A Ni/Ag Plated TOPCon Solar Cell with a Laser-Doped Selective Emitter via Different Boron-Based Coatings

Laser-doped selective emitter diffusion has become a mainstream technique in solar cell manufacturing because of its superiority over conventional high-temperature annealing. In this work, a boron-doped selective emitter is prepared with the assistance of picosecond laser ablation, followed by a Ni-Ag electrodeposited metallization process. The introduction of boron dopant is accomplished in an efficient and simple way—preparing different boron-doped coatings (dimethylaminoborane and boron powder coatings) followed by laser ablation. Of the two coatings, boron powder provides a selective emitter with a higher carrier concentration of N_p = 8.08 × 10²¹ cm⁻³, leading to an increase of 0.046 V in the built-in potential of the PN junction and a decrease in the contact resistance. As a result, the maximum open-circuit voltage reaches 0.630 V, which is 30 mV higher than that of ordinary laser-ablated solar cells. Moreover, the average adhesion of the electrodes to the substrate reaches as high as 5.45 N mm⁻¹. This provides an alternative for the subsequent potential industrial applications using laser doping of selective emitters.