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The new material consists of a heterostructure that combines germanium, selenium and tin sulfide, which also integrates zero-valent copper atoms. It has an average photovoltaic absorption of more than 80% and could help photovoltaic cells break the Shockley-Queisser efficiency limit, according to its creators.
Researchers at Lehigh University in the United States have developed a new absorbent material for thin-film solar cells that reportedly exhibits an average photovoltaic absorption of 80% and external quantum efficiency (EQE). of 190%.
The EQE is the relationship between the number of electrons collected by the solar cell and the number of photons that reach it. Defines how well a solar cell converts photons into electrical current. “In traditional solar cells, the maximum EQE is 100%, which represents the generation and collection of one electron for each photon absorbed from sunlight,” explains Chinedu Ekuma, lead author of the research, in a statement.
In the article “ Chemically tuned intermediate band states in atomically thin CuxGeSe/SnS quantum material for photovoltaic applications ,” published in ScienceAdvance , the researchers explain that the New quantum material may be ideal for intermediate band solar cells (IBSC).
These devices are believed to have the potential to exceed the Shockley-Queisser limit, that is, the maximum theoretical efficiency that a solar cell with a single p-n junction can achieve. It is calculated by examining the amount of electrical energy that is extracted per incident photon.
The materials jump in efficiency is largely attributed to its characteristic "intermediate band states," specific energy levels that are situated within the materials electronic structure in a way that makes them ideal for solar energy conversion. , explain the scientists. “These states have energy levels within the optimal subband ranges, energy ranges in which the material can effectively absorb sunlight and produce charge carriers.”
The new material is a 2D two-dimensional Van der Waals (vdW), which means it has a planar crystalline configuration held together by ionic bonds. It consists of a heterostructure that combines germanium (Ge), selenium (Se) and tin sulfide (Sns) with zero-valent copper (Cu) atoms inserted between the layers of the material.
The CuxGeSe/SnS material presents an intermediate energy bandgap ranging between 0.78 eV and 1.26 eV. With it, the group designed and modeled a thin film solar cell with the proposed material as the active layer.
The device was assumed to be based on an indium tin oxide (ITO) substrate, a zinc oxide (ZnO)-based electron transport layer (ETL), a CuxGeSe/SnS absorber, and a gold metal contact ( Au). “In our design, the atomically thin GeSe and SnS are stacked vertically, which facilitates the easy integration of the hybrid structures through van der Waals interactions,” the research team specified.
The simulation showed that the EQE of the cell can range from 110% to 190%. The researchers also verified that, by increasing the thickness of the absorber, the optical activity of the cell increases at wavelengths ranging from 600 to 1,200 nm.
“The rapid response and increased efficiency of the Cu-intercalated samples clearly indicate the potential of Cu-intercalated GeSe/SnS as a quantum material for use in advanced photovoltaic applications, offering a pathway to improve photovoltaic conversion efficiency.” solar energy”, they concluded.
Looking ahead, the research group noted that further research is needed to find a practical way to integrate the new material into real solar cells. However, they also noted that the experimental techniques used to create these materials are already “very advanced.” |
