Hou Na, Fang Xiao-Hui
Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
Inorg Chem. 2022 Jul 18;61(28):10756-10767. doi: 10.1021/acs.inorgchem.2c00970. Epub 2022 Jul 6.
The electronic and nonlinear optical (NLO) properties of BN-substituted graphynes and the corresponding alkali-doped hybrid systems have been determined using density functional theory. When the carbon atoms in the graphyne are replaced by BN pairs, the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap () increases to some extent, and the static first hyperpolarizabilities (β) of the novel systems hardly increase. However, when an alkali atom is introduced on the surface of BN-substituted graphyne, the doping effect can effectively modulate the electronic and NLO properties. Doping the alkali atom can significantly narrow the wide of BN-substituted graphynes in the range of 1.03-2.03 eV. Furthermore, the doping effect brings considerable β values to these alkali-doped systems, which are 52-3609 au for Li-doped systems and 3258-211 053 au for Na/K-doped ones. The result reveals that the β values of alkali-doped complexes are influenced by the atomic number of alkali metals and the proportion of BN pairs. The nature of the excellent NLO responses of alkali-doped complexes can be understood by the low excitation energy of the crucial excited state and the analysis of the first hyperpolarizability density. Besides, these alkali-doped complexes have a deep-ultraviolet working region. Therefore, the combined effect of alkali metal doping and BN substitution can be an excellent strategy to design novel high-performance NLO materials based on graphyne.
采用密度泛函理论确定了硼氮取代的石墨炔及其相应的碱掺杂杂化体系的电子和非线性光学（NLO）性质。当石墨炔中的碳原子被硼氮对取代时，最高占据分子轨道-最低未占据分子轨道（HOMO-LUMO）能隙（）有所增加，而新型体系的静态第一超极化率（β）几乎没有增加。然而，当在硼氮取代的石墨炔表面引入碱原子时，掺杂效应可以有效地调节电子和NLO性质。掺杂碱原子可以显著缩小硼氮取代石墨炔在1.03 - 2.03 eV范围内的宽能隙。此外，掺杂效应给这些碱掺杂体系带来了可观的β值，锂掺杂体系为52 - 3609原子单位，钠/钾掺杂体系为3258 - 211053原子单位。结果表明，碱掺杂配合物的β值受碱金属原子序数和硼氮对比例的影响。通过关键激发态的低激发能和第一超极化率密度分析，可以理解碱掺杂配合物优异NLO响应的本质。此外，这些碱掺杂配合物具有深紫外工作区域。因此，碱金属掺杂和硼氮取代的联合效应可以成为设计基于石墨炔的新型高性能NLO材料的优秀策略。
