Engineering of Interface and Bulk Properties in Cu2ZnSn(S,Se)4 Thin-Film Solar Cells with Ultrathin CuAlO2 Intermediate Layer and Ge Doping

Kuldeep Gour, Vijay Karade, Minwoo Lee, Jun Sung Jang, Eunae Jo, Pravin Tukaram Babar, Hongjae Shim, Jae Sung Yun, Jongsung Park, Jin Hyeok Kim

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Recently, kesterite-based absorbers and related compounds have been considered as promising eco-friendly light absorber materials for thin-film solar cells (TFSCs). However, the device performances of kesterite-based TFSCs are limited because of the formation of defects and poor interfacial properties. In this study, we developed a strategic approach to improve the device performances of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells using back-interface passivation of the absorber layer and further reduced the formation of defects through Ge doping. The application of CuAlO2 (CAO) as an intermediate layer near the back interface efficiently improves the grain growth and minimizes the detrimental Mo(S,Se)2 thickness. In addition, the Ge nanolayer deposited over the CAO layer improves the absorber bulk quality, effectively suppresses the defect density, and reduces the nonradiative carrier recombination losses. As a result, the short-circuit current density, fill factor, and power conversion efficiency of the champion device with the CAO and Ge nanolayer improved from 31.91 to 36.26 mA/cm2, 0.55 to 0.61, and 8.58 to 11.01%, respectively. This study demonstrates a potential approach to improve the performances of CZTSSe TFSCs using a combination of back-interface passivation and doping.
Original languageEnglish (US)
JournalACS Applied Energy Materials
DOIs
StatePublished - Feb 7 2022

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