Universal Sacrificial Coordination Strategy for ALD-Resilient SAMs Achieving High-Performance Perovskite/Organic Tandem Solar Cells.

Abstract

Perovskite/organic tandem solar cells (TSCs) offer a compelling route to surpass the Shockley-Queisser limit. In these TSCs, the self-assembled monolayer (SAM), functioning as the hole extraction layer, critically governs the interfacial properties and device performance. Atomic layer deposition (ALD) is a promising technique to grow dense, pinhole-free oxides on SAMs for improved wettability and leakage blocking. However, the detrimental reaction between the ALD precursor and SAM anchoring groups, which causes SAM desorption and severe current leakage, is a widespread and unresolved issue. To address this fundamental challenge, we developed a universal sacrificial coordination (SC) strategy by introducing a multifunctional 6‑hydroxy‑4‑(trifluoromethyl)nicotinic acid (HTFNA) into SAM precursors. HTFNA can suppress SAM molecular aggregation through hydrogen bonding, preferentially react with the ALD precursor to shield the anchored SAM, and increase the work function for favorable interfacial energy level alignment. This strategy demonstrates broad applicability across various SAM-based devices. The champion perovskite/organic TSCs deliver a remarkable efficiency of 27.03% (certified of 26.56%; 0.062 cm²). Moreover, the reinforced SAM/perovskite heterointerface exhibits substantially enhanced adhesion according to the ASTMD3359 standard, leading to superior operational stability (T₉₀ of 1265 h) and ambient storage performance (T₉₀ of 2037 h; ISOS-D-1 protocol).