Increasing the power conversion efficiency of solar cells is not only attractive in terms of effective land use, but also a strong lever for lower levelized costs of electricity. State-of-the-art passivating and carrier-selective contacts enable the most efficient silicon solar cells. They can also be integrated in tandem solar cells, the logical successors of Si single-junction solar cells, to achieve even better power conversion. This work investigates the transport properties of silicon-based heterostructures using dedicated test structures. The transport losses of corresponding solar cells cells are significantly reduced by tailoring the interfaces in the contact stack, taking into account the trade-off between transport and passivation, leading to increased power conversion efficiency. With respect to tandem solar cells, a tunneling recombination junction is developed as sub-cell interconnection, focusing on industrial feasibility with the use of a lean process sequence and exploiting synergy effects with mainstream technology.