CAS Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences , Guangzhou 510640, People's Republic of China.
ACS Appl Mater Interfaces. 2013 Nov 13;5(21):10605-13. doi: 10.1021/am402502a. Epub 2013 Oct 31.
Tetragonal CuInS2 (CIS) has been successfully deposited onto mesoporous TiO2 films by in-sequence growth of InxS and CuyS via a successive ionic layer absorption and reaction (SILAR) process and postdeposition annealing in sulfur ambiance. X-ray diffraction and Raman measurements showed that the obtained tetragonal CIS consisted of a chalcopyrite phase and Cu-Au ordering, which related with the antisite defect states. For a fixed Cu-S deposition cycle, an interface layer of β-In2S3 formed at the TiO2/CIS interface with suitable excess deposition of In-S. In the meantime, the content of the Cu-Au ordering phase decreased to a reasonable level. These facts resulted in the retardance of electron recombination in the cells, which is proposed to be dominated by electron transfer from the conduction band of TiO2 to the unoccupied defect states in CIS via exponentially distributed surface states. As a result, a relatively high efficiency of ~0.92% (V(oc) = 0.35 V, J(sc) = 8.49 mA cm(-2), and FF = 0.31) has been obtained. Last, but not least, with an overloading of the sensitizers, a decrease in the interface area between the sensitized TiO2 and electrolytes resulted in deceleration of hole extraction from CIS to the electrolytes, leading to a decrease in the fill factor of the solar cells. It is indicated that the unoccupied states in CIS with energy levels below EF0 of the TiO2 films play an important role in the interface electron recombination at low potentials and has a great influence on the fill factor of the solar cells.
四方相 CuInS2（CIS）通过顺序生长 InxS 和 CuyS 成功地沉积在介孔 TiO2 薄膜上，这是通过连续离子层吸收和反应（SILAR）过程和在硫气氛中的后沉积退火实现的。X 射线衍射和拉曼测量表明，所获得的四方 CIS 由黄铜矿相和 Cu-Au 有序组成，这与反位缺陷态有关。对于固定的 Cu-S 沉积循环，在 TiO2/CIS 界面处形成β-In2S3 的界面层，具有适当过量的 In-S 沉积。同时，Cu-Au 有序相的含量降低到合理水平。这些事实导致电池中的电子复合延迟，这被认为是通过指数分布的表面态，电子从 TiO2 的导带转移到 CIS 中的未占据缺陷态来主导的。结果，获得了相对较高的效率约 0.92%（Voc = 0.35 V，Jsc = 8.49 mA cm-2，FF = 0.31）。最后但并非最不重要的是，敏化剂的过加载导致敏化 TiO2 和电解质之间的界面面积减小，从而减缓了 CIS 中的空穴从电解质中的提取，导致太阳能电池的填充因子降低。这表明 TiO2 薄膜 EF0 以下能级的 CIS 中的未占据态在低电位下的界面电子复合中起着重要作用，并对太阳能电池的填充因子有很大影响。
