Quinoxaline derivatives modification of nickel oxide interfaces for scalable perovskite solar cells

Interfacial recombination at the NiO x /perovskite interface remains a key limitation to the efficiency and scalability of perovskite solar cells (PSCs), especially under ambient-air fabrication conditions. In this study, we introduce quinoxaline-based bifunctional organic molecules containing a dicarboxylic acid functional group (Qu-COOH) or a dicyano functional group (Qu-CN) as an interfacial modifier to passivate surface defects and tune the energy alignment between NiO x and perovskite. Compared to Qu-CN, Qu-COOH-modified NiO x exhibited improved Ni 3+ /Ni 2+ ratios and deeper work function, which established a favorable interfacial dipole to facilitate hole extraction and reducing interfacial recombination. Spectroscopic and electrical analyses, reveal that the Qu-COOH layer effectively passivates buried interface defects, not only accelerating charge extraction dynamics but also minimizing trap-assisted and non-radiative recombination. As a result, devices based on Qu-COOH-modified NiO x achieved a power conversion efficiency (PCE) of 18.22 %, significantly higher than the 13.44 % of unmodified controls. The Qu-COOH modification also exhibited scalable manufacturability, which, upon incorporation into an ambient-compatible sequential slot-die coating process, yielded large-area 5 × 5 cm 2 perovskite solar modules (PSMs) with a PCE of 14.49 % and excellent spatial uniformity. In terms of device stability, unencapsulated Qu-COOH-modified devices retained over 80 % of their initial efficiency (T 80 ) after 800 h of storage in dry air, an over 400 % improvement over the control. This work highlights the dual role of Qu-COOH as both an electronic passivator and a morphological regulator, offering a viable route toward scalable, ambient-stable PSCs.