Institute of Electro-Optical Science and Technology, National Taiwan Normal University, No. 88, Sec. 4, Ting-Chou Rd., Taipei 11677, Taiwan.
Phys Chem Chem Phys. 2013 Nov 7;15(41):18174-8. doi: 10.1039/c3cp53310g.
The CIGS solar cell is one of the most promising photovoltaic devices due to the achievement of the highest conversion efficiency (>20%) among all thin-film solar cells. The CIGS cell has a glass/Mo/CIGS/CdS/TCO configuration, and the CIGS-Mo interface is a Schottky barrier to holes. During the sulfurization-after-selenization (SAS) CIGS formation process with H2Se gas, the Mo surface transforms naturally into MoSe2 at the CIGS-Mo interface. In this work, the electrical impact of MoSe2 on CIGS solar cells was investigated. Different CIGS-Mo interfaces were prepared with two CIGS processes. One is SAS, and the other is the sequential-sputtering-selenization CIGS process with Se gas. Formation of MoSe2 is hardly observed in the latter process. Samples were characterized by XRD, the van der Pauw method, reflectance, and visual inspection. Besides, Schottky barrier heights of cells were extracted from J-V-T measurements. For the first time, it was experimentally shown that the existence of thin MoSe2 film can decrease the apparent Schottky barrier height of CIGS solar cells. In addition, 1-dimensional numerical simulation showed that a larger barrier height affects both the fill factor and open-circuit voltage. Therefore, the formation of MoSe2 during the CIGS process should minimize the negative effect of Schottky barrier on solar-cell performances, especially with large Schottky barrier.
铜铟镓硒（CIGS）太阳能电池是最有前途的光伏器件之一，因为它在所有薄膜太阳能电池中实现了最高的转换效率（>20%）。CIGS 电池具有玻璃/Mo/CIGS/CdS/TCO 的结构，CIGS-Mo 界面是空穴的肖特基势垒。在使用 H2Se 气体的硒化硫（SAS）CIGS 形成过程中，Mo 表面在 CIGS-Mo 界面自然转化为 MoSe2。在这项工作中，研究了 MoSe2 对 CIGS 太阳能电池的电影响。使用两种 CIGS 工艺制备了不同的 CIGS-Mo 界面。一种是 SAS，另一种是使用 Se 气体的顺序溅射硒化 CIGS 工艺。在后一种工艺中几乎观察不到 MoSe2 的形成。通过 XRD、范德堡法、反射率和目视检查对样品进行了表征。此外，还从 J-V-T 测量中提取了电池的肖特基势垒高度。这是首次实验表明，薄 MoSe2 膜的存在可以降低 CIGS 太阳能电池的表观肖特基势垒高度。此外，一维数值模拟表明，较大的势垒高度会影响填充因子和开路电压。因此，在 CIGS 工艺中形成的 MoSe2 应尽量减小肖特基势垒对太阳能电池性能的负面影响，特别是在具有较大肖特基势垒的情况下。
