Large‐Area GaAs‐Based Multijunction Solar Cells by “Smart Stack” Approach Using Pd Nanoparticle Array and Silicone Adhesive

Smart stacking using Pd nanoparticle arrays is a handy technique for producing two‐terminal tandem solar cells from various photovoltaic materials. However, it is difficult to fabricate a large‐area cell because of handling ultrathin epi‐wafer. Therefore, herein, a large‐area GaAs‐based multijunction (MJ) solar cell is fabricated using a modified smart stacking method. Applying epitaxial lift‐off with a slightly adhesive sheet makes transferring an epi‐wafer of more than 2 inches possible. The fabricated InGaP/GaAs//CuIn 1− y Ga y Se 2 three‐junction solar cell of 2.6 cm × 2.6 cm square exhibits a total efficiency of 22.8%. The large‐area process demonstrates the potential of smart stack GaAs‐based MJ solar cells as next‐generation solar cells.