Method for producing a via in a III-V multijunction solar cell

A method for producing a via in a III-V multijunction solar cell, which has an upper side and an underside, the via being designed to pass through from the upper side to the underside, the III-V multijunction solar cell comprising a substrate arranged on the underside, the substrate having an upper side and an epitaxial layer system with multiple III-V layers formed on the upper side, the epitaxial layer system comprises at least one first III-V solar cell, an organic layer being arranged on the upper side of the first III-V solar cell, the method comprising:

• forming an opening having a width X and a having a first base surface in the epitaxial layer system, the opening being formed via a laser;
• forming an opening having a width Y and a second base surface in the substrate, the opening being formed via the laser, the width Y being smaller than the width X;
• and
• forming an opening having a width Z with the laser to form a continuous via, the opening not having a base surface, and width Z being smaller than width Y.