Self‐powered light‐induced plating for III‐V/Ge triple‐junction solar cell metallization

We present a new process to deposit thick front emitter contact on multijunction solar cells using a self‐powered light‐induced plating (SP‐LIP). This electrochemical deposition method is based on the use of the light‐induced polarization of the cell to drive the plating current instead of the use of an external power supply as for standard electroplating. The electrical characterization of the process is performed by current and potential measurements at various light intensities and enables the deposition of thick layers of various metals (Ag, Ni, and Au) on triple‐junction solar cells with a precise control of the metal thickness. The potential of SP‐LIP for the deposition of an ohmic contact layer directly on the solar cell front side without any seed layer is also demonstrated. A triple‐junction solar cell fabricated with both ohmic and thick metal front contact deposited only by an electrochemical method is reported. We present a self‐powered light‐induced plating (SP‐LIP) technique for the deposition of thick emitter contact of III‐V/Ge triple‐junction solar cell. Contrary to standard electroplating and light‐induced plating processes, the solar cell is the only source of current and polarization and there is no need for an external power supply. This approach leads to a simplified, rapid, and low‐cost process for solar cell fabrication since the front side could be completed using a single photolithography step followed by immersion in electroplating solution and exposition to a controlled light beam. We demonstrate the potential of this technique both for deposition of the ohmic contact and for thick contact in a seedless process scheme.