Nickel‐Free Perovskite Solar Cells Enabled by Self‐Assembled Monolayers: A Pathway to Efficient and Recyclable Devices

ABSTRACT High efficiency inverted perovskite solar cells often rely on nickel‐containing hole‐selective interfaces such as NiOx. However, the use of nickel presents sustainability challenges, as the material is inherently toxic and cross‐contamination during end‐of‐life processing can compromise material recovery and recyclability. Here, we develop a nickel‐free hole‐selective interface material based on phenyl‐substituted phosphonic‐acid carbazole self‐assembled monolayers (Ph‐nPACz). Candidate molecules were identified through rational structure‐property screening of the substituents of the carbazole core, anchoring groups and linkers. Among this molecular family, Ph‐5PACz delivers the best overall performance, offering improved interfacial wettability and enhanced buried‐interface stability compared to the NiOx/Me‐4PACz reference. Devices incorporating Ph‐5PACz achieve a power conversion efficiency of 25.3%, compared to 21.7% for the control, driven by a higher fill factor and efficient charge extraction. The chemical robustness of the nickel‐free interface enables a closed‐loop recycling route unavailable to nickel‐based devices, with recycled‐ITO devices retaining close to 98% of their initial performance. Coupled life‐cycle and techno‐economic analyses further indicate substantial sustainability gains, including reduced energy demand, markedly lower raw metal usage and toxicity‐related impacts, and a generalized reduction of up to 29% across ReCiPe endpoint indicators.