A Low-Cost Solar-Cell Front Contact Using Trapped Silver Mesh and Electrostatic Bonding

One of the major costs of modern solar-cell manufacture is that of applying a metallized contact grid to the cell front surface. If solar energy is to become a viable source of !ow-cost electricity, this expense must be reduced significantly. To keep efficiency high, a metallization grid must provide narrow closely spaced high conductivity lines. A new system to provide this contact with a silver mesh trapped between the cell and an encapsulating glass cover has been demonstrated. Borosilicate glass is permanently joined to the cell by electrostatic bonding, an adhesive-free field-assisted glass-metal sealing technique. During this process the glass is deformed around the silver mesh to form a permanent optically coupled integral bond to the cell. This hermetic seal prevents the silver from oxidizing and destroying the electrical contact formed during the bonding process. Cells produced this way have been demonstrated with curve fill factors of 0.69. A thin titanium layer evaporated on the mesh seems to improve the results. Specific contact resistance measured for this system is on the order of 20-30 m -cm2.