Step-by-Step Fabrication of an Array of Graphene Solar Cells on 100 mm Silicon Wafer.

Graphene-based solar cells have emerged as promising candidates due to graphene's unique properties, such as high electrical conductivity, optical transparency, and mechanical flexibility.

In this talk, we present step-by-step details on how to make graphene solar cells. We produce 96 solar cells from one commercially available 100 mm diameter silicon wafer coated with a high-quality thick wet thermal oxide layer. The wafer is first split into four quadrants, and each quadrant is further divided into six chips, resulting in 24 nearly similar chips from one wafer. Each chip, measuring 16.7 mm per side, contains four solar cells processed in parallel. The fabrication process involves removing the oxide layer over a large select region, depositing metal contact pads both on the remaining oxide region and on the bare silicon, and transferring commercially available large-area graphene to the exposed silicon to create the photovoltaic interface. For the graphene contact pad, we use a special shape consisting of a square bonding pad and a rectangular stem. The purpose of the stem is to contact the graphene without the graphene touching the bonding pad. The graphene is positioned atop the large silicon region but also touches the rectangular stem. This procedure leaves the square bonding pad free of graphene to aid the wire bonding process during packaging.