The investigation of implanted boron emitter for n-type bifacial silicon solar cells

Abstract

N-type silicon wafers have been more promising for developing high efficiency solar cells, and the novel technique of ion implantation has been applied for the formation of excellent quality emitters. The n-type bifacial cells have demonstrated the advantages of not only transparent sides to enhance the illuminated area for modules but also less metal paste usage for the feasibility of thin wafer applications. In this study, we achieve the fabrication of the certificated 19.45% efficiency screen-printed n-type bifacial solar cells using boron and phosphorus ion-implantation on 239 cm ² pseudosquare Cz wafers. By using appropriate implanted doses and modified post-treatment for emitter formation, a comparably low emitter saturation current density (J _oe ) of 60 fA/cm ² was achieved. Detailed emitter and base saturation current (J _ob ) along with internal quantum efficiency (IQE) analysis by PC1D simulation explain the V _oc reduction by non-optimized metallization on boron emitter side and major efficiency limitation due to J _ob .