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 Seff to Seff<20 cm s−1. Due to the optimized back side layer sequence, the open circuit voltage VOC rises by ΔVOC=15 mV up to VOC=622 mV and the short circuit current increases by ΔJSC=0.8 mA cm−2.