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

Abstract

AbstractWe 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 SiO2 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 POCl3 diffusion furnace to form the n+ poly‐Si at the rear, which shows an excellent surface passivation characteristics with J0 = 2.6 fA/cm2 when passivated by a SiNx: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 Voc 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.