改进了WS2-WSe2声子晶体的热电性能：第一性原理计算的见解,Nanoscale

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改进了WS2-WSe2声子晶体的热电性能：第一性原理计算的见解
Nanoscale ( IF 5.8 ) Pub Date : 2021-3-19 , DOI: 10.1039/d0nr09169c
Dan Han _{1,

2,

3,

4} , Xiaoheng Yang _{1,

2,

3,

4} , Mu Du _{2,

3,

4,

5} , Gongming Xin _{2,

3,

4,

6} , Jingchao Zhang _{7,

8,

9} , Xinyu Wang _{1,

2,

3,

4,

10} , Lin Cheng _{4,

11,

12}

Affiliation

近来，二维过渡金属二硫化二氢（TMDC）单层膜由于其优异的物理性能而备受关注。在本研究中，我们通过第一性原理计算系统地研究了不同WS ₂ -WSe ₂声子晶体的热电性质。首先，所有声子晶体的超晶格与热性质（SL1和SL2）和它们的各个组件（WS ₂和WSE ₂）进行评价，其中，晶格热导率（ķ _pH值WS的）₂和WSE ₂单层表现出各向同性行为，而SL1和SL2单层的值表现出弱的各向异性行为。可以看出，WS ₂和WSe ₂单层的k _ph值大于SL1和SL2单层的k _ph值，这可以归因于声子基团速度和声子寿命的降低。此外，我们计算了所有单层的电子能带结构，表明所有单层都是半导体。然后，评估不同温度下的电导率，塞贝克系数，功率因数，电子热导率和ZT值。WS ₂的ZT_最大值WSe_{如图2所示}，在1000 K时，具有p型掺杂的SL1和SL2单层分别为0.43、0.37、0.95和0.66。可以证明SL1单层具有最大的ZT，至少比WS的ZT高两倍。₂和WSe₂单层。最后，我们构建了两种带有周期性孔的声子晶体（PCH1和PCH2），并评估了其热电性能。可以观察到，PCH2结构显示出最佳的热电性能。PCH2结构的ZT_最大值可以沿着x和y掺杂p型掺杂，分别达到2.53和4.54方向，比SL1单层的方向高2.66倍和6.75倍。这项工作提供了一种获得更高热电性能的新策略，并演示了声子晶体在基于TMDC的纳米电子设备中的潜在应用。

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Improved thermoelectric properties of WS2–WSe2 phononic crystals: insights from first-principles calculations

Recently, two-dimensional transition metal dichalcogenide (TMDC) monolayers have attracted much attention owing to their excellent physical properties. In the present study, we systematically investigate the thermoelectric properties of different WS₂–WSe₂ phononic crystals by utilizing first-principles calculations. First, the thermal properties of all phononic crystals with superlattices (SL1 and SL2) and their individual components (WS₂ and WSe₂) are evaluated, in which the lattice thermal conductivities (k_ph) of WS₂ and WSe₂ monolayers present isotropic behaviors, while the values of SL1 and SL2 monolayers reveal weak anisotropic behaviors. It can be observed that the k_ph values of WS₂ and WSe₂ monolayers are larger than those of SL1 and SL2 monolayers, which can be attributed to the decreasing phonon group velocity and phonon lifetime. Moreover, we calculate the electronic band structures of all monolayers, indicating that all monolayers are semiconductors. Afterwards, the electrical conductivities, the Seebeck coefficients, the power factors, the electronic thermal conductivities, and the ZT values at different temperatures are evaluated. The ZT_max values of WS₂, WSe₂, SL1, and SL2 monolayers with p-type doping are 0.43, 0.37, 0.95, and 0.66 at 1000 K. It can be proved that the SL1 monolayer possesses the largest ZT, which is at least two times higher than those of the WS₂ and WSe₂ monolayer. Finally, we build two kinds of phononic crystals with periodic holes (PCH1 and PCH2) and evaluate the thermoelectric properties. It can be observed that the PCH2 structure shows the best thermoelectric performance. The ZT_max values of the PCH2 structure can reach 2.53 and 4.54 with p-type doping along the x and y directions, which are 2.66 and 6.75 times higher than those of the SL1 monolayer. This work provides a new strategy to obtain higher thermoelectric performance and demonstrates the potential applications of phononic crystals in TMDC-based nanoelectronic devices.

更新日期：2021-04-14

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