Solar panels keep getting cheaper and more common, but even great hardware still leaves a lot of sunlight unused.
What if a cell could squeeze more charge out of the same photons, the tiny packets of light hitting your roof? On March 25, 2026, researchers from Kyushu University in Japan and Johannes Gutenberg University Mainz in Germany reported a lab result that pulls more energy carriers out of light than the number of photons absorbed.
Their setup reached about 130% quantum yield, meaning roughly one point three usable excited states were captured for every photon taken in. Associate Professor Yoichi Sasaki said, “We therefore needed an energy acceptor that selectively captures the multiplied triplet excitons after fission,” describing the bottleneck that has slowed this field for years.
The collaboration began when exchange student Adrian Sauer brought in materials long studied in his home lab, a reminder that science can move forward through unexpected connections.
Why solar cells hit a ceiling
A classic solar cell is built around a single junction inside a semiconductor, which is the part that separates charges so electricity can flow. In 1961, William Shockley and Hans Queisser laid out a theoretical ceiling for that kind of design, showing how fundamental losses keep an ideal single junction from turning all sunlight into power.
Under their assumptions, the best possible efficiency worked out to about 30%, even before you add real-world imperfections.
The reason is simple once you picture sunlight as a mix of energy packets. Low-energy infrared photons usually cannot push an electron into motion, while higher-energy photons shed their extra energy as heat after the useful part is taken. That waste helps explain why a roof needs a lot of panel area to make a serious dent in an electric bill.
The trick called singlet fission
When light lands on certain materials, it can create an exciton, a temporary bundle of energy shared by an electron and the “hole” it leaves behind. In singlet fission, one high-energy exciton splits into two lower-energy triplet excitons, which can potentially become two charge carriers. If both carriers are collected, one photon can do more than one unit of electrical work.
This idea is not brand new, and earlier devices have already hinted at what is possible. A 2013 report showed external quantum efficiency above 100%, meaning the device produced more than one charge carrier for some photons that hit it, and later work paired singlet fission layers with silicon in tandem setups that also crossed 100% at specific colors of light.
The hard part is that triplet excitons can be slippery. They often do not emit light easily, and they can vanish before a device can guide their energy into an electrical circuit.
What kept it from working
In many experiments, the energy takes a shortcut that ruins the payoff. Instead of splitting cleanly and being harvested, excitation can hop between molecules in a competing pathway, cutting multiplication short.
Chemists call this shortcut Förster resonance energy transfer, or FRET, which is a non-radiative handoff of excitation between nearby molecules. It can happen without emitting light, so it quietly drains energy away from the process you actually want.
A molybdenum “spin-flip” catcher
The new work centers on a metal complex, a molecule built around a metal atom that can be tuned like a custom tool. In this case, molybdenum helps create a “spin-flip” emitter that can absorb and emit near-infrared light, the kind just beyond red that our eyes cannot see, after an electron flips a quantum property called spin.
In plain language, it is designed to accept energy stored in triplet states that other materials struggle to use.
By matching energy levels across the system, the researchers steered energy toward triplet capture instead of the unwanted handoff that steals it. That tuning is what let the multiplied excitons move into a usable excited state, rather than fading away as wasted heat.
The tests were done with tetracene-based materials dissolved in a liquid, which makes it easier to mix molecules and watch energy move between them. It is a controlled environment, more like a chemistry beaker than a rooftop panel.
What 130%really means
A number above 100% can sound like a free lunch. It is not, and the key is that quantum yield counts events, not total watts. Here, about 130% quantum yield means the system ended up exciting about one point three of the molybdenum complexes per photon absorbed.
Energy is still conserved because one higher-energy photon can be converted into two lower-energy excitations, so you are splitting one packet into two. Think of it like breaking a bigger bill into two smaller ones. The theoretical ceiling for this style of multiplication can reach 200%, but real devices will be limited by imperfect transfer and material losses.
From beaker to rooftop
The result is still early-stage, and the team describes it as a proof of concept rather than a finished solar cell. Right now the measurements come from solution experiments, and the next step is solid-state versions where the materials sit together in stable layers. That shift matters because real devices must survive years of sun, heat, and weather without falling apart.
For now, no one should expect 130% efficient panels at the store. But the work is a reminder that solar progress is not only about better manufacturing – it is also about rewriting how light energy is handled. If that eventually translates to more watts per square foot, your electric bill could feel it.
The main study has been published in the Journal of the American Chemical Society.
