The precise regulation of self-assembled monolayer (SAM) distribution and interfacial modification is pivotal for advancing the performance of p-i-n inverted perovskite solar cells (PSCs). Here, a new co-assembly material, 4-(aminomethyl)-N,N-diphenylaniline iodide (TPAI), is developed to make SAM orderly assembled. Density functional theory (DFT) calculation and sum frequency generation (SFG) spectroscopy reveal that TPAI binds with SAM via π-π interactions, effectively suppressing SAM aggregation and enhancing the orderliness of self-assembly. Further characterization by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrates that ─NH