Improved silver paste allows 19%-efficient c-Si solar cell with homogeneous high-sheet-resistance POCl3 emitter

The emitter saturation current density (J_0e) of the industrial p-type c-Si solar cell can be reduced by thinning the n⁺⁺ top layer of the phosphorus emitter. A simple approach to the shallower emitter is to aim for a higher sheet resistance with the POCl₃ diffusion process. We have fabricated high-efficiency solar cells with a homogeneous emitter of 80 Ω/sq sheet resistance, by employing a commercial Ag paste designed for an improved electrical contact to the high-resistance emitter. The average efficiency improves by 0.4%_abs, with the champion cell showing 19.0% efficiency. Industrial 156 mm p-type Cz sc-Si wafers were used.