Mass production of industrial tunnel oxide passivated contacts (i‐TOPCon) silicon solar cells with average efficiency over 23% and modules over 345 W

Abstract We present an industrial tunnel oxide passivated contacts (i‐TOPCon) bifacial crystalline silicon (c‐Si) solar cell based on large‐area n ‐type substrate. The interfacial thin SiO 2 is thermally growth and in situ capped by an intrinsic poly‐Si layer deposited by low‐pressure chemical vapor deposition (LPCVD). The intrinsic poly‐Si layer is doped in an industrial POCl 3 diffusion furnace to form the n + poly‐Si at the rear, which shows an excellent surface passivation characteristics with J 0 = 2.6 fA/cm 2 when passivated by a SiN x :H layer deposited by plasma‐enhanced chemical vapor deposition (PECVD). With an industrial fabrication process, the cells are manufactured with screen‐printed front and rear metallization, using large‐area 6‐in. n ‐type Czochralski (Cz) Si wafers. We demonstrate an average front‐side efficiency greater than 23% and an open‐circuit voltage V oc greater than 700 mV. These results are based on more than 20 000 pieces of cells from mass production on a single day, in an old conventional multicrystalline silicon (mc‐Si) Al‐back surface field (BSF) cell workshop, which has been upgraded to i‐TOPCon process. The best cell efficiency reaches 23.57%, as independently confirmed by Fraunhofer CalLab. A median module power greater than 345 W and a best module power greater than 355 W are demonstrated with double‐glass bifacial i‐TOPCon modules consisting of 120 pieces of half‐cut 161.7 mm pseudosquare i‐TOPCon cells with nine busbars.