Eu掺杂量对锐钛矿相TiO_2电子寿命和吸收光谱影响的第一性原理研究

First-principles study on the doped concentration effect on electron lifespan and absorption spectrum of Eu-doping anatase TiO_2

采用基于密度泛函理论框架下的第一性原理平面波超软赝势方法,建立了不同Eu掺杂量的锐钛矿相TiO_2超胞模型,计算了其态密度、差分电荷密度、能带结构和吸收光谱.结果发现:掺杂后Eu在TiO_2的禁带中产生杂质能级.通过对比两种不同Eu掺杂量(1.39at%和2.08at%)下的锐钛矿TiO_2的能带结构,发现掺杂量越高,杂质能级越向深能级方向移动,说明电子复合率随杂质浓度增加而增加,即电子寿命变小,同时吸收光谱红移越显著,强度越强.根据实际需要,可在锐钛矿TiO_2中适量掺杂Eu,在适当减少电子寿命情况下,使吸收光谱红移.

Based on first principles within the density-functional theory,we establish three different concentration Eu-doping anatase TiO_2 models by using the plane-wave ultrasoft pseudopotential method.We calculate the density of states,the electron density difference, the band structure and the absorption spectrum.The results show that Eu creates an impurity level in the band gap of TiO_2 and a redshift in absorption spectrum of anatase TiO_2.By comparing the bands of anatase TiO_2,with two different Eu-doping concentrations （1.39 at%and 2.08 at%） we find that more Eu atoms make the impurity level deeper,the recombination rate bigger,and the electron lifespan shorter.