Advancing 1.84 eV Wide‐Bandgap Perovskite Photovoltaics Beyond 20% via Single‐Facet‐Oriented Self‐Assembled Molecules

Abstract

ABSTRACT Uncontrolled crystal growth and structural heterogeneity in solution‐processed self‐assembled molecules (SAMs) remain major limitations for efficient interfacial charge transport. Herein, we report a dipole‐engineered molecular strategy to regulate SAMs crystallization through the rational design of fluorinated benzimidazole‐carboxylic acid (BzIm‐COOH) derivatives (1F‐COOH, 2F‐COOH, and 3F‐COOH). Co‐assembly of these molecules with the parent SAMs induces strong electrostatic and dipole‐dipole interactions that direct crystal growth along the (100) facet, converting the SAMs layer from a polyfaceted, disordered morphology into a highly oriented architecture. Among them, 3F‐COOH, possessing the largest molecular dipole moment, exhibits the most pronounced facet‐directing capability. In addition to structural regulation, the BzIm‐COOH molecules optimize the interfacial energetics at the hole‐transport‐layer/perovskite junction, enabling more efficient hole extraction. Meanwhile, strong chemical interactions between 3F‐COOH and the perovskite precursor regulate crystallization kinetics and passivate interfacial defects. Consequently, wide‐bandgap (1.84 eV) PSCs incorporating 3F‐COOH deliver a champion efficiency of 20.16% (certified 19.25%) with markedly improved operational stability (90.38% after 600 h). The strategy further enables 26.75% perovskite/organic tandem devices and extends to 1.67 eV perovskite devices (23.56%) and perovskite/silicon tandems (32.34%, certified 31.54%). This work establishes dipole‐engineered molecular engineering as a powerful approach for directing SAMs crystallography and optimizing charge‐selective interfaces.