High-efficiency micromorph solar cell with light management in tunnel recombination junction

• Light management was realized in tunnel recombination junction of micromorph solar cell.
• Evolutionary tunnel recombination junction also demonstrated a low contact series resistance.
• Initial efficiency of a-Si: H/μc-Si: H tandem solar cells is reached to 13.65%.

Effective tunnel recombination junctions (TRJs) are crucial to achieve high conversion efficiencies in hydrogenated amorphous/ microcrystalline silicon (a-Si:H/μc-Si:H) micromorph solar cells. In conventional TRJs, the n-μc-Si:H layer is used to form an ohmic contact between the n- and p-type layers, which introduces additional absorption loss in the TRJs. Here we demonstrated an effective TRJ without using the n-μc-Si:H layer in a-Si:H/μc-Si:H micromorph solar cells, which we denote as an evolutionary TRJ. In comparison to the conventional n-μc-SiOx:H/n-μc-Si:H/p-nc-SiOx:H TRJs, the evolutionary structure reduces the parasitic absorption and thus significantly increases the short-circuit current density (JSC) of the bottom cell. A high initial efficiency of 13.65% has been achieved for the a-Si:H/μc-Si:H micromorph solar cells deposited on the as-grown metal organic chemical vapor deposited ZnO:B substrates.