Light-management potential of dual-function n-SiOx in the top junction of micromorph solar cells with different front electrodes

• n-SiOx as advanced n-layer in the top cell of micromorph devices is investigated.
• The impact of the interface roughness is presented.
• Enhancement of both top cell current and total current is achieved.
• Guidelines for the cross-optimization of texture and n-SiOx layer are provided.

The optical performance of micromorph solar cells employing mixed-phase n-SiOx as advanced n-layer in the top junction has been systematically investigated with efficient state of the art ZnO front electrodes characterized by different scattering properties. The layer is applied with the dual function of n-layer and intermediate reflector. Enhanced top cell current complemented by significant dependence on the front texture has been observed. With smoother (locally flat-like) front electrode, interference effects are present with adverse impact on the spectral response of the bottom cell. Moving to rougher substrates these effects are strongly attenuated thus fully disclosing the strength of the present scheme, which is the simultaneous enhancement of both top cell current and total current. Quantitatively the gain is impacted by the front electrode morphology. Guidelines for a cross-optimization of texture and dual-function n-SiOx properties/thickness are supplied in order to take full advantage from this design.