Multifunctional Conjugated Ligands Synergistically Optimize the Interface and Regulate Crystallization for High‐Performance 2D/3D Perovskite Solar Cells

ABSTRACT The interfacial optimization of self‐assembled monolayers (SAMs) and precise regulation of perovskite crystallization process are crucial for improving the performance and stability of inverted perovskite solar cells (PSCs). Herein, we designed two multifunctional conjugated cationic ligands (TDZI and TzTzI) to modify the SAMs/perovskite interface. This study reveals that the conjugated ligands form tighter and ordered π–π stacking with [4‐[(3,6‐dimethyl‐9H‐carbazol‐9‐yl) butyl] phosphonic acid (Me‐4PACz), efficiently suppressing Me‐4PACz aggregation. Meanwhile, ligands dissolved in the perovskite precursor induce the bottom‐up growth of 2D/3D heterojunction, which effectively regulates perovskite crystallization process and suppresses defect formation, thereby yielding high‐quality and uniform perovskite films. These synergistic effects enhance the adhesion of SAM/perovskite interface, reduce interfacial non‐radiative recombination loss, and accelerate the extraction and transport of carriers. Finally, the inverted PSCs modified with TzTzI achieved an exceptional power conversion efficiency (PCE) of 26.61% with a high open‐circuit voltage ( V oc ) of 1.204 V, which is among the highest efficiencies reported to date for 2D/3D heterojunction PSCs. Moreover, the unencapsulated devices exhibit excellent humidity, thermal and operational stability under the ISOS protocols. Excitingly, the TzTzI‐based PSCs delivered outstanding PCEs of 24.5% for 1 cm 2 devices, 20.61% for devices with 1.72 eV bandgap, and 22.14% for mini‐modules.