All-Vacuum-Deposited Bifacial Cu₂ZnSnSe₄ Photovoltaic Cells with Sputtered Cd-Free Buffer Layer

Figure 6

TEM images of the (a) 4-cycle specimen and (b) 1-cycle specimen; and HRTEM images of (c) region A1 in the 1-cycle specimen and (d) region A2 in the 1-cycle specimen.

(a)

(b)

(c)

(d)