The Stone–Wales (SW) defects have a critical impact on the physical properties of the carbon-based materials with pentagonal and hexagonal rings, which also emerge in other pentagon-based materials with the Cairo tessellation. However, scarce attention has been paid to SW defect engineering in two-dimensional (2D) pentagonal materials. In the present letter, we propose four unreported 2D PdSSe monolayers (designated as SW1–SW4) by introducing SW defects into the penta-PdSSe monolayer. The electronic structure, optical, electrical transport, and thermal transport properties of these SW defect structures have been systematically investigated based on first-principles calculations. SW1–SW4 retain the square-planar coordination as presented in the pristine penta-PdSSe, exhibiting excellent dynamical, thermal, and mechanical stability. Particularly, SW1 and SW2 exhibit direct bandgaps, which are more favorable for electronic transitions. The suitable band alignments meet the requirement of photocatalytic water splitting. Furthermore, the defect structures show high visible-light absorption coefficients (∼105 cm−1) and ultra-high carrier mobility (∼103 cm2V−1s−1). More excitingly, these defect structures display ultra-low anisotropic lattice thermal conductivities (lower than 2 Wm−1K−1 at room temperature). The suitable bandgap values, appropriate band edge positions, good optical absorption performances, and ultra-high carrier mobility concomitant with ultra-low lattice thermal conductivity render these PdSSe monolayers with SW defect structures as promising semiconductor materials for potential applications in nanoelectronics, optoelectronics, solar cell, photocatalyst, and thermoelectric energy conversions.

中文翻译：

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在具有完全 Stone-Wales 缺陷的 PdSSe 单层中具有超高载流子迁移率和超低晶格热导率


Stone-Wales （SW） 缺陷对具有五边形和六边形环的碳基材料的物理性能有关键影响，这也出现在其他带有开罗镶嵌的五边形材料中。然而，对二维 （2D） 五边形材料中的 SW 缺陷工程的关注很少。在本信中，我们通过将 SW 缺陷引入 penta-PdSSe 单层，提出了四种未报道的 2D PdSSe 单层（指定为 SW1-SW4）。基于第一性原理计算，系统研究了这些 SW 缺陷结构的电子结构、光学、电传输和热传输特性。SW1-SW4 保留了原始 penta-PdSSe 中呈现的方形平面配位，表现出优异的动力学、热和机械稳定性。特别是，SW1 和 SW2 表现出直接带隙，这更有利于电子跃迁。合适的波段对准满足光催化分解水的要求。此外，缺陷结构显示出高可见光吸收系数 （∼105 cm-1） 和超高载流子迁移率 （∼103 cm2V-1s-1）。更令人兴奋的是，这些缺陷结构显示出超低的各向异性晶格热导率（在室温下低于 2 Wm-1K-1）。合适的带隙值、适当的带边缘位置、良好的光吸收性能以及伴随着超低晶格热导率的超高载流子迁移率，使这些具有 SW 缺陷结构的 PdSSe 单分子层成为有前途的半导体材料，可用于纳米电子学、光电子学、太阳能电池、光催化剂和热电能转换。