Tin-based perovskites are promising alternative materials to address the toxicity problems of lead-based perovskites. However, compared with mature lead-based perovskites, the poor stability and low photoluminescence quantum yield (PLQY) of tin-based perovskites seriously hamper their practical application.

Liang Li, Shanghai Jiao Tong University, China, and colleagues have developed a simple strategy to synthesize highly efficient and stable all-inorganic lead-free Cs₄SnBr₆–SnF₂ perovskites with SnF₂ as the tin(II) source. The team used SnF₂, CsBr, and NH₄Br as precursors to prepare the desired perovskites by wet ball milling with ultrapure water.

The introduction of SnF₂ suppresses the oxidation of Sn²⁺ during the synthesis of the perovskite, and the Sn–F bonds formed improve its stability. The Cs₄SnBr₆–SnF₂ perovskite achieved a significant boost in PLQY from 2.8 % to 62.8 % compared with SnBr₂-derived Cs₄SnBr₆ crystals. The SnF₂-derived Cs₄SnBr₆ demonstrated high stability against oxygen, moisture, and light irradiation over the course of 1,200 hours. Using the perovskite as a green-light emitter, a white light-emitting diode (WLED) device was constructed with a high color rendering index (CRI) value of 96 % and a long-term operational stability of 1,000 hours.

• Stable Lead‐free Tin Halide Perovskite with Operational Stability >1200 h by Suppressing Tin(II) Oxidation,
  Qinggang Zhang, Shiqiang Liu, Mengda He, Weilin Zheng, Qun Wan, Mingming Liu, Xinrong Liao, Wenji Zhan, Changwei Yuan, Jinyu Liu, Haijiao Xie, Xiaojun Guo, Long Kong, Liang Li,
  Angew. Chem. Int. Ed. 2022.
  https://doi.org/10.1002/anie.202205463