Since the breakthrough in power conversion efficiency when perovskite materials are used in planer‐type solar cells, researchers have tried to apply perovskite materials into fiber‐shaped solar cells in order to achieve higher power conversion efficiency. However, the difficulty of film fabrication on the fiber surface makes it difficult to obtain a high‐quality perovskite film layer, and to obtain a large improvement in performance. In this work, the vapor‐assisted deposition method is creatively applied in the preparation of fiber‐shaped solar cells, and realizing the purpose of growing a high‐quality perovskite film layer on the fiber substrate after some innovative changes are made to the fabrication processes. The power conversion efficiency of the finally obtained fiber‐shaped perovskite solar cell reaches 10.79%, which is currently the highest power conversion efficiency in the field of fiber‐shaped solar cells.

Organic-inorganic halide perovskites have been widely used in photovoltaic technologies. Despite tremendous progress in their efficiency and stability, perovskite solar cells (PSCs) are still facing the challenges of upscaling and stability for practical applications. As a mature film preparation technology, magnetron sputtering has been widely used to prepare metals, metallic oxides, and some semiconductor films, which has great application potential in the fabrication of PSCs. Here, a unique technology where high-quality perovskite films are prepared via magnetron sputtering for controllable composition, solvent-free, large-area, and massive production, is presented. This strategy transforms the perovskite materials from powder to thin films by magnetron sputtering and post-treatment (vapor-assisted treatment with methanaminium iodide gas and methylamine gas treatment), which is greatly favorable to manufacture tandem solar cells. The power conversion efficiency (PCE) of PSCs with perovskite films fabricated by magnetron sputtering is 6.14%. After optimization, high-performance perovskite films with excellent electronic properties are obtained and stable PSCs with excellent reproducibility are realized, showing a PCE of up to 15.22%. The entirely novel synthetic approach opens up a new and promising way to achieve high-throughput magnetron sputtering for large-area production in commercial applications of planar heterojunction and tandem PSCs.

Nickel oxide (NiO x ) is widely used as a promising hole transport material for perovskite solar cells (PSCs). A high concentration of Ni 3+ in the NiO x film is generally beneficial for charge transport of the PSCs; however, chemical redox reactions between surface Ni 3+ and perovskite materials result in decomposition of perovskite materials, which causes carrier recombination and impedes charge transport at the perovskite−NiO x interface. Herein, we employ magnetron sputtering to fabricate NiO x thin films with adjustable Ni 3+ concentrations to optimize the hole-transporting properties. A thin layer of phenylethylamine iodide (PEAI) is further introduced to reduce the detrimental Ni 3+ at the surface of NiO x , which eliminates the formation of undesirable defects and chemical species when in contact with the perovskite layer, leading to a dramatic increase in the power conversion efficiency (PCE) from 16.37 to 20.01%, which is one of the best performance using sputtered charge transport layers. The unencapsulated devices retain 88% of their initial PCE after storage in a nitrogen atmosphere for 1000 h under light. We further perform solar cell capacitance simulator (SCAPS) simulation to understand the effects of bulk and interfacial charge transport on the performance of PSCs, which agree with our experimental results. This work not only highlights the double-edged sword effect of the Ni 3+ content on the performance and stability of PSCs but also demonstrates a simple yet effective strategy to avoid the undesirable reaction between Ni 3+ and perovskite materials in the fabrication of PSCs with sputter-deposited NiO x .