Efficiency Potential of P-Type Al₂O₃/SiNₓ Passivated PERC Solar Cells With Locally Laser-Doped Rear Contacts

Technological restrictions on the screen-printed rear-contact feature size on the order of 100 μm are among the limiting factors of the efficiency of p-type passivated emitter rear-contact (PERC) solar cells. Simultaneous contact opening and doping using localized laser processing can overcome these design limitations. We use 3-D numerical device simulations to show that an efficiency gain of 0.3%abs compared with a screen-printed baseline cell, is possible if laser-formed point contacts of 5 μm in size with a contact recombination parameter of 5000 fA·cm-2and a contact resistance of 10-4Ω·cm2are used. We experimentally demonstrate the implementation of simultaneous rear-surface contact opening and doping on large-area 156 × 156 mm2-sized PERC solar cells using ultraviolet (UV) and green laser systems. We achieve efficiencies of up to 19.9% for this process with a 10-nm atomic layer deposited Al2O3/80-nm plasma-enhanced chemical vapor deposited SiNxrear-surface dielectric stack.