High efficiency CZTSSe solar cells enabled by dual Ag-passivation approach via aqueous solution process

Ag substitution in Cu2ZnSn(S,Se)4 (CZTSSe) is a promising way to mitigate Cu/Zn related defects, electro-static fluctuations and Shockley-Read-Hall (SRH) recombination centers. However, high performance ACZTSSe solar cells are generally demonstrated with more Ag amounts and strenuous fabrication pro-cesses, which are not ideal when using cheap constituent materials CZTSSe. To reduce the Ag amount (2%-3%), local Ag substitutions into CZTSSe at front (F), back (B) and dual front/back (FB) were proposed. Experimental results revealed that F-passivation effectively reduced the Cu/Zn related defects and further limits the interface/bulk recombination whereas B-passivation improved the grain growth at the back interface and further allows enhanced transport of charge carriers. By employing the dual Ag-passivation approach, the final ACZTSSe device parameters were significantly improved and remarkable power conversion efficiency (PCE) of 12.43% was achieved with eco-friendly aqueous solution process.(c) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.