Xin Baojuan, Zou Kaixin, Liu Dayong, Li Boyan, Dong Hong, Cheng Yahui, Liu Hui, Zou Liang-Jian, Luo Feng, Lu Feng, Wang Wei-Hua
Department of Electronic Science and Engineering, and Tianjin Key Laboratory of Efficient Utilization of Solar Energy, Nankai University, Tianjin 300350, China.
Department of Physics, School of Sciences, Nantong University, Nantong 226019, China.
Phys Chem Chem Phys. 2024 Mar 20;26(12):9687-9696. doi: 10.1039/d3cp05913h.
Twisted bilayer graphene (tBLG) with C vacancies would greatly improve the density of states (DOS) around the Fermi level () and quantum capacitance; however, the single-band tight-binding model only considering p orbitals cannot accurately capture the low-energy physics of tBLG with C vacancies. In this work, a three-band tight-binding model containing three p orbitals of C atoms is proposed to explore the modulation mechanism of C vacancies on the DOS and quantum capacitance of tBLG. We first obtain the hopping integral parameters of the three-band tight-binding model, and then explore the electronic structures and the quantum capacitance of tBLG at a twisting angle of = 1.47° under different C vacancy concentrations. The impurity states contributed by C atoms with dangling bonds located around the and the interlayer hopping interaction could induce band splitting of the impurity states. Therefore, compared with the quantum capacitance of pristine tBLG (∼18.82 μF cm) at zero bias, the quantum capacitance is improved to ∼172.76 μF cm at zero bias, and the working window with relatively large quantum capacitance in the low-voltage range is broadened in tBLG with C vacancies due to the enhanced DOS around the . Moreover, the quantum capacitance of tBLG is further increased at zero bias with an increase of the C vacancy concentration induced by more impurity states. These findings not only provide a suitable multi-band tight-binding model to describe tBLG with C vacancies but also offer theoretical insight for designing electrode candidates for low-power consumption devices with improved quantum capacitance.
具有C空位的扭曲双层石墨烯（tBLG）将极大地提高费米能级（）附近的态密度（DOS）和量子电容；然而，仅考虑p轨道的单带紧束缚模型无法准确捕捉具有C空位的tBLG的低能物理特性。在这项工作中，提出了一个包含C原子三个p轨道的三带紧束缚模型，以探索C空位对tBLG的DOS和量子电容的调制机制。我们首先获得三带紧束缚模型的跳跃积分参数，然后研究在不同C空位浓度下，扭曲角 = 1.47°时tBLG的电子结构和量子电容。具有悬空键的C原子贡献的杂质态位于 和 附近，层间跳跃相互作用会导致杂质态的能带分裂。因此，与零偏压下原始tBLG的量子电容（约18.82 μF/cm）相比，具有C空位的tBLG在零偏压下的量子电容提高到约172.76 μF/cm，并且由于 附近DOS的增强，在低电压范围内具有相对大量子电容的工作窗口变宽。此外，随着C空位浓度的增加，由于更多杂质态的出现，tBLG在零偏压下的量子电容进一步增加。这些发现不仅提供了一个合适的多带紧束缚模型来描述具有C空位的tBLG，而且为设计具有改进量子电容的低功耗器件的电极候选材料提供了理论见解。
