Yan Tong-Tong, Zhou Guo-Xiang, Jiang Xiao-Long, Qin Xu-Chen, Li Jia
School of Science, Hebei University of Technology, Tianjin 300401, China.
College of Science, Civil Aviation University of China, Tianjin 300300, China.
Phys Chem Chem Phys. 2024 Sep 18;26(36):23998-24007. doi: 10.1039/d4cp02590c.
Janus TiPX (X = F, Cl, and Br) monolayers were systematically investigated through first-principles calculations. The Janus TiPX monolayers exhibit mechanical and dynamic stability. Two monolayers are indirect bandgap semiconductors, except the TiPBr monolayer, which has the features of a quasi-direct bandgap semiconductor. Biaxial strain can modify the band gap of single layers. The Janus TiPX monolayers have remarkable flexibility and piezoelectric properties. In particular, the TiPF monolayer shows high horizontal (44.18 pm V) and vertical piezoelectric coefficients (-3.59 pm V). These values exceed those of conventional bulk materials, like GaN (3.1 pm V) and α-quartz (2.3 pm V). All of the monolayers have absorption coefficients of 10 cm for visible and ultraviolet (UV) light, which are one order of magnitude greater than that of MoSSe. Furthermore, TiPX monolayers have high carrier mobility. Janus TiPX monolayers represent a class of two-dimensional (2D) materials with exceptional properties and multifunctionality, holding significant promise for various applications in piezoelectric sensors, solar cells, and nano-electronic devices.
通过第一性原理计算系统地研究了Janus TiPX（X = F、Cl和Br）单层。Janus TiPX单层表现出机械和动态稳定性。除了具有准直接带隙半导体特征的TiPBr单层外，另外两个单层是间接带隙半导体。双轴应变可以改变单层的带隙。Janus TiPX单层具有显著的柔韧性和压电性能。特别是，TiPF单层显示出高的横向（44.18 pm V）和纵向压电系数（-3.59 pm V）。这些值超过了传统体材料，如GaN（3.1 pm V）和α-石英（2.3 pm V）。所有单层对于可见光和紫外光的吸收系数均为10 cm，这比MoSSe的吸收系数大一个数量级。此外，TiPX单层具有高载流子迁移率。Janus TiPX单层代表了一类具有优异性能和多功能性的二维（2D）材料，在压电传感器、太阳能电池和纳米电子器件等各种应用中具有巨大的潜力。
