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Rare-earth-doped TiO2 rutile as a promising ferromagnetic alloy for visible light absorption in solar cells: first principle insights
RSC Advances ( IF 3.9 ) Pub Date : 2020-9-25 , DOI: 10.1039/d0ra05725h
A Fakhim Lamrani 1
Affiliation  

The electronic structure and magneto-optic properties of TiO2 (rutile) doped with two concentrations of rare-earth (RE) elements are explored using a first-principle all-electron full-potential augmented spherical-wave method based on the PBEsol–GGA approximation, to examine their potential use as a spintronic and optoelectronic system. The results predict that all compounds exhibit half-metallic character, the only exception is by doping with Nd or that the material is magnetic but the cloud is still a half-metallic magnet. We also found that the localized level at the Fermi energy shifts to lower energy as the atomic number of the 4f-element increases. Consequently, the mechanism that controls the ferromagnetism in these systems has been proposed according to this positioning. The energy of the localized level due to Gd is sufficiently low to lie at the top of the valence band, while Eu produces a midgap state. However, the Fermi level was not noticed precisely at the middle of the energy gap. In contrast, the impurity states of the Nd-, Pm-, and Sm-dopants are close to the bottom of the conduction band of the host system. This allows electrons to be delocalized, and gives a higher scattering cross-section. Interestingly, the analysis of optical absorption and electrical conductivity emphasizes that this ferromagnetic DMS based on rare-earth elements has the power to be a promising spintronic device for visible light absorption in solar cells. Finally, the relationship between the mechanism that controls the ferromagnetism and the absorption efficiency of visible light is discussed.

中文翻译:

稀土掺杂的 TiO2 金红石作为一种有前途的铁磁合金,可用于太阳能电池中的可见光吸收:第一原理见解

TiO 2的电子结构和磁光性质使用基于 PBEsol-GGA 近似的第一原理全电子全电势增强球面波方法探索掺杂两种浓度稀土 (RE) 元素的(金红石),以检查它们作为自旋电子和光电系统。结果预测,所有化合物都表现出半金属特性,唯一的例外是掺杂 Nd 或材料具有磁性但云仍然是半金属磁体。我们还发现,随着 4f 元素的原子序数增加,费米能量的局域能级转移到较低的能量。因此,根据这一定位提出了控制这些系统中铁磁性的机制。由于 Gd 引起的局域能级能量低到足以位于价带的顶部,而 Eu 产生一个中间间隙状态。然而,费米能级并没有被精确地注意到在能隙的中间。相反,Nd-、Pm-和Sm-掺杂剂的杂质态接近主体系统的导带底部。这允许电子离域,并提供更高的散射截面。有趣的是,对光吸收和电导率的分析强调,这种基于稀土元素的铁磁 DMS 有能力成为太阳能电池中可见光吸收的有前途的自旋电子器件。最后,讨论了控制铁磁性的机制与可见光吸收效率之间的关系。和 Sm 掺杂剂接近主体系统的导带底部。这允许电子离域,并提供更高的散射截面。有趣的是,对光吸收和电导率的分析强调,这种基于稀土元素的铁磁 DMS 有能力成为太阳能电池中可见光吸收的有前途的自旋电子器件。最后,讨论了控制铁磁性的机制与可见光吸收效率之间的关系。和 Sm 掺杂剂接近主体系统的导带底部。这允许电子离域,并提供更高的散射截面。有趣的是,对光吸收和电导率的分析强调,这种基于稀土元素的铁磁 DMS 有能力成为太阳能电池中可见光吸收的有前途的自旋电子器件。最后,讨论了控制铁磁性的机制与可见光吸收效率之间的关系。对光吸收和电导率的分析强调,这种基于稀土元素的铁磁DMS有能力成为太阳能电池中可见光吸收的有前途的自旋电子器件。最后,讨论了控制铁磁性的机制与可见光吸收效率之间的关系。对光吸收和电导率的分析强调,这种基于稀土元素的铁磁DMS有能力成为太阳能电池中可见光吸收的有前途的自旋电子器件。最后,讨论了控制铁磁性的机制与可见光吸收效率之间的关系。
更新日期:2020-09-25
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