24.58% total area efficiency of screen-printed, large area industrial silicon solar cells with the tunnel oxide passivated contacts (i-TOPCon) design

Abstract

We demonstrate an “industrial tunnel oxide passivated contacts” (i-TOPCon) silicon solar cell on large area n-type silicon wafers (156.75 mm × 156.75 mm). This cell has a boron diffused front emitter, a tunnel-SiOx/n+-poly-Si/SiNx:H structure at the rear side, and screen-printed electrodes on both sides. The passivation of the tunnel-SiOx/n+-poly-Si/SiNx:H structure on silicon wafers is investigated. The saturation currents Jo of this structure on polished and textured silicon surfaces are 1.3 and 3.7 fA/cm2, respectively. After printing the Ag contacts, the Jo of this structure increases to 50.7 fA/cm2 on textured silicon surfaces, which is still manageably low for metal contacts. This structure was applied to i-TOPCon solar cells, resulting in a median efficiency of 23.91%, measured in-house, and a champion efficiency of 24.58%, independently confirmed by the ISFH CalTeC in Germany. The champion efficiency was measured with total area illumination, including screen-printed fingers and busbars.