He Chuan, Zhao Qiyi, Huang Yuanyuan, Du Wanyi, Zhu Lipeng, Zhou Yixuan, Zhang Sujuan, Xu Xinlong
Shaanxi Joint Lab of Graphene, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & Photon-Technology, Northwest University, Xi'an 710069, China.
Phys Chem Chem Phys. 2020 Oct 7;22(37):21428-21435. doi: 10.1039/d0cp03968c. Epub 2020 Sep 18.
Tunable optical properties play an important role in the high performance of optoelectronic applications based on two-dimensional (2D) transition metal carbide and nitride (MXene) materials. Herein, the optical properties of functionalized MXene monolayers ScCT (T = O and OH) are investigated by strain engineering. The strain-dependent linear optical properties of ScCT possess broadband optical response due to the geometry and orbital overlap effect. The peaks from the second-order nonlinear coefficient elements d (d, d, and d) at around half the band-gap exhibit a redshift for ScCO (blueshift for ScC(OH)) with the increase of strain. The strain-dependent d reveals that ScCO with -1268 pm V % has a larger photoelastic coefficient than that of ScC(OH) with -574 pm V % at 1% strain. Meanwhile, the photoelastic tensors can not only be increased but also reduced with the increase of strain due to the dispersion relation. Moreover, the azimuthal angle-dependent second harmonic generation (SHG) from strained ScCT monolayers depends highly on the strained states and the pumping photon energy. The results pave the way for the tunable, broadband, and anisotropic applications of nonlinear optoelectronic devices based on MXenes based on strain engineering.
可调谐光学特性在基于二维（2D）过渡金属碳化物和氮化物（MXene）材料的光电子应用的高性能中起着重要作用。在此，通过应变工程研究了功能化MXene单层ScCT（T = O和OH）的光学特性。由于几何结构和轨道重叠效应，ScCT的应变相关线性光学特性具有宽带光学响应。在带隙约一半处，二阶非线性系数元素d（d、d和d）的峰值随着应变增加，ScCO出现红移（ScC(OH)出现蓝移）。应变相关的d表明，在1%应变下，具有-1268 pm V⁻¹的ScCO比具有-574 pm V⁻¹的ScC(OH)具有更大的光弹性系数。同时，由于色散关系，光弹性张量会随着应变增加而增大或减小。此外，应变ScCT单层的方位角相关二次谐波产生（SHG）高度依赖于应变状态和泵浦光子能量。这些结果为基于应变工程的基于MXene的非线性光电器件的可调谐、宽带和各向异性应用铺平了道路。
