High-Performance Tin–Lead Mixed-Perovskite Solar Cells with Vertical Compositional Gradient

Jiupeng Cao, Hok Leung Loi, Yang Xu, Xuyun Guo, Naixiang Wang, Chun ki Liu, Tianyue Wang, Haiyang Cheng, Ye Zhu, Mitch Guijun Li, Wai Yeung Wong, Feng Yan (Corresponding Author)

Research output: Journal article publicationJournal articleAcademic researchpeer-review

89 Citations (Scopus)


Sn–Pb mixed perovskites with bandgaps in the range of 1.1–1.4 eV are ideal candidates for single-junction solar cells to approach the Shockley–Queisser limit. However, the efficiency and stability of Sn–Pb mixed-perovskite solar cells (PSCs) still lag far behind those of Pb-based counterparts due to the easy oxidation of Sn2+. Here, a reducing agent 4-hydrazinobenzoic acid is introduced as an additive along with SnF2 to suppress the oxidation of Sn2+. Meanwhile, a vertical Pb/Sn compositional gradient is formed spontaneously after an antisolvent treatment due to different solubility and crystallization kinetics of Sn- and Pb-based perovskites and it can be finely tuned by controlling the antisolvent temperature. Because the band structure of a perovskite is dependent on its composition, graded vertical heterojunctions are constructed in the perovskite films with a compositional gradient, which can enhance photocarrier separation and suppress carrier recombination in the resultant PSCs. Under optimal fabrication conditions, the Sn–Pb mixed PSCs show power conversion efficiency up to 22% along with excellent stability during light soaking.

Original languageEnglish
Article number2107729
JournalAdvanced Materials
Issue number6
Publication statusPublished - 10 Feb 2022


  • compositional gradients
  • heterojunctions
  • perovskite solar cells
  • Sn–Pb mixed perovskite

ASJC Scopus subject areas

  • General Materials Science
  • Mechanics of Materials
  • Mechanical Engineering


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