| 초록 |
The kesterite Cu2ZnSnSe4 (CZTSe) material has been attracting great attention because it consists of earth-abundant and nontoxic elements. CZTSe solar cells, however, show lower power conversion efficiency than its counterpart, like Cu(In,Ga)(S,Se)2 (CIGS)solar cells and CdTe, due to high open-circuit voltage (Voc) deficit. High Voc deficit in CZTSe solar cells may be caused by large potential fluctuations, band tailing effect, point defects, surface recombination, and etc. Especially, the Sn related point defects (such as ZnSn or SnZn) known as deep-level defects act as a recombination center for mobile charge carriers, resulting in Voc loss. To overcome this problem, Ge is incorporated into the CZTSe film in order to cure the Sn related defects, and it forms Cu2Zn(Ge1-xSnx)Se4 (CZGTSe) phase. The CZGTSe films are prepared by sputtering and post-annealing process, and analyzed by X-ray diffraction and scanning electron microscopy. Afterward, Ge incorporated CZTSe solar cells are characterized to investigate the influence of [Ge]/[Sn] ratio on Voc. |
