真空快速退火对CIGS太阳能电池性能的影响

Effect of Vacuum Rapid Annealing Treatment on Performance of CIGS Solar Cells

采用溅射后硒化法制备CIGS电池吸收层,并在此基础上制备具有glass/Mo/CIGS/Cd S/i-ZnO/ZnO:Al/Ni-Al结构的CIGS电池。实验研究了真空退火对电池性能的影响。通过优化退火条件,电池光电转换效率从4.91%提高到14.01%。进一步研究发现,退火有助于改善部分单层薄膜的性能,但是其对电池性能的提升主要来自来于:1)退火促使Cd2+扩散进入CIGS表面取代VCu,钝化浅能级缺陷的同时形成n-CIGS,使p-n结进入CIGS层内部,从而大幅减少了界面复合中心;2)退火使得CIGS表面吸附的H2O分子脱附,提高了CIGS电学和带隙均匀性,从而改善电池的均匀性,电池性能得到全面提升。

CIGS absorber layers were prepared by sequential sputtering/selenization method. Based on that, CIGS solar cells were fabricated with a structure of glass/Mo/CIGS/CdS/i-ZnO/ZnO：Al/Ni-Al grid. The influences of an- nealing treatment on the performance of CIGS solar cells were investigated. By optimizing annealing condition, the cell efficiency increased from 4.91% to 14.01%. Further investigation revealed that the post-annealing treatment had two advantages. Firstly, it facilitated the diffusion of Cd ions into CIGS surface to substitute the Cu vacancies. Thus, the surface of CIGS converted from p-type to n-type conduction, leading to the shift of p-n junction from CIGS/CdS interface into the CIGS layer. Therefore, the recombination centers at the p-n junction were greatly reduced. Secondly, most H2O molecules being adsorbed on the CIGS surface were eliminated by annealing, which improved the uniformity of electrical properties and band-gap of CIGS layer, resulting better performance of CIGS solar cell.