Lv Xiaoyu, Zheng Zilong, Zhao Ming, Wang Hanpeng, Zhuang Daming
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Materials (Basel). 2023 Mar 31;16(7):2806. doi: 10.3390/ma16072806.
Tandem solar cells usually use a wide band gap absorber for top cell. The band gap of CuInGaSe can be changed from 1.04 eV to 1.68 eV with the ratio of Ga/(In+Ga) from 0 to 1. When the ratio of Ga/(In+Ga) is over 0.7, the band gap of CIGS absorber is over 1.48 eV. CIGS absorber with a high Ga content is a possible candidate one for the top cell. In this work, CuInGa precursors were prepared by magnetron sputtering with CuIn and CuGa targets, and CIGS absorbers were prepared by selenization annealing. The Ga/(In+Ga) is changed by changing the thickness of CuIn and CuGa layers. Additionally, CIGS solar cells were prepared using CdS buffer layer. The effects of Ga content on CIGS thin film and CIGS solar cell were studied. The band gap was measured by PL and EQE. The results show that using structure of CuIn/CuGa precursors can make the band gap of CIGS present a gradient band gap, which can obtain a high open circuit voltage and high short circuit current of the device. With the decrease in Ga content, the efficiency of the solar cell increases gradually. Additionally, the highest efficiency of the CIGS solar cells is 11.58% when the ratio of Ga/(In+Ga) is 0.72. The value of Voc is 702 mV. CIGS with high Ga content shows a great potential for the top cell of the tandem solar cell.
串联太阳能电池通常在顶部电池使用宽带隙吸收体。CuInGaSe的带隙可随着Ga/(In + Ga)的比例从0到1而从1.04电子伏特变化到1.68电子伏特。当Ga/(In + Ga)的比例超过0.7时，CIGS吸收体的带隙超过1.48电子伏特。具有高Ga含量的CIGS吸收体是顶部电池的一个可能候选材料。在这项工作中，通过用CuIn和CuGa靶磁控溅射制备CuInGa前驱体，并通过硒化退火制备CIGS吸收体。通过改变CuIn和CuGa层的厚度来改变Ga/(In + Ga)。此外，使用CdS缓冲层制备CIGS太阳能电池。研究了Ga含量对CIGS薄膜和CIGS太阳能电池的影响。通过光致发光（PL）和外量子效率（EQE）测量带隙。结果表明，使用CuIn/CuGa前驱体结构可使CIGS的带隙呈现梯度带隙，这可以获得器件的高开路电压和高短路电流。随着Ga含量的降低，太阳能电池的效率逐渐增加。此外，当Ga/(In + Ga)的比例为0.72时，CIGS太阳能电池的最高效率为11.58%。开路电压（Voc）值为702毫伏。具有高Ga含量的CIGS在串联太阳能电池的顶部电池方面显示出巨大潜力。
