Phase stability of Cu2ZnSnS4-SnS2 interfaces: Cu2ZnSn3S8

Cu
₂
ZnSnS
₄
-based photovoltaics are often plagued by the presence of secondary phases. Unfortunately, the properties of some of these phases are poorly understood. For example the formation of a quaternary Cu
₂
ZnSn
₃
S
₈
phase has been reported. Unfortunately, there is only one published observation of this phase. This work demonstrates that Cu
₂
ZnSnS
₄
-SnS
₂
phase boundaries are remarkably stable and that Cu
₂
ZnSn
₃
S
₈
does not form under a wide variety of conditions. Thus, it is unlikely that this phase would be present in Cu
₂
ZnSnS
₄
-based photovoltaic devices. Cu
₄
Sn
₇
S
₁₆
, however, seems stable with respect to SnS
₂
and Cu
₂
ZnSnS
₄
and merits further study.