| 초록 |
A solar cell is an electrical device that converts the light energy into electricity. One of the crucial parts of realizing high-performance thin-film-based solar cells is an n-type buffer layer and CdS has been widely used as a magical material for various types of absorbers. In order to increase the environmental compatibility of such solar cells, however, a device without hazardous Cd should be developed. In this regard, we investigated the possibility of Zn(O,S) as an alternative buffer layer. Zn(O,S) thin films were grown by atomic layer deposition (ALD). ALD has been highlighted as an ideal method for forming very conformal and ultrathin films on various nanostructured devices and this technique is well suited for the pinhole-free formation of buffer layers. First, structural, electrical, chemical, and optical properties of Zn(O,S) thin films were studied. This new buffer layer was applied for earth-abundant Cu2ZnSn(S,Se)4 solar cells and the highest power-conversion efficiency of ~2.7% was achieved by optimizing O/S ratio. The detailed analysis on how O/S ratio influences the device performance will be presented. |
