Increased $V_{\text{OC}}$ and FF in ZnO1-xSx-buffered CuIn1-xGaxSe2 Solar Cells by Cadmium Partial Electrolyte Treatment

We applied a Cd partial electrolyte treatment (Cd-PE) to condition the surface of CuIn
1-x
Ga
x
Se
2
(CIGS) layers for solar cells in combination with a ZnO
1-x
S
x
buffer by chemical bath deposition or sputtering. The treatment led to increased
$V_{\text{OC}}$
, FF, and efficiency. We find that a Cd-PE leads to an improved CIGS/buffer layer heterojunction quality in ZnO
1-x
S
x
-buffered devices. We use advanced characterization methods as well as simulations in order to further understand the mechanism.