Lattice‐Matching Structurally‐Stable 1D@3D Perovskites toward Highly Efficient and Stable Solar Cells

Abstract The stability of perovskite solar cells (PSCs) has been identified to be the bottleneck toward their industrialization. With the aim of tackling this challenge, a 1D PbI 2 ‐bipyridine (BPy)(II) perovskite is fabricated, which is shown to be capable of in situ assembly of a 1D@3D perovskite that is promoted by a PbI 2 ‐dimethyl sulfoxide complex with a skeletal linear chain structure. The as‐prepared 1D@3D perovskite is observed to demonstrate extremely high stability under external large electric fields in humid environments by means of an in situ characterization technique. This stability is associated with its well lattice‐matching heterojunction structure between 1D and 3D heterojunction domains. Importantly, ion migration is alleviated through blocking of the ion‐migration channels. Accordingly, the 1D@3D hybrid PSC shows a power conversion efficiency of 21.18% maintaining remarkably high long‐term stability in the presence of water, illumination, and external electric fields. This rational design and microstructure study of 1D@3D perovskites provides a new paradigm that may enable higher efficiency and stability of PSCs.