Li嵌入对V2O5电子结构及光学性质的影响

采用第一性原理局域密度近似法计算了V₂O₅的电子态密度和能带结构以及Li嵌入后对其电子结构和光学性质的影响。计算结果表明,V₂O₅是间接带隙半导体,Li的嵌入并没有改变其电子的跃迁方式。但Li的嵌入使得V₂O₅导带能量下移,禁带宽度减小,导带中原有的劈裂被分裂的能级填满;同时致使价带出现展宽。电子态密度计算结果表明Li的嵌入对临近的O和V的电子结构有较大的影响。Li2s电子的注入提高了V₂O₅的费米能级并导致其进入导带。由于价带中的电子只能跃迁到费米能级以上的导带空能级,这致使体系实际的光学带隙增大。同时随着Li注入量的进一步增加,价带的展宽更为明显,费米能级亦呈升高的趋势,使得光学带隙随着Li注入量的增加而增大。

Influence of Intercalated Li on Electronic Structures and Optical Properties of V2O5

The density of states and band structures of α-V2O5 and Li-intercalated V2O5 (LixV2O5, x= 0.5 and 1.0) have been studied using a first-principles calculation based on density function theory with the local density approximation. The results indicate that V2O5 is an indirect-gap semiconductor; the intercalation of Li will not change its way of electron transition. While, the intercalation of Li lowers the energy of conduction band, and then narrows the band gap. At the same time, due to the intercalation of Li, the split-off in the conduction band of V2O5 disappears because of the split of conduction band. The Fermi level of LixV2O5 increases dramatically due to the electron transfer from Li 2s to the V2O5 host, which is probably the main reason why the optical band-gap augments with the Li intercalation.