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

Abstract 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/C 60 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 T 80 = 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 T 80 of 500 h. This work provides a self‐assembled interlayer strategy to develop highly efficient and stable WBG sub‐cells for PTSCs.