Bifacial carbodithioate-lead chelating for efficient and robust inverted perovskite solar cells

Low-dimensional conversion of lead iodide at perovskite grain boundaries (GBs) is of importance to address the interfacial instability of perovskite solar cells (PSCs), while current strategies relying on organic cations interacted with A/X site to low-dimensional lead-halide complexes are challenged by the instability caused by the introduction or residual cations and halides in perovskite films. Present work proposes and verifies a strategy of multidentate carbodithioate-lead chelation (MCLC), which is able to form a robust one-dimensional structure at the GBs, not only reducing interfacial defects and residual stress but also enhancing interfacial carrier transport in perovskite while substantially improving the photothermal and operational stabilities of PSCs. It was further demonstrated that bifacial modification at both top and buried interfaces of perovskite using MCLC strategy achieved PSCs with a high power conversion efficiency up to 26.15% (certified value of 25.75%) and 24.89% for 1-cm²-area device. The device retains 90.1% of its initial efficiency after 1700 hours of maximum power point tracking under illumination.