Chen Yanyan, Sun Jie, Kang Wei, Wang Qian
School of Materials Science and Engineering, Peking University, Beijing 100871, China.
Center for Applied Physics and Technology, HEPDS, College of Engineering, Peking University, Beijing 100871, China.
Materials (Basel). 2021 Sep 27;14(19):5604. doi: 10.3390/ma14195604.
The pentagon has been proven to be an important structural unit for carbon materials, leading to different physical and chemical properties from those of hexagon-based allotropes. Following the development from graphene to penta-graphene, a breakthrough has very recently been made for graphyne-for example, imidazole-graphyne (ID-GY) was formed by assembling experimentally synthesized pentagonal imidazole molecules and acetylenic linkers. In this work, we study the thermal properties and thermoelectric performance of ID-GY by combining first principle calculations with the Boltzmann transport theory. The calculated lattice thermal conductivity of ID-GY is 10.76 W/mK at 300 K, which is only one tenth of that of -graphyne (106.24 W/mK). A detailed analysis of the harmonic and anharmonic properties, including the phonon group velocity, phonon lifetime, atomic displacement parameter, and bond energy curves, reveals that the low lattice thermal conductivity can be attributed to the low Young's modulus, low Debye temperature, and high Grüneisen parameter. Furthermore, at room temperature, ID-GY can reach a high value of 0.46 with a 5.8 × 10 cm hole concentration, which is much higher than the value for many other carbon-based materials. This work demonstrates that changing structural units from hexagonal to pentagonal can significantly reduce the lattice thermal conductivity and enhance the thermoelectric performance of carbon-based materials.
五角形已被证明是碳材料的重要结构单元，这使得其物理和化学性质与基于六边形的同素异形体不同。随着从石墨烯到五边形石墨烯的发展，最近在石墨炔方面取得了突破——例如，咪唑石墨炔（ID-GY）是通过将实验合成的五角形咪唑分子和炔键连接体组装而成。在这项工作中，我们通过将第一性原理计算与玻尔兹曼输运理论相结合，研究了ID-GY的热性质和热电性能。计算得出，ID-GY在300 K时的晶格热导率为10.76 W/mK，仅为γ-石墨炔（106.24 W/mK）的十分之一。对包括声子群速度、声子寿命、原子位移参数和键能曲线在内的谐波和非谐波性质进行详细分析后发现，低晶格热导率可归因于低杨氏模量、低德拜温度和高格林艾森参数。此外，在室温下，ID-GY在空穴浓度为5.8×10 cm时可达到0.46的高值，这远高于许多其他碳基材料的值。这项工作表明，将结构单元从六边形变为五角形可以显著降低晶格热导率并提高碳基材料的热电性能。
