19.7% Efficient All-Screen-Printed Back-Contact Back-Junction Silicon Solar Cell With Aluminum-Alloyed Emitter

A back-contact back-junction solar cell on n-type silicon with an aluminum-alloyed emitter is introduced, where both structuring and metallization are realized by screen-printing. The process sequence for realizing the cell with a pitch of 2 mm is displayed and described. The cell parameters are shown for three different emitter coverages on the rear side (45%, 58%, and 72%). An analysis of the saturation current density J_ο of the different areas was carried out on lifetime samples, and the calculated V_oc is compared to the measured one. The potentially critical edge of the Al finger is analyzed in a scanning electron microscopy cross section. No damaging of the aluminum paste to the passivation layer and a homogenous p+-layer over the whole finger width is observed. A conversion efficiency of 19.7% is presented for a cell with an aperture area of 16.65 cm² that was exclusively processed in Fraunhofer ISE PV-TEC, which is an industrial-like fabrication environment.