Wani Aadil Fayaz, Khandy Shakeel Ahmad, Verma Ajay Singh, Dhiman Shobhna, Kaur Kulwinder
Department of Physics, Punjab Engineering College (Deemed to be University), Chandigarh, 160012, India.
Frontier Research Institute for Interdisciplinary Sciences, Islamic University of Science and Technology, Awantipora, Srinagar, J&K, 192122, India.
Sci Rep. 2024 Nov 28;14(1):29555. doi: 10.1038/s41598-024-81138-y.
In recent years, Silicene has attracted great interest in various fields but does not fit well in the field of thermoelectrics due to the absence of electronic band gap. Nevertheless, hydrogenation of silicene (SiH) delocalize the free electrons and induces gap widening (2.19 eV), but its thermoelectric performance is still limited due to the larger band gap. Thermoelectric performance can be effectively improved using strain engineering, which allows modulation of crystal as well as electronic energy levels of a material. We studied the effect of biaxial tensile strain on structure, stability and thermoelectric properties of SiH monolayer. Taking clue regarding the stability from phonon dispersion, tensile strain upto 14% is incorporated and results are discussed. The distortion of crystal structure with strain manipulates the characteristics of electronic band structure such that there is an indirect to direct band gap transition along with decrease in band gap, effective mass and relaxation time of carriers. As a result, the Seebeck coefficient falls and attains minimum value at 14% strain while electrical conductivity and electronic thermal conductivity shows increasing trend and maximize at 14% strain. Another crucial consequence of strain is that tensile strain led to a considerable decrease in lattice thermal conductivity. At a strain of 14%, the lattice thermal conductivity at 700 K (0.28) decreased by approximately 43% compared to its unstrained counterpart (0.49 K), which is highly beneficial for achieving high ZT. To assess the efficiency of thermoelectric conversion, the ZT is computed, revealing an increase from 1.66 in the unstrained state to 2.83 at a strain of 14% and a temperature of 700 K. The calculations unveil a nearly twofold increase in ZT with the implementation of strain engineering, underscoring its effectiveness in augmenting the efficiency of thermoelectric devices.
近年来，硅烯在各个领域引起了极大的关注，但由于缺乏电子带隙，它在热电领域的表现并不理想。然而，硅烯氢化（SiH）会使自由电子离域并导致带隙变宽（2.19电子伏特），但其热电性能仍因带隙较大而受限。使用应变工程可以有效提高热电性能，应变工程能够调节材料的晶体以及电子能级。我们研究了双轴拉伸应变对SiH单层结构、稳定性和热电性能的影响。从声子色散获取有关稳定性的线索，引入高达14%的拉伸应变并讨论结果。晶体结构随应变的畸变操控着电子能带结构的特性，使得出现从间接带隙到直接带隙的转变，同时带隙、载流子有效质量和弛豫时间减小。结果，塞贝克系数下降并在14%应变时达到最小值，而电导率和电子热导率呈上升趋势并在14%应变时达到最大值。应变的另一个关键影响是拉伸应变导致晶格热导率显著降低。在14%应变下，700K时的晶格热导率（0.28）与其无应变对应物（0.49W/mK）相比降低了约43%，这对实现高ZT非常有利。为了评估热电转换效率，计算了ZT值，结果表明从无应变状态下的1.66增加到14%应变和700K温度下的2.83。计算结果表明，通过实施应变工程，ZT值几乎增加了两倍，突出了其在提高热电装置效率方面的有效性。
