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

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.