach is pivotal for advancing the industrialization of PSCs, particularly those relying on high-performance spiro-OMeTAD- based HTLs.