IIT Bombay holds a large perovskite cell at 18.88% with a mixed monolayer

Victoria Shinder08 October 2026, 07:161 min read

Researchers at the Indian Institute of Technology Bombay have shown that a mixed self-assembled monolayer (SAM) can keep much of a perovskite cell's efficiency as it grows from laboratory size to a larger area, pv magazine reported on 6 October. The work is published in ACS Applied Materials & Interfaces.

The problem. SAMs serve as ultrathin hole-selective contacts in inverted (p-i-n) perovskite cells and have enabled efficiencies approaching 27% in small devices. But scaling from about 0.1 cm² to larger areas — especially with wide-bandgap absorbers — usually costs a lot of efficiency.

The fix. The team mixed two carbazole-based molecules: Me-4PACz, which brings good energy-level alignment and hole extraction, and 4PADCB, which improves wetting and film formation.

The numbers.

• At 1.2 cm²: 20.30% efficiency and 81.23% fill factor, against 18.17% and 19.30% for the two molecules used alone.
• At 5.2 cm²: a best efficiency of 18.88%, against 17.20% and 17.96%; the average was 17.81% versus 18.96% for smaller cells — a relative loss of about 7%.
• Stability: under damp heat at 85 °C and 65% relative humidity, the cells took more than 680 hours to fall to 75% of their initial efficiency.

The authors trace most of the scaling loss to series resistance in other interfaces and in the transparent conductive electrode, not to the absorber itself — which points the next round of work at the electrode rather than the perovskite. They also note the mixture is solution-processable and should be compatible with blade, slot-die and spray coating.