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All-perovskite tandem solar cells are a promising photovoltaic technology, but their efficiency is strongly limited by the tunnel junction. The tunnel junction enables carrier tunneling and recombination, which depend on the interfacial band alignment. Through quantitative simulations using Silvaco Technology Computer Aided Design (TCAD), we find that hole tunneling is intrinsically more difficult than electron tunneling in the tunnel junction. Efficient tunnel junctions require minimizing the barrier for holes while maintaining a moderate barrier for electrons to balance tunneling. For the SnO2/metal/PEDOT:PSS tunnel junction in all-perovskite tandem solar cells, tuning the metal work function achieves balanced electron and hole tunneling, reduces junction resistance, and directly enhances performance of tandem solar cells. This work provides quantitative design rules for tunnel junction optimization, offering a clear pathway toward high-performance all-perovskite tandem solar cells.
Yang et al. (Thu,) studied this question.