Dopant‐Free Back‐Contacted Silicon Solar Cells with an Efficiency of 22.1%

Contact recombination at the interface between the selective contact material and electrode interface is one of the most pressing issues limiting most photovoltaic technologies. The results indicate that the high work function of the capping contact metal electrode has a negative influence on MgF x /Mg as the electron‐selective contact. Although the exact mechanism is still unclear, low‐work function metals appear to perform better. The contact stacks devised with these novel insights (1.5 nm MgF x /20 nm Mg/100 nm Al) and MoO x are applied as well to dopant‐free multilayer back‐contact (MLBC) solar cells to achieve an efficiency of 22.1% with an aperture area of 4.5 cm 2 by directional evaporation for patterning.