Perylenocarbazole-Based Polycyclic Aromatic Self-Assembled Monolayers with Tailored Electrostatic Potentials for...

The development of universal hole-transporting layers for organic and perovskite solar cells (OSCs/PSCs) remains challenging due to the lack of molecular strategies that precisely control interfacial energetics, molecular packing, and active layer morphology. Here, we report an electrostatic potential (ESP)-guided approach to construct nitrogen-containing polycyclic aromatic self-assembled monolayers (SAMs) that address this challenge. By integrating a rigid, planar perylenocarbazole (PCz) core with extended π-conjugation, alkyl chain optimization, and bromination, we designed two novel SAMs, 4PCzBr and 6PCzBr, with precisely tailored ESP distributions. Compared to conventional carbazole-based SAMs, these designs substantially elevate the average ESP, strengthen intermolecular π-π interactions, and promote dense, ordered monolayer formation on ITO, thereby enhancing work function alignment and hole extraction. Interestingly, the elevated ESP of 6PCzBr strengthens electrostatic interactions with the donor PM6, driving preferential donor crystallization at the buried interface and establishing an ideal vertical phase separation for efficient charge transport. Leveraging this synergy, 6PCzBr-based OSCs deliver an outstanding efficiency of 20.16%, while inverted PSCs achieve a remarkable efficiency of 26.20% with decent operation stability. This work establishes ESP-engineered polycyclic aromatic SAMs as a versatile interfacial platform bridging organic and perovskite photovoltaics, offering a broadly applicable molecular design paradigm for high-efficiency and stable solar cells.