Novel plating processes for silicon heterojunction solar cell metallization using a structured seed layer

We present metallization approaches for silicon heterojunction solar cells by plating onto a structured seed layer. Our approaches do not require expensive processing steps or consumables. The process starts with a full area deposition of a dielectric or alternatively a blanket metal layer such as Al onto indium tin oxide (ITO). Next, the grid-shaped seed layer is applied via printing or laser-transfer. An efficiency of 22.2% was obtained using a dielectric layer and laser-transfer, outperforming screen-printing by 0.4%. Applying Al instead of a dielectric has the advantage that the plating current spreads more homogeneously on the solar cell surface, which is of particular importance for plating on bifacial solar cells. For using an Al blanket layer on top of ITO and a grid-shaped seed layer, we developed a plating process that selectively plates on the seed layer and not on the Al layer.