0.4% absolute efficiency gain by novel back contact

Replacing the aluminum back contact of screen-printed multicrystalline silicon solar cells by a novel low-temperature layer sequence boosts the absolute power conversion efficiency η by Δη = 0.4%. The optimized hydrogenated amorphous silicon (a-Si:H)-based back side junction provides efficient back side passivation and contacting at the same time. The improved passivation quality reduces the effective surface recombination velocity S eff to S eff <20cm s -1 . Due to the optimized back side layer sequence, the open circuit voltage V oc rises by ΔV oc = 15 mV up to V oc 622 mV and the short circuit current increases by ΔJ sc = 0.8 mA cm -2 .