Two-dimensional (2D) ternary materials have gained significant attention because of their additional degree of freedom stemming from the variable stoichiometry. However, the research on 2D ternary materials is still in the early stage because of the difficulty of synthesizing them. Here, ultrathin PbSnS₂ flakes are synthesized via chemical vapor deposition (CVD) assisted by salt and a molecular sieve with thickness down to ∼2.4 nm. Adding salt and a molecular sieve results in lowering of the melting point of metal precursors and uniformly distributed source vapors in the reaction system, respectively. Impressively, 2D PbSnS₂ flake shows giant anisotropic mobility (μ_armchair/μ_zigzag = 1.78) and responsivity (R_zigzag/R_armchair = 1.25). The employment of salt and a molecular sieve in the CVD process for successful synthesis of ultrathin PbSnS₂ flakes may provide a new platform for the design of other 2D ternary materials.

二维（2D）三元材料由于其可变的化学计量而具有额外的自由度，因此受到了广泛的关注。然而，由于难以合成二维三元材料，因此其研究仍处于早期阶段。在这里，超薄的PbSnS ₂薄片是通过化学气相沉积（CVD）在盐和分子筛的辅助下合成的，其厚度低至约2.4 nm。添加盐和分子筛分别降低了金属前体的熔点和反应体系中均匀分布的源蒸气。令人印象深刻的是，二维PbSnS ₂薄片显示出巨大的各向异性迁移率（μ_扶手椅/ μ_之字形 = 1.78）和响应度（R_之字形/ R_扶手椅 = 1.25）。为成功合成超薄PbSnS ₂薄片，在CVD工艺中使用盐和分子筛可能为设计其他2D三元材料提供了新的平台。