Investigation of high-efficiency screen-printed textured Si solar cells with high sheet-resistance emitters

In this study it is found that the efficiency enhancement (Δη) resulting from the use of a 100 Ω/sq emitter instead of a conventional 45 Ω/sq emitter is substantially enhanced further by surface texturing. This enhancement is greater for textured cells by at least ∼0.4% absolute over the enhancement for planar cells, and is mainly due to the greater difference in the front-surface recombination velocity (FSRV) between the high-and low-sheet-resistance emitter textured cells. A FSRV of 60,000 cm/s resulted in a reasonably good V_oc of ∼642 mV for the 100 Ω/sq emitter textured cell. Our investigation of the Ag-Si contact interface shows a more regular distribution of Ag crystallite precipitation for the textured emitter (mainly at the peaks of the texture pyramids). The high contact-quality resulted in a series resistance of 0.79 Ω-cm, a junction leakage current of 18.5 nA/cm² yielding a FF of 0.784. This resulted in a record high-efficiency 4 cm² screen-printed cell of 18.8% (confirmed by NREL) on textured 0.6 Ω-cm FZ, with single-layer antireflection coating.