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

For bifacial Cu(In,Ga)Se₂ solar cells with submicron absorber thickness, an Al₂O₃-layer deposited by a simple, self-organized spray-pyrolysis process onto the transparent SnO₂: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 SnO₂:F, a thin (10nm) Mo-layer improved the electrical back-contact properties, while on Al₂O₃-passivated SnO₂:F, the solar cell performance was higher without Mo-modification. However, even with Mo-modification, the solar cell performance increased for Al₂O₃-passivated compared to non-passivated back-contacts demonstrating the benefit of the Al₂O₃-layer for bifacial solar cells with submicron Cu(In,Ga)Se₂ absorber layers.