基于光子晶体异质结的高效太阳能电池反射器研究

设计了一种可用于太阳能电池反射器的二维三角晶格光子晶体异质结结构.采用传输矩阵法对该结构在可见至近红外波长范围入射电磁波的反射率进行了模拟计算,并比较了不同入射方向下反射率的变化.结果表明,光线垂直入射时,该结构光子晶体对近红外波段入射光可实现完全反射|随着偏转角度的增大,在整个可见-近红外波段均显示出极高的反射特性.该结构有望用于制作覆盖整个可见光-近红外波段的高效全方位反射器.     

First-principles study of the effects of selected interstitial atoms on the generalized stacking fault energies,strength, and ductility of Ni

We analyze the influences of interstitial atoms on the generalized stacking fault energy （GSFE）, strength, and ductility of Ni by first-principles calculations. Surface energies and GSFE curves are calculated for the （112） （111） and / 101） （ 1 1 1） systems. Because of the anisotropy of the single crystal, the addition of interstitials tends to promote the strength of Ni by slipping along the （10T） direction while facilitating plastic deformation by slipping along the （115） direction. There is a different impact on the mechanical behavior of Ni when the interstitials are located in the slip plane. The evaluation of the Rice criterion reveals that the addition of the interstitials H and O increases the brittleness in Ni and promotes the probability of cleavage fracture, while the addition of S and N tends to increase the ductility. Besides, P, H, and S have a negligible effect on the deformation tendency in Ni, while the tendency of partial dislocation is more prominent with the addition of N and O. The addition of interstitial atoms tends to increase the high-energy barrier γmax, thereby the second partial resulting from the dislocation tends to reside and move on to the next layer.     

Detection of finger interruptions in silicon solar cells using photoluminescence imaging

Finger interruptions are common problems in screen printed solar cells, resulting in poor performance in efficiency because of high effective series resistance. Electroluminescence(EL) imaging is typically used to identify interrupted fingers. In this paper, we demonstrate an alternative method based on photoluminescence(PL) imaging to identify local series resistance defects, with a particular focus on finger interruptions. Ability to detect finger interruptions by using PL imaging under current extraction is analyzed and verified. The influences of external bias control and illumination intensity on PL images are then studied in detail. Finally, in comparison with EL imaging, the using of PL imaging to identify finger interruptions possesses the prominent advantages: in PL images, regions affected by interrupted fingers show higher luminescence intensity, while regions affected by recombination defects show lower luminescence intensity. This inverse signal contrast allows PL imaging to more accurately identify the defect types.     

Ag吸附对MgF_2表面结构稳定性及光学性能的影响

基于密度泛函理论,对Ag在MgF2低指数表面(100)面、(001)面、(110)面的吸附行为及吸附机理进行分析,并研究了吸附对体系结构稳定性及光学性能的影响。结果表明:Ag在MgF2表面的吸附为稳定的化学吸附,在(100)面、(001)面、(110)面的最佳吸附位分别为最外层F的四重穴位、短桥位、长桥位;吸附机理主要表现为Ag与附近F的共价键作用。吸附Ag后,MgF2表面稳定性增加,稳定性顺序由吸附前的(001)(100)(110),变为吸附后的(100)(110)(001)。在300 nm到1000 nm波段,MgF2(100)面、(001)面吸附Ag体系,折射率实部较吸附前减小。     

Tensile properties of phase interfaces in Mg–Li alloy：A first principles study

Employing density functional theory, we study the tensile and fracture processes of the phase interfaces in Mg–Li binary alloy. The simulation presents the strain–stress relationships, the ideal tensile strengths, and the fracture processes of three phase interfaces. The results show that the α/α and α/β interfaces have larger tensile strength than that of β/β interface. The fractures of both α/α and β/β interfaces are ductile fractures, while the α/β fractures abruptly._Further analyses show that the fracture of the α/β occurs at the interface.     

基于光子晶体异质结的高效太阳能电池反射器研究

设计了一种可用于太阳能电池反射器的二维三角晶格光子晶体异质结结构.采用传输矩阵法对该结构在可见至近红外波长范围入射电磁波的反射率进行了模拟计算,并比较了不同入射方向下反射率的变化.结果表明,光线垂直入射时,该结构光子晶体对近红外波段入射光可实现完全反射;随着偏转角度的增大,在整个可见-近红外波段均显示出极高的反射特性.该结构有望用于制作覆盖整个可见光-近红外波段的高效全方位反射器.     

可见光波段SiO2/CdSe一维光子晶体及缺陷模的研究究

采用SiO2/CdSe构建了可见光波段一维光子晶体结构,并在其中引入LiTaO3缺陷层。利用传输矩阵法,分析了电磁波在无缺陷与含LiTaO3缺陷层两种光子晶体中的带隙结构,系统地研究了缺陷层参数对光子晶体可见光波段带隙结构的影响规律。计算结果表明：LiTaO3的引入,有利于带隙宽度的增加,调整缺陷层结构参数,缺陷模的位置可在不同颜色区域出现,如红光、黄光等缺陷模。该结构有望用于制作可见光波段的滤波器。     

Si中离子注入S杂质引起的深能级研究

本文在n型硅中通过离子注入方法用500 keV的能量注入剂量为1×1014cm-2的过量S以引入杂质,并通过深能级瞬态谱方法(DLTS)对离子注入引入的深能级进行研究,得到多个S的深能级峰,计算了各深能级的位置和其俘获截面等参数。同时也发现,采用离子注入工艺在Si中引入了大量缺陷深能级。     

Ti掺杂SnO2 半导体固溶体的第一性原理研究

Ti掺杂SnO2固溶体是钛基氧化物耐酸阳极的重要组成部分. 采用基于密度泛函理论的第一性原理对Sn1-xTixO2(x=0, 1/12, 1/8, 1/6, 1/4, 1/2, 3/4, 5/6)固溶体的电子结构进行计算, 分析了能带结构、 电子态密度和电荷密度以及晶格参数的变化. 结果表明, Ti掺入SnO2晶格后, 其晶格参数随组分增加近似呈直线降低, Ti-O键的共价性强于Sn-O键. 掺杂后带隙仍为直接带隙, 且随着掺杂比例的增加, 带隙逐渐减小. 当掺杂比例x=0.5时, 形成能达到最低值(-6.11 eV), 固溶体最稳定. 本文的计算结果为钛基氧化物电极材料的研究与开发提供了一定的理论依据.