Tripodal Carboxylate Bridge Enables Buried Interface Passivation Toward High‐Performance and Durable Perovskite Solar Cells

Why It Matters

Dual‑sided interfacial passivation lifts both efficiency and operational stability, narrowing the gap between laboratory performance and commercial deployment of perovskite photovoltaics.

Key Takeaways

• NTANa passivates both Sn4+ and Pb2+ defects at SnO2/perovskite interface.
• Tripodal geometry enables dual-sided coordination, unlike linear carboxylates.
• Modified cells achieve 25.32% efficiency with 0.84 fill factor.
• Operational stability reaches T90 of 836 hours under continuous illumination.
• Enhanced electronic coupling improves electron transport and reduces ion migration.

Pulse Analysis

Perovskite solar cells have surged in research labs due to their high theoretical efficiencies, yet trap states at buried interfaces—particularly between the electron‑transport layer (SnO₂) and the perovskite absorber—remain a persistent loss mechanism. Conventional passivation molecules, such as monodentate sodium acetate or bidentate sodium oxalate, can bind to undercoordinated metal ions but their linear structures limit interaction to a single side of the interface, leaving complementary defect sites exposed. This asymmetry hampers charge extraction and accelerates ion migration, curbing both power conversion efficiency and long‑term stability.

The study leverages nitrilotriacetic acid trisodium (NTANa), a tridentate, three‑dimensional carboxylate that acts as a bifacial bridge. Its three carboxylate “teeth” reach out in a spatially distributed fashion, anchoring simultaneously to Sn⁴⁺ on the transport‑layer side and Pb²⁺ on the perovskite side. This dual coordination not only neutralizes deep‑level traps but also tightens the electronic coupling across the interface, lowering the energetic barrier for electron transfer and aligning the conduction bands more favorably. The result is a smoother charge‑carrier pathway that mitigates recombination and suppresses ion drift under bias.

Performance metrics validate the molecular design: NTANa‑treated devices deliver a certified 25.32 % power conversion efficiency, surpassing the 24 % benchmark that has defined recent commercial interest. Moreover, the unencapsulated cells retain 90 % of their initial output after 836 hours of continuous one‑sun operation, a stability figure that rivals early‑stage silicon modules. By demonstrating that multidentate passivation can simultaneously boost efficiency and durability, the work paves a practical route toward scalable, high‑performance perovskite photovoltaics, encouraging further exploration of three‑dimensional ligand architectures for next‑generation solar technologies.