Xiao Mei-Xia, Shao Xiao, Song Hai-Yang, Li Zhao, An Min-Rong, He Cheng
School of Materials Science and Engineering, Xi'an Shiyou University, Xi'an 710065, China.
Phys Chem Chem Phys. 2021 Aug 4;23(30):16023-16032. doi: 10.1039/d1cp01582f.
The effects of small organic molecule (SOM) adsorption with benzene (C6H6), hexafluorobenzene (C6F6), and p-difluorobenzene (C6H4F2) on the electronic properties of stanene under external electric fields are investigated through first-principles calculations. Different adsorption sites and molecular orientations are considered to determine the most stable configurations of small organic molecule (SOM) adsorption on the surface of stanene. The results show that the internal electric field caused by the adsorption of small organic molecules destroys the symmetry of the two sublattices of stanene in C6H6/stanene, C6F6/stanene and C6H4F2/stanene systems with the most stable configurations, opening the band gaps of stanene with 39.5, 18.9 and 14.5 meV, respectively. Under an external electric field, a wide range of linearly tunable and sizable direct band gaps (31.6-420.1 meV for the C6H6/stanene system, 14.8-587.2 meV for the C6F6/stanene system and 14.5-490.2 meV for the C6H4F2/stanene system) are merely determined by the strength of the composite electric field despite its direction. The mechanism of charge transfer between stanene and organic molecules under an external electric field can be revealed using an equivalent capacitor model to explain the tunable charge transfer. More importantly, the high carrier mobility of the stable SOM/stanene systems under an external electric field is largely retained due to the weak interactions at the interface. These results indicate that the electronic properties of stanene can be effectively modulated by the surface adsorption of organic molecules under an external electric field, providing effective and reversible routes to enhance the performance of stanene for novel electronic devices in the future.
通过第一性原理计算，研究了小分子有机物（SOM）与苯（C6H6）、六氟苯（C6F6）和对二氟苯（C6H4F2）吸附对外部电场下锡烯电子性质的影响。考虑了不同的吸附位点和分子取向，以确定小分子有机物（SOM）在锡烯表面吸附的最稳定构型。结果表明，在具有最稳定构型的C6H6/锡烯、C6F6/锡烯和C6H4F2/锡烯体系中，小分子有机物吸附引起的内电场破坏了锡烯两个子晶格的对称性，分别使锡烯的带隙打开39.5、18.9和14.5毫电子伏特。在外部电场下，尽管复合电场方向不同，但仅由其强度就可确定很宽范围内的线性可调且可观的直接带隙（C6H6/锡烯体系为31.6 - 420.1毫电子伏特，C6F6/锡烯体系为14.8 - 587.2毫电子伏特，C6H4F2/锡烯体系为14.5 - 490.2毫电子伏特）。利用等效电容器模型可以揭示外部电场下锡烯与有机分子之间的电荷转移机制，以解释可调电荷转移。更重要的是，由于界面处的弱相互作用，外部电场下稳定的SOM/锡烯体系的高载流子迁移率在很大程度上得以保留。这些结果表明，外部电场下有机分子的表面吸附可以有效调节锡烯的电子性质，为未来新型电子器件中增强锡烯性能提供了有效且可逆的途径。
