三角形硒、碲链中显著的二次谐波产生和体光伏效应
Significant Second-Harmonic Generation and Bulk Photovoltaic Effect in Trigonal Selenium and Tellurium Chains
摘要：
一维的硒和碲以螺旋链状结构结晶，因此表现出迷人的性质。通过第一性原理计算，我们研究了一维Se和Te的线性和非线性光学（NLO）性质，发现这两个体系都表现出明显的NLO响应。特别是，1D Se被发现具有大的二次谐波产生系数是高达7倍以上的GAN，甚至是几倍以上的大块对应物。另一方面，1D Te也产生显著的NLO敏感性，其超过体GAN的5倍。此外，一维Te具有显著的线性电光系数rxxx（0）。特别是，Te链表现出大的移位电流响应，最大值是从BaTiO 3获得的最大光伏响应的2倍。因此，一维Se和Te在太阳能转换、电光开关等方面具有潜在的应用前景。最后，一维Se和Te的强非线性光学效应归因于它们的高各向异性、强共价键和孤对电子的一维结构。这些结果将有助于进一步的实验研究和寻找具有大非线性光学效应的优良材料。
英文摘要：
One-dimensional selenium and tellurium crystalize in helical chainlike structures and thus exhibit fascinating properties. By performing first-principles calculations, we have researched the linear and nonlinear optical (NLO) properties of 1D Se and Te, and find that both systems exhibit pronounced NLO responses. In particular, 1D Se is found to possess large second-harmonic generation coefficient being up to 7 times larger than that of GaN, and even is several times larger than that of the bulk counterpart. On the other hand, 1D Te also produces significant NLO susceptibility which exceeds the bulk GaN by 5 times. Furthermore, 1D Te is shown to possess prominent linear electro-optic coefficient rxxx(0). Particularly, Te chain exhibits large shift current response and the maximum is more than the maximal photovoltaic responses obtained from BaTiO3 by 2 times. Therefore, 1D Se and Te may find potential applications in solar energy conversion, electro-optical switches, and so on. Finally, much stronger NLO effects of 1D Se and Te are attributed to their one-dimensional structures with high anisotropy, strong covalent bonding and lone-pair electrons. These findings will contribute to the further study in experiments and search for excellent materials with large NLO effects.
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