Crosslinked Conjugated Interlayer Network for Efficient and Stable Wide-Bandgap Perovskite and All-Perovskite Tandem Solar Cells

Compared to single-junction perovskite solar cells (PSCs), all-perovskite tandem solar cells (PTSCs) offer higher power conversion efficiencies (PCEs). However, the substantial open-circuit voltage (V_OC) loss of wide-bandgap (WBG) perovskite sub-cells limits the efficiency due to the interface defect and halide segregation. In this study, 6-hydroxy-2-naphthalenecarboxylic acid (HNA) is employed to construct cross-linked network by the H-bond and conjugated interaction to engineer the interface and suppress halide segregation. Enhanced Photoluminescence (PL) intensity and reduced quai-Fermi level splitting (QFLS) loss indicate that the unique molecular conformation of HNA facilitates the process of the dense crosslinked film, which greatly enhances the passivation effect. Meanwhile, the strong π-π interactions accelerate the charge transport at the WBG perovskite/C₆₀ interface, effectively suppressing the non-radiative recombination. The 1.78 eV WBG PSCs achieve a V_OC of 1.35 V and a PCE of 19.92% and deliver T₈₀ = 1100 h by maximum power point track (MPPT). In combination with narrow-bandgap (NBG) sub-cells, PTSCs exhibit a V_OC of 2.13 V, a PCE of 28.25%, and T₈₀ of 500 h. This work provides a self-assembled interlayer strategy to develop highly efficient and stable WBG sub-cells for PTSCs.