EPFL and CSEM Break 30% Efficiency Barrier With Perovskite-Silicon Triple-Junction Solar Cell

Overview

Researchers at EPFL’s Photovoltaics and Thin-Film Electronics Laboratory and CSEM, the Swiss Center for Electronics and Microtechnology, have achieved an independently certified efficiency of 30.02% for a perovskite-silicon triple-junction solar cell — the highest ever recorded for this class of device. The work, published in Nature on March 17, 2026, surpasses the previous certified record of 27.1% and marks a significant step toward closing the cost gap with expensive space-grade photovoltaics.

What We Know

• The triple-junction device combines a silicon bottom cell with two thin-film perovskite cells — a middle and a top cell — stacked on a single 54 cm² substrate, according to EPFL.
• The team addressed two fundamental bottlenecks simultaneously: insufficient voltage in the top cell and limited photocurrent in the middle cell, as described in the Nature paper.
• For the top cell, a non-volatile additive called 4-hydroxybenzylamine was used to guide perovskite crystal formation, suppress defects, and achieve open-circuit voltages of up to 1.405 V — a key figure for converting sunlight to electricity efficiently, according to EPFL.
• A three-step deposition strategy improved near-infrared absorption in the middle perovskite cell, which carries a large share of the solar spectrum, according to Interesting Engineering.
• Silicon oxide nanoparticles embedded between the silicon and middle perovskite cells act as a middle reflector, redirecting longer-wavelength photons back into the middle absorber to increase current, according to EurekAlert.
• The device was independently certified at 30.02% efficiency, compared with the prior record of 27.1% for triple-junction solar cells, as reported by Interesting Engineering.

What We Don’t Know

• The long-term stability and outdoor durability of the 54 cm² device have not yet been reported; the team has indicated that large-scale manufacturing and durability testing are next on the research roadmap.
• It is still unclear at what cost per watt the architecture can be manufactured at industrial scale, though the use of silicon and perovskite materials is considered far less expensive than the III-V semiconductors currently used in space-grade cells.

Context

Triple-junction solar cells use three light-absorbing layers tuned to different parts of the solar spectrum, allowing a single device to convert a wider range of photon energies than single-junction or tandem cells. Until recently, cells reaching this efficiency tier required expensive III-V compound semiconductors — materials estimated to cost around 1,000 times more per watt than conventional silicon cells — and were confined largely to satellites and concentrated-solar applications.

The EPFL and CSEM architecture replaces the two upper III-V junctions with perovskite thin films, which can be deposited at lower temperatures using scalable processes. According to EPFL, the team’s first triple-junction demonstration in 2018 reached only 13% efficiency; the jump to 30.02% over eight years illustrates the pace of improvement in perovskite technology.

Lead author Kerem Artuk described the significance of the result as showing that “with clever design and processing, we can approach performance levels traditionally reserved for the most expensive III–V multi-junction solar cells used in space,” according to EPFL. Lab head Christophe Ballif noted that the theoretical efficiency ceiling for triple-junction configurations is “well above 40%,” suggesting further room for improvement beyond today’s record.

For grid-scale and rooftop solar, higher efficiency translates directly into fewer panels needed to produce the same power output — a factor that matters for installations where land area or rooftop space is limited. Whether the current laboratory record can be replicated in manufacturable, durable products remains the central challenge for the research team and for the broader perovskite photovoltaic industry.