Performance Enhancement in Powder-Fabricated Cu 2 (ZnSn)Se 4 Solar Cell by Roll Compression

• Published in: Materials Vol. 16; no. 3
• Main Authors: Park, Jaehyun, Nam, Hyobin, Song, Bong-Geun, Burak, Darya, Jang, Ho Seong, Lee, Seung Yong, Cho, So-Hye, Park, Jong-Ku
• Format: Journal Article
• Language: English
• Published: Switzerland 26.01.2023
• Subjects: densification; Cu1.7Zn1.2Sn1.0S4.0 (CZTS); Cu2ZnSnSe4 (CZTSe); light absorbing layer (or film); thin film solar cell; roll compression; selenization; powder process
• ISSN: 1996-1944; 1996-1944

Despite the improved conversion efficiency of Cu (ZnSn)Se (CZTSe) solar cells, their roll-to-roll fabrication nonetheless leads to low performance. The selenization time and temperature are typically considered major parameters for a powder-based CZTSe film; meanwhile, the importance of the densification during the roll-to-roll process is often overlooked. The densification process is related to the porosity of the light-absorbing layer, where high porosity lowers cell performance. In this study, we fabricated a dense CZTSe absorber layer as a method of controlling the compression of a powder precursor (Cu (Zn Sn )S (CZTS)) during the roll-press process. The increased particle packing density of the CZTS layer was crucial in sintering the powder layer into a dense film and preventing severe selenization of the Mo back electrode. The pressed absorber layer of the CZTSe solar cell exhibited a more uniform chemical composition determined using dynamic secondary ion mass spectrometry (SIMS). Under the AM 1.5G illumination condition, the power conversion efficiency of the pressed solar cell was 6.82%, while the unpressed one was 4.90%.