Schottky-type edge passivation of silicon solar cells

- Full wafer Si solar cells were tested for Schottky-type edge passivation.
- The cell edges surrounding wafer were coated by an Ag nanoink and processed.
- The regions of laser edge-cut and edge pn junction were covered by the annealed Ag metal.
- The short circuit current was a little reduced but the fill factor was enhanced by the Schottky-type edge passivation.
- The conversion efficiency is found to increase compared to reference cells.

We investigated Schottky-type edge passivation of Si solar cells using Ag nanodots and the enhancement of cell conversion efficiency by improving the fill factor. The threshold voltage for the termination of photocurrent is increased by about 0.13 V compared to the reference sample without edge passivation. The cross-section of the pn junction depletion region forms an Ag/Si Schottky contact in the depletion layer of the space and the image charges with a width of about 28 nm. However, the p- and n-electrodes form Ohmic contacts with a contact depletion width of less than 5 nm for the carrier tunneling process. The edge Schottky contact reduces the carrier recombination and saturation current at the surrounding edge region and enhances the fill factor and the pn junction property with increased shunt resistance, indicating that metallic edge passivation is an important process for large-scale Si solar cell fabrication.