Defect‐Passivating and Dense Indolocarbazole‐Based Self‐Assembled Monolayers for Efficient Inverted Perovskite Solar Cells With over 26.1% Efficiency

Why It Matters

The breakthrough demonstrates that precise molecular engineering of SAMs can push perovskite efficiencies beyond 26%, narrowing the gap to commercial silicon modules and enhancing long‑term stability, a critical step toward market adoption.

Key Takeaways

• M3PAICz-1 yields 26.12% PCE in inverted PSCs.
• Meta‑position nitrogen improves wettability and film uniformity.
• Monophosphonate anchoring outperforms bis‑phosphonate for defect passivation.
• Same SAM achieves 22.19% efficiency in 1.68 eV wide‑bandgap cells.
• Enhanced stability demonstrated under ambient air exposure.

Pulse Analysis

Perovskite solar cells have surged ahead of traditional photovoltaics due to their high absorption coefficients and low‑temperature processing, yet their commercial rollout stalls on stability and reproducibility issues. Self‑assembled monolayers (SAMs) serve as ultra‑thin hole‑transport layers (HTLs) that can fine‑tune interfacial energetics, but conventional SAMs often suffer from poor wettability and incomplete surface coverage, leading to trap‑mediated recombination and degraded performance. By reconfiguring the indolocarbazole core—shifting nitrogen atoms between meta and para positions—and varying the number of phosphonate anchoring groups, the research team directly addressed these interfacial shortcomings.

The resulting M3PAICz‑1 molecule, featuring a meta‑positioned nitrogen and a single phosphonate anchor, forms a densely packed, highly wettable monolayer on NiOx substrates. This architecture aligns the highest occupied molecular orbital closely with the perovskite valence band, facilitating rapid hole extraction while simultaneously passivating surface defects. Uniform film formation reduces pinholes and suppresses non‑radiative recombination, which together translate into a certified 26.12% power conversion efficiency for a 1.55 eV bandgap device—one of the highest reported for SAM‑based inverted perovskite cells.

Beyond the headline efficiency, the study showcases the SAM’s versatility: the same molecular design boosts a 1.68 eV wide‑bandgap cell to 22.19% efficiency and maintains performance under ambient air exposure, indicating robust environmental resilience. These results suggest that strategic molecular engineering of HTLs can simultaneously tackle efficiency, stability, and scalability, accelerating the path toward commercially viable perovskite modules. Future work will likely explore further anchoring chemistries and large‑area deposition techniques to translate laboratory gains into industrial production.