Perspectives of the Kesterite Cu₂ZnSnS₄ Based Photovoltaics

Kesterite absorber materials Cu₂ZnSnS₄ (CZTS) are attractive candidates for abundant, non-toxic and highly efficient photovoltaics. The photovoltaic research community is looking forward to a breakthrough in the kesterite solar cell device efficiency that has reached 13%, which has turned out to be difficult to outperform. Hereby, we present recent advancements in the development of kesterite CZTS based kesterite monograin layer (MGL) solar cells, with the focus on p-n junction interface modifications. We present two-step combined etching and thermal treatment process for the improvement of the CZTS/CdS interface with the detailed recombination and elemental diffusion processes analysis. Significantly reduced series resistance of the CZTS MGL solar cells was achieved, enabling record device efficiency of the corresponding devices reaching close to 12%.<br/>Secondly, the influence of the Ge doping of the Cu₂ZnSn(S,Se₄) (CZTSSe) kesterite monograins’ surface via gas phase treatments as well as solution doping in order to modify the defect structure of the kesterite absorber surface to the solar cell device performance is introduced. We present detailed analysis of the related charge carriers recombination processes analysis.<br/>Finally, the perspectives and possible routes of the absorber/buffer interface modification for further improvement of the kesterite based device efficiency is discussed.