Dual‐Function Interface Engineering of SnO2 Electron Transport Layers: Wettability Enhancement and Work Function Tuning for Efficient and Stable Perovskite Solar Cells and Minimodules

Why It Matters

The breakthrough offers a scalable, solution‑processable route to combine high efficiency with long‑term stability, addressing two major barriers to commercializing perovskite photovoltaics.

Key Takeaways

• PEI improves SnO2 wettability and work function
• Modified ETL yields 24.49% PCE in lab cells
• 24.8 cm² minimodules reach 22.56% efficiency
• Modules retain 94% performance after 500 h
• Dual-function engineering suppresses oxygen vacancies

Pulse Analysis

Perovskite solar cells have surged ahead of traditional silicon technologies thanks to their high absorption coefficients and low‑temperature processing, yet their commercial rollout stalls on two fronts: interface losses and long‑term degradation. Electron transport layers (ETLs) such as SnO2 are pivotal for extracting electrons, but intrinsic oxygen vacancies create trap states that sap efficiency. By embedding polyethyleneimine (PEI) into the SnO2 matrix, researchers introduce amine groups that both increase surface energy—improving perovskite wetting—and generate a dipole that lowers the SnO2 work function. This dual-action passivates defects and aligns energy levels, fostering uniform crystal growth and faster carrier extraction.

The performance gains are striking. Laboratory‑scale PSCs equipped with PEI‑SnO2 ETLs reached a power conversion efficiency (PCE) of 24.49 %, rivaling the best reported perovskite cells. More importantly, the technique translated to 24.8 cm² minimodules that delivered 22.56 % PCE, a rare demonstration of high efficiency at a near‑module scale. Stability tests showed the modules retained 94 % of their initial output after 500 hours of continuous illumination, indicating that the interfacial engineering also mitigates degradation pathways that typically plague perovskite devices.

From a market perspective, the solution‑processable, ambient‑compatible PEI treatment aligns with roll‑to‑roll manufacturing, reducing the need for costly vacuum deposition steps. This lowers capital expenditure and accelerates the path to gigawatt‑scale production. As investors and utilities seek renewable options with higher energy density and lower balance‑of‑system costs, such scalable interface engineering could be the catalyst that pushes perovskite photovoltaics from pilot lines into mainstream deployment. Future research will likely explore synergistic additives and encapsulation strategies to push both efficiency and operational lifetimes beyond current benchmarks.