The purpose of development of Laser doping via boron paste as well as related doping process is applied to the LBSF in p-PERL cells or the SE structure in N-TOPCon cells.

1. By laser doping, surface boron concentration could be over 1E20cm^-3 and better electrode contact could be formed.

2. The depth of LBSF could be adjusted by doping process, and adapted simultaneously   to Aluminum slurry and its sintering process, obtaining a stable LBSF.

3. Improving cell’s Voc and efficiency.