Bifacial Cu(In,Ga)Se2 solar cells with submicron absorber thickness: back-contact passivation and light management

For bifacial Cu(In,Ga)Se
₂
solar cells with submicron absorber thickness, an Al
₂
O
₃
-layer deposited by a simple, self-organized spray-pyrolysis process onto the transparent SnO
₂
:F back-contact is used to increase open circuit voltage and thereby increase power conversion efficiency, especially for rear-illumination, indicating reduced charge carrier back-contact recombination. On non-passivated SnO
₂
:F, a thin (10nm) Mo-layer improved the electrical back-contact properties, while on Al
₂
O
₃
-passivated SnO
₂
:F, the solar cell performance was higher without Mo-modification. However, even with Mo-modification, the solar cell performance increased for Al
₂
O
₃
-passivated compared to non-passivated back-contacts demonstrating the benefit of the Al
₂
O
₃
-layer for bifacial solar cells with submicron Cu(In,Ga)Se
₂
absorber layers.