Self-Assembling Material Extends Life, Raises Output of Tandem Perovskite Cells

• South Korean scientists create a self-assembling interlayer that pushes perovskite/organic tandem solar cells to 24.7 % efficiency while surviving high-heat stress, edging flexible photovoltaics toward market readiness.

A South Korean research team has unveiled a wafer-thin coating that could push next-generation solar panels closer to commercial reality by lifting both efficiency and durability in one stroke. Working across Ulsan National Institute of Science and Technology (UNIST), the University of Ulsan and Kunsan National University, the scientists engineered a “multi-functional hole-selective layer” (mHSL) that slips between the light-harvesting perovskite film and the front electrode of a tandem solar cell.

Perovskite/organic tandems already stack two distinct absorbers to capture a wider slice of the solar spectrum, yet losses at the interface between layers have capped their potential. The new mHSL—formed from two self-assembling molecules dubbed 36ICzC4PA and 36MeOCzC4PA—realigns those interfaces at the molecular level. By matching energy levels with uncanny precision, the coating pulls positive charges (holes) toward the electrode while repelling electrons, slashing the recombination that usually saps voltage.

In lab tests the prototype cell recorded an open-circuit voltage of 2.216 volts and a power-conversion efficiency of 24.73 percent, placing it among the global elite for perovskite-organic tandems. Just as striking, the device clung to more than 80 percent of its initial output after continuous light bombardment at 65 °C, conditions that normally shred delicate perovskite films within days.

That staying power stems from chemistry as much as physics. Side chains on the self-assembled molecules bond tightly to lead and other metal ions inside the perovskite, locking the crystal lattice in place and sealing off defect sites. The result is a uniform, nanometre-scale film that deposits in a single step—no high-vacuum equipment required. The simplicity hints at roll-to-roll production for flexible modules on rooftops, car exteriors or even backpack fabrics.

Professor Jang-Hyuk Kim, who led the study published in Advanced Energy Materials, called the work “a significant leap toward thin, lightweight solar panels that can power real-world devices.” The team is now collaborating with industrial partners to scale the process and test larger-area cells under outdoor conditions.

With silicon photovoltaics already squeezing costs to record lows, tandem technologies must prove they can out-perform without sacrificing longevity. This self-assembling interlayer shows one pathway—chemistry designed to work for, rather than against, the fragile marvel that is perovskite.