| Summary: | Reducing the interfacial defects between the perovskite/electron transport layer (ETL) is the key point to improving the efficient and stable performance of perovskite solar cells (PSCs). In this study, two self-assembled molecules ((aminomethyl)phosphonic acid and glycine) with different functional groups (phosphonic acid (-H<sub>2</sub>PO<sub>3</sub>) and carboxylic acid (-COOH)) were mixed to form the buried bottom interface of PSCs. The synergistic effect of -H<sub>2</sub>PO<sub>3</sub> with its higher anchoring ability and -COOH with its fast carrier transport improved the performance of PSCs. Additionally, the SnO<sub>2</sub> modified by mixed self-assembly molecules (M-SAM) showed a more appropriate energy level alignment, favoring charge transport and minimizing energy loss. In addition, the amine group (-NH<sub>2</sub>) on the two small molecules effectively interacted with uncoordinated Pb<sup>2+</sup> in perovskite and improved the quality of the perovskite films. Consequently, the (FAPbI<sub>3</sub>)<sub>0.992</sub>(MAPbBr<sub>3</sub>)<sub>0.008</sub> PSCs with M-SAM reached a PCE of 24.69% (0.08 cm<sup>2</sup>) and the perovskite modules achieved a champion efficiency of 18.57% (12.25 cm<sup>2</sup> aperture area). Meanwhile, it still maintained more than 91% of its initial PCE after being placed in nitrogen atmosphere at 25 °C for 1500 h, which is better than that of the single-SAM and control devices. Further reference is provided for the future commercialization of perovskite with efficient and stable characteristics.
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