Researchers at EPFL Switzerland achieved 34.6% power conversion efficiency in January 2026 using a perovskite-silicon tandem solar cell, surpassing the previous 33.9% record set by LONGi in 2024. This marks the highest verified efficiency for any solar cell technology approaching the theoretical Shockley-Queisser limit of 43% for tandem configurations.

What Technical Innovation Enabled the 34.6% Efficiency?

The EPFL team employed a cesium-formamidinium mixed-cation perovskite top cell with improved bandgap alignment at 1.68 eV, paired with a crystalline silicon bottom cell. The key advancement involved a self-assembled monolayer hole-transport material that reduced interface recombination losses by 18% compared to conventional PTAA layers. This interface optimization, combined with anti-reflective nanostructured coatings, captured previously wasted photons in the near-infrared spectrum.

How Does This Compare to Commercial Silicon Panels?

Standard monocrystalline silicon panels achieve 22-24% efficiency in production, while the best laboratory silicon cells reach 26.7%. This tandem approach effectively adds 8-10 percentage points by stacking a perovskite layer that absorbs high-energy photons while allowing lower-energy light through to silicon. Oxford PV currently manufactures perovskite-silicon tandems at 28% efficiency commercially, suggesting this 34.6% lab result could translate to 30%+ production modules by 2028.