Optimizing folded silicon thin-film solar cells on ZnO honeycomb electrodes involves fabricating zinc oxide honeycomb structures using nanosphere lithography and electrochemical deposition. Simulations show that while electrical performance is unaffected by periodicity, increasing honeycomb diameter reduces short-circuit current density due to parasitic absorption in the zinc oxide. For micromorph tandem solar cells with a microcrystalline silicon intrinsic layer over 500nm thick, the honeycomb structure creates a focusing effect greatly enhancing the quantum efficiency of the bottom microcrystalline solar cell.

1. OPTIMIZING FOLDED SILICON THIN-FILM SOLAR CELLS ON
ZNO HONEYCOMB ELECTRODES
ABSTRACT
A promising approach for low-cost nanostructured thin-film solar cells with enhanced
absorption is the fabrication of zinc oxide (ZnO) honeycomb electrodes in a combined bottomup
process of nanosphere lithography and electrochemical deposition. To optimize the honeycomb
structures, we investigate thin hydrogenated amorphous silicon (a-Si:H) solar cells (with 100 nm
absorber thickness) on honeycomb electrodes with different periodicities in optical and electrical
simulations;whereas the electrical performance is not significantly affected with changing
periodicity, the short-circuit current density is reduced for increasing honeycomb diameter due to
increased parasitic absorption of the electrochemically deposited ZnO. Furthermore, we
demonstrate that for micromorph tandem solar cells with an intrinsic layer thickness of
hydrogenated microcrystalline silicon (μc-Si:H) of >500 nm, a focusing effect occurs, which
leads to a strong enhancement in the quantum efficiency in the microcrystalline bottom solar cell.