Significantly Improving the Crystal Growth of a Cu2ZnSn(S,Se)4 Absorber Layer by Air-Annealing a Cu2ZnSnS4 Precursor Thin Film

Xinan Shi; Yuxiang Wang; Hui Yu; Gang Wang; Lijian Huang; Daocheng Pan

doi:10.1021/acsami.0c12630

Significantly Improving the Crystal Growth of a Cu₂ZnSn(S,Se)₄ Absorber Layer by Air-Annealing a Cu₂ZnSnS₄ Precursor Thin Film

ACS Appl Mater Interfaces. 2020 Sep 16;12(37):41590-41595. doi: 10.1021/acsami.0c12630. Epub 2020 Sep 1.

Authors

Xinan Shi^{1

2}, Yuxiang Wang^{1

2}, Hui Yu^{1

2}, Gang Wang^{1

2}, Lijian Huang^{1

2}, Daocheng Pan^{1

2}

Affiliations

¹ State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, China.
² University of Science and Technology of China, Hefei, Anhui 230026, China.

PMID: 32814424
DOI: 10.1021/acsami.0c12630

Abstract

The crystal quality of a Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film is crucially important to a high-performance CZTSSe solar cell. After selenization, a bilayer CZTSSe thin film consisting of a large-grain top layer and a small-particle bottom layer is usually observed according to the literature. In this work, a facile air-annealing pretreatment is conducted for a Cu₂ZnSnS₄ precursor thin film prior to selenization, which can lead to sodium diffusion into the CZTS precursor thin film and surface oxidization of the CZTS thin film. Our experimental results revealed that the Na prediffusion and the surface oxidation of the CZTS precursor thin film can significantly promote the crystal growth of the CZTSSe thin film, which can completely remove the small-particle bottom layer and form a large-grain-spanned CZTSSe thin film. As a result, a photoelectric conversion efficiency of 9.80% was achieved by this method.

Keywords: air-annealing; kesterite; sodium diffusion; surface oxidation; thin-film solar cells.