Development of n-type Selective Emitter Silicon Solar Cells by Laser Doping Using Boron-doped Silicon Paste

Abstract

N-type solar cells are being developed as next generation photovoltaic solar cells, and have attracted a significant amount of attention. In addition, the demand for high-efficiency silicon solar cells has increased in order to reduce production costs and save space. In this study, we demonstrate boron laser doping (LD) using a boron-doped NanoGram® Si paste in n-type passivated emitter, rear totally diffused solar cells. The sheet resistance was 54 Ω/sq at the local boron emitter after boron LD. The boron diffusion depth was ∼2.0 μm, and the boron surface concentration was 7 × 1019 atoms/cm3. The n-type solar cells were fabricated using boron LD to have front side boron selective emitters. The characteristics of the newly developed solar cells improved in comparison with those of the reference cells (i.e., those without boron selective emitters), and a maximum efficiency of 19.70% was achieved. The improved efficiency was mainly due to the increase in the short circuit current density and fill factor.