Balancing carrier transport in interconnection layer for efficient perovskite/organic tandem solar cells

While individual perovskite and organic solar cells have demonstrated remarkable performance, achieving similar success in high-efficiency perovskite/organic tandem solar cells (TSCs) has been challenging, primarily due to large voltage deficits and severe non-radiative recombination. By exploring the fundamental mechanisms of carrier losses, we identify that imbalanced carrier transport, particularly inadequate hole transport in the organic subcell significantly limits the overall performance of perovskite/organic TSCs. Herein, we implement a hole transport self-assembled monolayer (SAM) anchored to MoO₃, which converts the inherently n-type MoO₃ to a p-type surface. Further, a SAM/MoO₃/SAM sandwich hole transport configuration is introduced, which significantly enhances hole extraction, facilitating a more balanced carrier transport, and markedly suppressing non-radiative recombination at the interconnection layer (ICL). The resulting perovskite/organic TSCs achieve a power conversion efficiency (PCE) of 26.05%, with an open-circuit voltage of 2.21 V (certified at 2.216 V) and enhanced operation stability.