Mankind has been using solar energy for millennia. In the 7th century B.C., people used sunlight to ignite fires by reflecting the sun’s rays. Later, ancient civilizations like the Greeks and Romans used solar power for religious ceremonies and embodied static solar designs in their architecture. In the modern era, solar energy is used to power civilization, and one specific quantum photovoltaic dot seems to be the future, as it results in almost 200% more energy than traditional solar panels.
The new efficient quantum solar cell
Solar panel technology can be altered to achieve increased efficiencies by using heat and light, which is exactly what researchers, led by physics professor Chinedu Ekuma, at the laboratory of Lehigh University in Pennsylvania have been developing. Their scientific paper, Chemically tuned intermediate band states in atomically thin CuxGeSe/SnS quantum material for photovoltaic applications, was published in ScienceAdvance and declared that the new quantum material could be suitable for intermediate band solar cells (IBSCs).
The research team developed the proof of concept for a new thin-film photovoltaic cell absorber material that uses energy from reflected light and heat, as well as direct sunlight, which results in a level of 190% for external quantum efficiency (EQE) and an average photovoltaic absorption of 80%.
Note that quantum efficiency is not the same as conversion efficiency. EQE is the ratio of total electrons absorbed by the photovoltaic cell to the total number of photons that hit it. EQE essentially describes how effectively a photovoltaic cell converts photons into an electrical current.
“In traditional solar cells, the maximum EQE is 100%, representing the generation and collection of one electron for each photon absorbed from sunlight.” – Professor Ekuma.
This is what makes the new technology more efficient
These thin cells could potentially exceed the Shockley-Queisser limit – the maximum theoretical efficiency that a photovoltaic cell with a single p-n junction can reach. The calculation is done by examining the total electrical energy that is extracted per incident photon.
“The material’s efficiency leap is attributable largely to its distinctive ‘intermediate band states,’ specific energy levels that are positioned within the material’s electronic structure in a way that makes them ideal for solar energy conversion.These states have energy levels within the optimal subband gaps—energy ranges where the material can efficiently absorb sunlight and produce charge carriers.” – The research team.
The newly developed material is a two-dimensional Van der Waals (vdW) material, and it features a crystalline planar configuration ionically bonded. The heterostructure merges germanium (Ge), selenium (Se), and tin sulfide (SnS) with atoms of zerovalent copper (Cu) inserted between the material’s layers. The CuxGeSe/SnS material has an intermediate energy bandgap ranging from 0.78 eV and 1.26 eV. The team used this to design and prototype a thin-film solar cell with the proposed material as the active layer.
The quantum solar cell has the potential for this much efficiency
The team created a simulation that indicated that the cell EQE could range from 110% to 190%. By quantifying the absorber’s thickness, the cell optical production increased in wavelengths spanning from 600 to 1200 nm. The team concluded that the quick response and improved efficiency in Cu-intercalated samples demonstrably prove the potential of Cu-intercalated GeSe/SnS as a quantum material for utilization in advanced photovoltaic applications.
The team will be researching a practical way to place the newly created material in real solar cells in the future, while noting that the experimental methods used to create these materials are already “highly advanced.”
It may not be too long before these almost 200% efficient solar cells potentially send fossil fuels packing for good. The research may still be in the early stage of proof-of-concept, but other photovoltaic cells shooting past the 100% mark are currently developing, so nothing is impossible.