Co‐Assembled Layers for High Performance Wide Bandgap Inverted Perovskite Solar Cells

Why It Matters

The breakthrough lifts efficiency and durability limits of wide‑bandgap perovskite top cells, a critical step toward commercially viable tandem solar modules.

Key Takeaways

• AH‑SAM reduces halide vacancy defects.
• Open‑circuit voltage reaches 1.27 V.
• Efficiency peaks at 22.97% for wide‑bandgap cells.
• Stability retains 96% after 1,000 h operation.
• UV resistance of HTL significantly improved.

Pulse Analysis

Wide‑bandgap perovskite solar cells are the preferred top‑cell architecture for tandem photovoltaics because they can harvest high‑energy photons while allowing a low‑bandgap bottom cell to capture the remainder of the solar spectrum. However, their performance has been hampered by interfacial voltage losses and rapid light‑induced degradation, especially under UV exposure. Traditional hole‑transport layers such as Me‑4PACz, though widely adopted, suffer from aggregation and insufficient defect passivation, limiting open‑circuit voltage and long‑term stability.

The new co‑assembled layer, AH‑SAM, integrates aminoguanidine dihydrochloride into the Me‑4PACz matrix, creating cation‑π interactions with the carbazole core and electrostatic bonding to the phosphate group. This dual chemistry simultaneously passivates halide vacancies and suppresses the self‑aggregation of Me‑4PACz, resulting in a smoother, more intimate interface. The lowered HOMO level of the HTL improves energy‑level alignment, enabling an unprecedented 1.27 V open‑circuit voltage and a 22.97% power conversion efficiency—among the highest reported for 1.67 eV bandgap devices. Moreover, the AH‑SAM coating enhances UV resistance, a key factor for operational durability.

The implications extend beyond a single device record. By delivering both high efficiency and robust stability, AH‑SAM paves the way for scalable tandem modules that can meet or exceed the 30% efficiency threshold required for utility‑scale deployment. The approach is compatible with existing solution‑processing techniques, suggesting a low‑cost pathway for manufacturers. Future research will likely explore the adaptability of this co‑assembly strategy to other transport layers and perovskite compositions, potentially unlocking further performance gains across the broader perovskite solar market.