Platinum-based transition metal dichalcogenides have been gaining renewed interest because of the development of a new method to synthesize thin film structures. Here, using first-principles calculation, we explore the electronic properties of PtX₂ (X = S, Se, and Te) with respect to film thickness. For bulk and layered structures (1 to 10 layers), octahedral 1T is the most stable. Surprisingly, we also find that the 3R structure has comparable stability relative to the 1T, implying possible synthesis of 3R. For a bulk 1T structure, PtS₂ is semiconducting with an indirect band gap of 0.25 eV, while PtSe₂ and PtTe₂ are both semi-metallic. Still, all their corresponding monolayers exhibit an indirect semiconducting phase with band gaps of 1.68, 1.18, and 0.40 eV for PtS₂, PtSe₂, and PtTe₂, respectively. For the band properties, we observe that all these materials manifest decreasing/closing of indirect band gap with increasing thickness, a consequence of quantum confinement and interlayer interaction. Moreover, we discover that controlling the thickness and applying strain can manipulate van Hove singularity resulting to high density of states at the maximum valence band. Our results exhibit the sensitivity and tunability of electronic properties of PtX₂, paving a new path for future potential applications.

由于开发了一种合成薄膜结构的新方法，基于铂的过渡金属二硫化二氢化合物引起了人们的新兴趣。在这里，使用第一性原理计算，我们探索了PtX ₂（X = S，Se和Te）相对于膜厚度的电子特性。对于块状和分层结构（1到10层），八面体1T是最稳定的。出人意料的是，我们还发现3R结构相对于1T具有相当的稳定性，这意味着可能合成3R。对于块状1T结构，PtS ₂是半导体，其间接带隙为0.25 eV，而PtSe ₂和PtTe ₂都是半金属的。尽管如此，所有它们相应的单层仍表现出间接半导体相，其PtS ₂，PtSe ₂和PtTe _2的带隙分别为1.68、1.18和0.40 eV 。对于带的性质，我们观察到所有这些材料都表现出随着厚度的增加，间接带隙的减小/闭合，这是量子限制和层间相互作用的结果。此外，我们发现控制厚度和施加应变可以操纵van Hove奇异性，从而导致在最大价带处具有高密度的状态。我们的结果展示了PtX ₂电子性能的灵敏度和可调性，为将来的潜在应用铺平了新道路。