(a–c) Schematic drawing of the structure of a POLO²-IBC solar cell with (a) a thermally grown SiO₂ layer, (b) Al₂O₃/SiN_y/SiO_z or (c) PECVD-SiO_z/SiN_y stack as the rear side dielectric layer. (d–f) Spatially resolved carrier lifetime of the cell structures shown in (a–c) at ∼0.25 suns measured by the ILM method. The active cell areas of the seven solar cells are marked with squares a–g.