Affiliation:
1. Qingdao Industrial Energy Storage Research Institute Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences Qingdao 266101 P. R. China
2. Shandong Energy Institute Qingdao 266101 P. R. China
3. Qingdao New Energy Shandong Laboratory Qingdao 266101 P. R. China
4. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 P. R. China
Abstract
AbstractKesterites, Cu2ZnSn(SxSe1−x)4 (CZTSSe), solar cells suffer from severe open‐circuit voltage (VOC) loss due to the numerous secondary phases and defects. The prevailing notion attributes this issue to Sn‐loss during the selenization. However, this work unveils that, instead of Sn‐loss, elemental inhomogeneity caused by Cu‐directional diffusion toward Mo(S,Se)2 layer is the critical factor in the formation of secondary phases and defects. This diffusion decreases the Cu/(Zn+Sn) ratio to 53% at the bottom fine‐grain layer, increasing the Sn‐/Zn‐related bulk defects. By suppressing the Cu‐directional diffusion with a blocking layer, the crystal quality is effectively improved and the defect density is reduced, leading to a remarkable photovoltaic coversion efficiency (PCE) of 14.9% with a VOC of 576 mV and a certified efficiency of 14.6%. The findings provide insights into element inhomogeneity, holding significant potential to advance the development of CZTSSe solar cells.
Funder
National Natural Science Foundation of China
Cited by
17 articles.
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