Experimental and theoretical study on band gap tuning of Cu2ZnSn(S1−xSex)4 absorbers for thin-film solar cells

A non-hydrazine solution followed by spin-coating has been used to produce Cu
₂
ZnSnS
₄
(CZTS) precursor. After annealed with sulfur or selenium powders in tube furnace at 530°C, Cu
₂
ZnSn(S
_1-x
Se
_x
)
₄
(CZTSSe) thin films were obtained. Both theoretical calculation and experimental results showed that band gap can be tuned from 1.48 to 1.04eV by replacing S with Se in CZTSSe. Solar cell devices were fabricated using nominally CZTS and CZTSe absorbers with thickness around 500 nm. The device based on CZTSSe shows better performance than the CZTS device owing to the larger grain size and better electronic transport.