A solar cell thinner and lighter than anything silicon can offer just hit a new world record — and it didn't come from a silicon wafer at all.

  • 26.7% certified power conversion efficiency
  • Built from a perovskite top cell stacked on a CIGS bottom cell
  • Beats the lab's own prior lightweight tandem record of 24.5%
  • Developed by the Photovoltaic Research Department at KIER

Two materials, stacked to catch more light

The record comes from the Korea Institute of Energy Research (KIER), a government-run lab that has spent years chasing tandem solar cell efficiency. A tandem cell works by layering two different light-absorbing materials — each tuned to catch a different slice of the solar spectrum — so the combined device converts more sunlight into electricity than either material could alone.

In this case, KIER's team paired a perovskite top cell with a copper indium gallium selenide (CIGS) bottom cell. Perovskite crystals are inexpensive to produce and tunable to absorb specific wavelengths, while CIGS is a well-established thin-film technology already used in commercial solar panels. Stacking the two lets the perovskite layer harvest high-energy light near the top of the spectrum while CIGS catches the lower-energy light that passes through.

Why "lightweight" is the headline, not just efficiency

Silicon solar cells still dominate the market and silicon-perovskite tandems have pushed past 34% efficiency in lab settings. So why does a 26.7% perovskite/CIGS result matter? Because unlike silicon, both perovskite and CIGS layers can be deposited as thin films on flexible, ultra-lightweight substrates — a combination silicon simply can't match.

Tandem solar cells are emerging as the leading next-generation photovoltaic solution, with the technology positioned to help future satellites and space data centers run on ultra-lightweight solar power.

That framing points to the real application KIER is chasing. Spacecraft and satellites pay a steep cost — in launch weight and fuel — for every gram of power-generation hardware they carry. A thin-film tandem cell that trades a few percentage points of efficiency for a dramatic cut in weight and flexibility can out-compete heavier, rigid silicon arrays once you factor in launch economics.

Building on a decade of incremental records

This result didn't appear out of nowhere. KIER's own published track record includes the world's highest efficiency semi-transparent perovskite top cell at 21.68%, the first bifacial tandem solar cell developed in South Korea, and an earlier lightweight tandem cell record of 24.5% four-terminal efficiency. The 26.7% figure represents a roughly two-point jump over that prior mark — a meaningful gain in a field where records typically move in fractions of a percent.

Part of the improvement reportedly came from a nickel oxide-based catalytic process the KIER team developed to remove lithium ions from the hole transport layer, a materials-chemistry fix aimed at the kind of stability and efficiency losses that have historically limited perovskite-based devices.

Perovskite-based solar technology still faces real hurdles before it reaches mass production, particularly around long-term durability outside a lab environment. But each certified record — this one included — narrows the gap between "promising research material" and "material an engineer can actually spec into a satellite or rooftop array." For a technology that didn't exist in a usable form fifteen years ago, 26.7% on a lightweight, flexible stack is a marker of how fast the chemistry has matured.