QAZAQ GREEN.  Scientists at Kyushu University, in collaboration with Johannes Gutenberg University Mainz, have developed a technology that allows solar cells to extract more energy than previously thought physically possible. The system achieved a quantum yield of 130%, surpassing the conventional 100% barrier.

Solar cells have long been constrained by the Shockley–Queisser limit, a physical ceiling that restricts energy conversion efficiency to roughly one-third of incoming sunlight. Lower-energy infrared photons cannot excite electrons, while higher-energy photons lose their excess as heat.

The researchers harnessed a process called singlet fission, in which one high-energy photon splits into two lower-energy excitons, theoretically doubling the energy output. The key challenge was capturing these excitons before their energy dissipated through an unwanted process known as Förster resonance energy transfer.

The solution came in the form of a molybdenum-based metal complex — a so-called spin-flip emitter — in which an electron flips its spin during absorption or emission of near-infrared light. This allows the complex to selectively capture the triplet excitons produced in singlet fission. By carefully tuning the energy levels, the team suppressed the wasteful transfer process and achieved a quantum yield of around 130%.

The work remains at the proof-of-concept stage, with experiments conducted in solution. The next step is to bring the materials together in the solid state for integration into working solar cells. Beyond photovoltaics, the technology holds potential for LEDs and next-generation quantum technologies.

The findings were published in the Journal of the American Chemical Society.