Every second, the Sun emits a colossal amount of energy to Earth; however, modern solar panels can capture only about one-third of this flow. For a long time, it was believed that this "physical ceiling" could not be overcome. But a team of scientists from Japan and Germany has developed an innovative method that allows them to bypass the Shockley-Queisser limit, which defines the maximum efficiency of solar cells. In their experiments, they managed to achieve a quantum yield of around 130%.
The research conducted by scientists from Kyushu University and Johannes Gutenberg University in Mainz is based on the principle of singlet fission. This process allows one high-energy photon to create two excitons (energy carriers) instead of one. However, there was a significant problem previously: parasitic energy transfer, which "absorbed" part of the energy before fission occurred.
The research team found a solution by applying a molybdenum complex—a "spin-flip" emitter that chooses the moment to capture energy only after triplet excitons are formed. In this system, an electron changes its spin under the influence of near-infrared light, allowing for more efficient energy absorption at the right stage, as reported by Scitech Daily.
As a result of the experiment with tetracene materials, the system achieved a quantum yield of 130%, surpassing the previous limit of 100%. This means that for every absorbed photon, about 1.3 molybdenum complexes were activated, allowing for the creation of more energy carriers than the number of incoming photons. Modern solar cells utilize only one-third of the energy from sunlight: low-energy photons cannot excite electrons, and the excess energy from high-energy photons is lost as heat. The singlet fission method helps to harness this excess energy, which could potentially significantly increase the efficiency of solar panels.
Currently, the research is at the concept validation stage. The next step is to integrate new materials into solid-state systems to create practical photovoltaic devices. The results could be beneficial not only in solar energy but also in LEDs and quantum technologies that utilize spin state control.
The record "The Limit of Solar Energy Conversion Has Been Overcome" first appeared in K-News.
