采用低成本溶胶凝胶旋涂法制备了不同Mg含量的Zn1-xMgxO薄膜, 用其代替传统化学水浴法制备的CdS作为铜铟镓硒 (Cu(In,Ga)Se2, CIGS) 薄膜太阳电池的缓冲层材料.用X射线衍射仪、原子力显微镜、紫外可见吸收光谱和X射线光电子能谱仪等研究了Mg掺杂量对Zn1-xMgxO薄膜的结构、形貌、光学性能及Zn1-xMgxO/CIGS异质结之间能带排列的影响.结果表明: 所制备的Zn1-xMgxO薄膜均为非晶结构; 随着Mg掺入量的增加, Zn1-xMgxO薄膜的表面形貌由条纹状变为六方形纳米颗粒, 表面粗糙度由23.53 nm减小到1.14 nm; 光学带隙值由3.55 eV增大到3.62 eV; Zn1-xMgxO/CIGS之间的导带偏移值由+0.68 eV减小到-0.33 eV, 导带排列由“尖峰状”变为“悬崖状”; 当配制的溶液中Mg源和Zn源的摩尔比为0.1时, 所制备的Zn0.82Mg0.18O/CIGS之间的导带偏移值为+0.22 eV, 电池效率最高, 达5.83%.

Zn1-xMgxO thin films have been prepared by sol-gel spin-coating technique instead of the CdS buffer layers synthesized by conventional chemical bath deposition for Cu(In,Ga)Se2 (CIGS) solar cells. The effects of Mg doping amount on the structural, morphological, optical properties of Zn1-xMgxO films and band alignment of Zn1-xMgxO/CIGS are investigated by X-ray diffraction, Atmoic force microscope, UV-vis-NIR spectroscopy and X-ray photoelectron spectroscopy. The results show that these properties changed with the increase of Mg. All the films are amorphous. The surface morphology changes from stripe to hexagon nanoparticles and the surface roughness decreases from 23.53 nm to 1.14 nm. The optical band gap increases from 3.55 eV to 3.62 eV and conduction band offsets changes from +0.68 eV to -0.33 eV. Accordingly, the band alignment of Zn1-xMgxO/CIGS changes from “spike-like” to “cliff-like”. An efficiency of up to 5.83% is achieved for a CIGS solar cell with a Zn1-xMgxO (using a molar ratio 0.1 of the Mg source and the Zn source in the precusor solution) buffer layer, which is attributed to the optimized conduction band offset of +0.22 eV at the Zn1-xMgxO/CIGS interface.