Summary The power conversion efficiency (PCE) of tin perovskite solar cells is impeded by the extremely poor resistance to oxidation and high density of intrinsic Sn vacancies. Herein, we grow a 2D-quasi-2D-3D Sn perovskite film using removable pseudohalogen NH 4 SCN as a structure regulator. This hierarchy structure remarkably enhances air stability resulting from the parallel growth of 2D PEA 2 SnI 4 as the surface layer. We then explore the hierarchy structure perovskite films in planar structural solar cells, which generate a PCE up to 9.41%. The device retains 90% of its initial performance for almost 600 hr. Our results suggest that adding removable NH 4 SCN in a perovskite precursor can significantly improve the stability and photovoltaic performance of Sn perovskite. This finding provides a powerful strategy to manipulate the structure of low-dimensional perovskite in order to enhance the performance of perovskite solar cells.
A novel BiOCl/Bi 5 O 7 I (BOC-BOI) heterojunction was prepared by growing ultrathin 2D BiOCl nanosheets in situ on the surface of 3D Bi 5 O 7 I microspheres . The 2D/3D heterostructure of BOC-BOI composites inhibited the agglomeration of BiOCl nanosheets, and benefited the multiple reflection and refraction of light, which greatly enhanced the absorption and utilization of light. The 50-BOC-BOI composite showed 97.7% degradation efficiency of rhodamine B (RhB) after 70 min Xe light irradiation. And its apparent degradation rate constant ( k ) was 0.0377 min −1 , being 4.9 and 15.1 times than that of pristine BiOCl (0.0077 min −1 ) and Bi 5 O 7 I (0.0025 min −1 ), respectively. The enhanced photocatalytic activity of BOC-BOI composites was attributed to stronger light capture ability, more abundant active sites and higher charge carrier separation efficiency, confirmed by UV-Vis DRS, SEM, TEM, BET, Zeta potential and electrochemical characterizations. The free radical capture experiments showed that the main active species in this system were holes (h + ) and superoxide free radicals (·O 2 − ). Combining the results of UV-Vis DRS and Mott-Schottky test, a reasonable type II heterojunction mechanism was proposed.
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