A method has been found to overcome the fundamental efficiency limit of solar panels.

New method turns “excess” light energy into extra charge carriers, beating the classic limit

Researchers have set out a route to sidestep one of the central, long-standing constraints in solar power: the Shockley–Queisser limit. This is the maximum theoretical efficiency of a solar cell, regarded for more than 60 years as the upper ceiling for photovoltaic performance.

Modern solar panels rely on photovoltaic cells-semiconductors that convert sunlight into electricity. Yet even under ideal conditions, they can only harvest a portion of the Sun’s energy. The theoretical cap is 33%, while commercial panels typically reach only about 25%.

The reason lies in both the nature of light and thermodynamics. Sunlight spans a broad range of energies, but a solar cell can convert only a relatively narrow band efficiently. Photons that do not carry enough energy pass through the material, while higher-energy photons shed their surplus energy as heat.

Singlet fission and the Shockley–Queisser limit: using high-energy blue light that was previously “lost”

In a new study, teams from Japan and Germany described how to make use of a part of the spectrum that has usually been treated as “wasted”-namely high-energy blue light, which under normal circumstances cannot be converted into electricity efficiently.

They demonstrated that when this light shines on a specially designed compound, the energy of a single photon can effectively be “split” into two useful excitations. In doing so, they achieved an efficiency of around 130%-meaning that for every 100 absorbed photons, the system generated 130 energy carriers.

At the heart of the approach is singlet fission. This phenomenon allows one excited state to produce two, increasing the number of charge carriers without increasing the number of absorbed photons.

To implement the method, the researchers combined the organic molecule tetracene with the metallic element molybdenum. Tetracene has previously been used for handling high-energy light, but such systems have faced issues with stability and long-term operation. According to the authors, introducing molybdenum overcame those limitations.

One of the study’s authors, chemist Yoichi Sasaki of Kyushu University, explained that there are two main strategies for moving beyond the Shockley–Queisser limit. The first is to convert low-energy infrared photons into higher-energy photons. The second is to use singlet fission to obtain two excitations from one photon-an approach realised in this work.

For now, the research remains at the laboratory stage. The results show that bypassing a fundamental constraint is possible in principle, but practical deployment in commercial solar panels is still a long way off.

Even so, the work represents one of the most striking steps towards revisiting a limit long considered unbeatable. If the technology can be scaled up, it could reshape how photovoltaic cells are designed and raise the efficiency of solar power without radically changing its underlying architecture.