Structural and Optoelectronic Characterization of (Agx Cu1-x) ZnSnSe4 solid solution

As the open-circuit voltage in CZTSSe devices is believed to be limited by absorber band tailing caused by the exceptionally high density of Cu/Zn disorder, replacing of Cu with Ag this density is predicted to drop. In this study, neutron diffraction and diffuse reflectance were applied to evaluate the crystal structure and optoelectronic properties of the (Ag
_1-x
Cu
_x
)
₂
ZnSnSe
₄
solid solution (ACZTSe). The results allow us to suggest that in spite of both end members of the solid solution being reported to crystallize in kesterite type structure, at least (Ag
_1-x
Cu
_x
)
₂
ZnSnSe4 with x=0.17 and 0.46 crystallize in the stannite type structure and thus block Cu/Zn disorder.