Sputtered nickel oxide (NiOx) is an attractive hole-transport layer for efficient, stable, and large-area p-i-n metal-halide perovskite solar cells (PSCs). However, surface traps and undesirable chemical reactions at the NiOx/perovskite interface are limiting the performance of NiOx-based PSCs. To address these issues simultaneously, an efficient NiOx/perovskite interface passivation strategy by using an organometallic dye molecule (N719) is reported. This molecule concurrently passivates NiOx and perovskite surface traps, and facilitates charge transport. Consequently, the power conversion efficiency (PCE) of single-junction p-i-n PSCs increases from 17.3% to 20.4% (the highest reported value for sputtered-NiOx based PSCs). Notably, the N719 molecule self-anchors and conformally covers NiOx films deposited on complex surfaces. This enables highly efficient textured monolithic p-i-n perovskite/silicon tandem solar cells, reaching PCEs up to 26.2% (23.5% without dye passivation) with a high processing yield. The N719 layer also forms a barrier that prevents undesirable chemical reactions at the NiOx/perovskite interface, significantly improving device stability. These findings provide critical insights for improved passivation of the NiOx/perovskite interface, and the fabrication of highly efficient, robust, and large-area perovskite-based optoelectronic devices.