ALD-Deposited Hydroxyl-Rich NiO_x to Enhance SAM Anchoring for Stable and Efficient Perovskite Solar Cells

The interface between nickel oxide (NiO_x) and self-assembled monolayers (SAMs) in perovskite solar cells (PSCs) often suffers from limited adsorption strength, poor energy-level alignment, and inadequate defect passivation, which hinder device performance and stability. To address these issues, we introduce a hybrid hole selective layer (HSL) combining atomic layer deposition (ALD)-fabricated NiO_x with full-aromatic SAM molecules, creating a highly stable and efficient interface. ALD NiO_x, enriched with hydroxyl groups, provides robust adsorption sites for the SAM molecule MeO-PhPACz, ensuring a strong, stable interaction. This hybrid HSL enhances energy-level alignment, hole selectivity, and defect passivation at the NiO_x/perovskite interface. Devices utilizing this approach demonstrate significant performance improvements, achieving a power conversion efficiency (PCE) of 21.74%, with reduced voltage losses and minimal hysteresis. Furthermore, operational stability tests reveal enhanced durability under elevated humidity and temperature conditions. These findings highlight the potential of ALD NiO_x and SAM hybrid HSL to overcome existing barriers, advancing the commercial viability of PSC technologies.