Quantum material reaches an efficiency of up to 190% in solar cells
Researchers at Lehigh University have developed a material that significantly improves the efficiency of solar panels.
A prototype incorporating this material as the active layer in a solar cell exhibits an average photovoltaic absorption rate of 80%, a high rate of photoexcited carrier generation, and an external quantum efficiency (EQE) that can reach 190%. This figure exceeds the theoretical Shockley-Queisser efficiency limit for silicon-based materials, advancing the field of quantum materials for solar photovoltaics.
This work represents a major advance in sustainable energy solutions, said Chinedu Ekuma, professor of physics at Lehigh. He and Lehigh doctoral candidate Srihari Kastuar recently published their findings in the journal Science Advances. Ekuma highlighted the innovative approaches that could soon redefine solar energy efficiency and accessibility.
The material’s significant efficiency improvement is largely due to its unique intermediate band states, which are energy levels within the material’s electronic structure that are ideally positioned for solar energy conversion.
These states have energy levels in the optimal subband gaps – energy ranges that can efficiently absorb sunlight and produce charge carriers – between 0.78 and 1.26 electron volts.
Additionally, the material excels at absorbing high levels in the infrared and visible regions of the electromagnetic spectrum.
In traditional solar cells, the maximum EQE is 100%, which corresponds to generating and collecting one electron for each photon absorbed. However, newer materials and configurations can generate and collect more than one electron per high-energy photon, achieving an EQE of more than 100%.
Multiple Exciton Generation (MEG) materials, although not yet widely commercialized, show enormous potential for improving the efficiency of solar energy systems. The material developed by Lehigh uses intermediate band states to capture photon energy that is typically lost in traditional cells, including energy lost through reflection and heat production.
The research team created this new material using van der Waals gaps, atomically small spaces between layered two-dimensional materials, to trap molecules or ions. Specifically, they placed zero-valent copper atoms between layers of germanium selenide (GeSe) and tin sulfide (SnS).
Ekuma developed the prototype based on extensive computer models that indicated the theoretical potential of the system. The fast response and improved efficiency strongly indicate the potential of Cu-intercalated GeSe/SnS as a quantum material for advanced photovoltaic applications, providing a path for efficiency improvements in solar energy conversion, he said.
While integrating this quantum material into existing solar energy systems requires further research, the techniques used to create these materials are already highly advanced, with scientists mastering precise methods for introducing atoms, ions and molecules.
Research report:Chemically tuned intermediate band states in atomically thin CuxGeSe/SnS quantum material for photovoltaic applications